Last updated on December 2nd, 2023 at 04:09 pm
Title 40—Protection of Environment–Volume 2
CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
SUBCHAPTER C—AIR PROGRAMS
PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS
§ 50.1 Definitions.
(a) As used in this part, all terms not defined herein shall have the meaning given them by the Act.
(b) Act means the Clean Air Act, as amended (42 U.S.C. 1857–18571, as amended by Pub. L. 91–604).
(c) Agency means the Environmental Protection Agency.
(d) Administrator means the Administrator of the Environmental Protection Agency.
(e) Ambient air means that portion of the atmosphere, external to buildings, to which the general public has access.
(f) Reference method means a method of sampling and analyzing the ambient air for an air pollutant that is specified as a reference method in an appendix to this part, or a method that has been designated as a reference method in accordance with part 53 of this chapter; it does not include a method for which a reference method designation has been cancelled in accordance with § 53.11 or § 53.16 of this chapter.
(g) Equivalent method means a method of sampling and analyzing the ambient air for an air pollutant that has been designated as an equivalent method in accordance with part 53 of this chapter; it does not include a method for which an equivalent method designation has been cancelled in accordance with § 53.11 or § 53.16 of this chapter.
(h) Traceable means that a local standard has been compared and certified either directly or via not more than one intermediate standard, to a primary standard such as a National Bureau of Standards Standard Reference Material (NBS SRM), or a USEPA/NBS-approved Certified Reference Material (CRM).
(i) Indian country is as defined in 18 U.S.C. 1151.
(j) Exceptional event means an event(s) and its resulting emissions that affect air quality in such a way that there exists a clear causal relationship between the specific event(s) and the monitored exceedance(s) or violation(s), is not reasonably controllable or preventable, is an event(s) caused by human activity that is unlikely to recur at a particular location or a natural event(s), and is determined by the Administrator in accordance with 40 CFR 50.14 to be an exceptional event. It does not include air pollution relating to source noncompliance. Stagnation of air masses and meteorological inversions do not directly cause pollutant emissions and are not exceptional events. Meteorological events involving high temperatures or lack of precipitation (i.e., severe, extreme or exceptional drought) also do not directly cause pollutant emissions and are not considered exceptional events. However, conditions involving high temperatures or lack of precipitation may promote occurrences of particular types of exceptional events, such as wildfires or high wind events, which do directly cause emissions.
(k) Natural event means an event and its resulting emissions, which may recur at the same location, in which human activity plays little or no direct causal role. For purposes of the definition of a natural event, anthropogenic sources that are reasonably controlled shall be considered to not play a direct role in causing emissions.
(l) Exceedance with respect to a national ambient air quality standard means one occurrence of a measured or modeled concentration that exceeds the specified concentration level of such standard for the averaging period specified by the standard.
(m) Prescribed fire is any fire intentionally ignited by management actions in accordance with applicable laws, policies, and regulations to meet specific land or resource management objectives.
(n) Wildfire is any fire started by an unplanned ignition caused by lightning; volcanoes; other acts of nature; unauthorized activity; or accidental, human-caused actions, or a prescribed fire that has developed into a wildfire. A wildfire that predominantly occurs on wildland is a natural event.
(o) Wildland means an area in which human activity and development are essentially non-existent, except for roads, railroads, power lines, and similar transportation facilities. Structures, if any, are widely scattered.
(p) High wind dust event is an event that includes the high-speed wind and the dust that the wind entrains and transports to a monitoring site.
(q) High wind threshold is the minimum wind speed capable of causing particulate matter emissions from natural undisturbed lands in the area affected by a high wind dust event.
(r) Federal land manager means, consistent with the definition in 40 CFR 51.301, the Secretary of the department with authority over the Federal Class I area (or the Secretary’s designee) or, with respect to Roosevelt-Campobello International Park, the Chairman of the Roosevelt-Campobello International Park Commission.
§ 50.2 Scope.
(a) National primary and secondary ambient air quality standards under section 109 of the Act are set forth in this part.
(b) National primary ambient air quality standards define levels of air quality which the Administrator judges are necessary, with an adequate margin of safety, to protect the public health. National secondary ambient air quality standards define levels of air quality which the Administrator judges necessary to protect the public welfare from any known or anticipated adverse effects of a pollutant. Such standards are subject to revision, and additional primary and secondary standards may be promulgated as the Administrator deems necessary to protect the public health and welfare.
(c) The promulgation of national primary and secondary ambient air quality standards shall not be considered in any manner to allow significant deterioration of existing air quality in any portion of any State or Indian country.
(d) The proposal, promulgation, or revision of national primary and secondary ambient air quality standards shall not prohibit any State or Indian country from establishing ambient air quality standards for that State or area under a tribal CAA program or any portion thereof which are more stringent than the national standards.
§ 50.3 Reference conditions.
All measurements of air quality that are expressed as mass per unit volume (e.g., micrograms per cubic meter) other than for particulate matter (PM
§ 50.4 National primary ambient air quality standards for sulfur oxides (sulfur dioxide).
(a) The level of the annual standard is 0.030 parts per million (ppm), not to be exceeded in a calendar year. The annual arithmetic mean shall be rounded to three decimal places (fractional parts equal to or greater than 0.0005 ppm shall be rounded up).
(b) The level of the 24-hour standard is 0.14 parts per million (ppm), not to be exceeded more than once per calendar year. The 24-hour averages shall be determined from successive nonoverlapping 24-hour blocks starting at midnight each calendar day and shall be rounded to two decimal places (fractional parts equal to or greater than 0.005 ppm shall be rounded up).
(c) Sulfur oxides shall be measured in the ambient air as sulfur dioxide by the reference method described in appendix A to this part or by an equivalent method designated in accordance with part 53 of this chapter.
(d) To demonstrate attainment, the annual arithmetic mean and the second-highest 24-hour averages must be based upon hourly data that are at least 75 percent complete in each calendar quarter. A 24-hour block average shall be considered valid if at least 75 percent of the hourly averages for the 24-hour period are available. In the event that only 18, 19, 20, 21, 22, or 23 hourly averages are available, the 24-hour block average shall be computed as the sum of the available hourly averages using 18, 19, etc. as the divisor. If fewer than 18 hourly averages are available, but the 24-hour average would exceed the level of the standard when zeros are substituted for the missing values, subject to the rounding rule of paragraph (b) of this section, then this shall be considered a valid 24-hour average. In this case, the 24-hour block average shall be computed as the sum of the available hourly averages divided by 24.
(e) The standards set forth in this section will remain applicable to all areas notwithstanding the promulgation of SO
§ 50.5 National secondary ambient air quality standard for sulfur oxides (sulfur dioxide).
(a) The level of the 3-hour standard is 0.5 parts per million (ppm), not to be exceeded more than once per calendar year. The 3-hour averages shall be determined from successive nonoverlapping 3-hour blocks starting at midnight each calendar day and shall be rounded to 1 decimal place (fractional parts equal to or greater than 0.05 ppm shall be rounded up).
(b) Sulfur oxides shall be measured in the ambient air as sulfur dioxide by the reference method described in appendix A of this part or by an equivalent method designated in accordance with part 53 of this chapter.
(c) To demonstrate attainment, the second-highest 3-hour average must be based upon hourly data that are at least 75 percent complete in each calendar quarter. A 3-hour block average shall be considered valid only if all three hourly averages for the 3-hour period are available. If only one or two hourly averages are available, but the 3-hour average would exceed the level of the standard when zeros are substituted for the missing values, subject to the rounding rule of paragraph (a) of this section, then this shall be considered a valid 3-hour average. In all cases, the 3-hour block average shall be computed as the sum of the hourly averages divided by 3.
§ 50.6 National primary and secondary ambient air quality standards for PM10 .
(a) The level of the national primary and secondary 24-hour ambient air quality standards for particulate matter is 150 micrograms per cubic meter (µg/m
(b) [Reserved]
(c) For the purpose of determining attainment of the primary and secondary standards, particulate matter shall be measured in the ambient air as PM
(1) A reference method based on appendix J and designated in accordance with part 53 of this chapter, or
(2) An equivalent method designated in accordance with part 53 of this chapter.
§ 50.7 National primary and secondary ambient air quality standards for PM2.5 .
(a) The national primary and secondary ambient air quality standards for particulate matter are 15.0 micrograms per cubic meter (µg/m
(1) A reference method based on appendix L of this part and designated in accordance with part 53 of this chapter; or
(2) An equivalent method designated in accordance with part 53 of this chapter.
(b) The annual primary and secondary PM
(c) The 24-hour primary and secondary PM
§ 50.8 National primary ambient air quality standards for carbon monoxide.
(a) The national primary ambient air quality standards for carbon monoxide are:
(1) 9 parts per million (10 milligrams per cubic meter) for an 8-hour average concentration not to be exceeded more than once per year and
(2) 35 parts per million (40 milligrams per cubic meter) for a 1-hour average concentration not to be exceeded more than once per year.
(b) The levels of carbon monoxide in the ambient air shall be measured by:
(1) A reference method based on appendix C and designated in accordance with part 53 of this chapter, or
(2) An equivalent method designated in accordance with part 53 of this chapter.
(c) An 8-hour average shall be considered valid if at least 75 percent of the hourly average for the 8-hour period are available. In the event that only six (or seven) hourly averages are available, the 8-hour average shall be computed on the basis of the hours available using six (or seven) as the divisor.
(d) When summarizing data for comparision with the standards, averages shall be stated to one decimal place. Comparison of the data with the levels of the standards in parts per million shall be made in terms of integers with fractional parts of 0.5 or greater rounding up.
§ 50.9 National 1-hour primary and secondary ambient air quality standards for ozone.
(a) The level of the national 1-hour primary and secondary ambient air quality standards for ozone measured by a reference method based on appendix D to this part and designated in accordance with part 53 of this chapter, is 0.12 parts per million (235 µg/m
(b) The 1-hour standards set forth in this section will remain applicable to all areas notwithstanding the promulgation of 8-hour ozone standards under § 50.10. The 1-hour NAAQS set forth in paragraph (a) of this section will no longer apply to an area one year after the effective date of the designation of that area for the 8-hour ozone NAAQS pursuant to section 107 of the Clean Air Act. Area designations and classifications with respect to the 1-hour standards are codified in 40 CFR part 81.
§ 50.10 National 8-hour primary and secondary ambient air quality standards for ozone.
(a) The level of the national 8-hour primary and secondary ambient air quality standards for ozone, measured by a reference method based on appendix D to this part and designated in accordance with part 53 of this chapter, is 0.08 parts per million (ppm), daily maximum 8-hour average.
(b) The 8-hour primary and secondary ozone ambient air quality standards are met at an ambient air quality monitoring site when the average of the annual fourth-highest daily maximum 8-hour average ozone concentration is less than or equal to 0.08 ppm, as determined in accordance with appendix I to this part.
(c) Until the effective date of the final Implementation of the 2008 National Ambient Air Quality Standards for Ozone: State Implementation Plan Requirements Rule (final SIP Requirements Rule) to be codified at 40 CFR 51.1100 et seq., the 1997 ozone NAAQS set forth in this section will continue in effect, notwithstanding the promulgation of the 2008 ozone NAAQS under § 50.15. The 1997 ozone NAAQS set forth in this section will no longer apply upon the effective date of the final SIP Requirements Rule. For purposes of the anti-backsliding requirements of § 51.1105, § 51.165 and Appendix S to part 51, the area designations and classifications with respect to the revoked 1997 ozone NAAQS are codified in 40 CFR part 81.
§ 50.11 National primary and secondary ambient air quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator).
(a) The level of the national primary annual ambient air quality standard for oxides of nitrogen is 53 parts per billion (ppb, which is 1 part in 1,000,000,000), annual average concentration, measured in the ambient air as nitrogen dioxide.
(b) The level of the national primary 1-hour ambient air quality standard for oxides of nitrogen is 100 ppb, 1-hour average concentration, measured in the ambient air as nitrogen dioxide.
(c) The level of the national secondary ambient air quality standard for nitrogen dioxide is 0.053 parts per million (100 micrograms per cubic meter), annual arithmetic mean concentration.
(d) The levels of the standards shall be measured by:
(1) A reference method based on appendix F to this part; or
(2) By a Federal equivalent method (FEM) designated in accordance with part 53 of this chapter.
(e) The annual primary standard is met when the annual average concentration in a calendar year is less than or equal to 53 ppb, as determined in accordance with appendix S of this part for the annual standard.
(f) The 1-hour primary standard is met when the three-year average of the annual 98th percentile of the daily maximum 1-hour average concentration is less than or equal to 100 ppb, as determined in accordance with appendix S of this part for the 1-hour standard.
(g) The secondary standard is attained when the annual arithmetic mean concentration in a calendar year is less than or equal to 0.053 ppm, rounded to three decimal places (fractional parts equal to or greater than 0.0005 ppm must be rounded up). To demonstrate attainment, an annual mean must be based upon hourly data that are at least 75 percent complete or upon data derived from manual methods that are at least 75 percent complete for the scheduled sampling days in each calendar quarter.
§ 50.12 National primary and secondary ambient air quality standards for lead.
(a) National primary and secondary ambient air quality standards for lead and its compounds, measured as elemental lead by a reference method based on appendix G to this part, or by an equivalent method, are: 1.5 micrograms per cubic meter, maximum arithmetic mean averaged over a calendar quarter.
(b) The standards set forth in this section will remain applicable to all areas notwithstanding the promulgation of lead national ambient air quality standards (NAAQS) in § 50.16. The lead NAAQS set forth in this section will no longer apply to an area one year after the effective date of the designation of that area, pursuant to section 107 of the Clean Air Act, for the lead NAAQS set forth in § 50.16; except that for areas designated nonattainment for the lead NAAQS set forth in this section as of the effective date of § 50.16, the lead NAAQS set forth in this section will apply until that area submits, pursuant to section 191 of the Clean Air Act, and EPA approves, an implementation plan providing for attainment and/or maintenance of the lead NAAQS set forth in § 50.16.
§ 50.13 National primary and secondary ambient air quality standards for PM2.5 .
(a) The national primary and secondary ambient air quality standards for particulate matter are 15.0 micrograms per cubic meter (µg/m
(1) A reference method based on appendix L of this part and designated in accordance with part 53 of this chapter; or
(2) An equivalent method designated in accordance with part 53 of this chapter.
(b) The annual primary and secondary PM
(c) The 24-hour primary and secondary PM
(d) Until the effective date of the final Fine Particulate Matter National Ambient Air Quality Standards: State Implementation Plan Requirements rule to be codified at 40 CFR 51.1000 through 51.1016, the 1997 annual PM
§ 50.14 Treatment of air quality monitoring data influenced by exceptional events.
(a) Requirements—(1) Scope. (i) This section applies to the treatment of data showing exceedances or violations of any national ambient air quality standard for purposes of the following types of regulatory determinations by the Administrator:
(A) An action to designate an area, pursuant to Clean Air Act section 107(d)(1), or redesignate an area, pursuant to Clean Air Act section 107(d)(3), for a particular national ambient air quality standard;
(B) The assignment or re-assignment of a classification category to a nonattainment area where such classification is based on a comparison of pollutant design values, calculated according to the specific data handling procedures in 40 CFR part 50 for each national ambient air quality standard, to the level of the relevant national ambient air quality standard;
(C) A determination regarding whether a nonattainment area has attained the level of the appropriate national ambient air quality standard by its specified deadline;
(D) A determination that an area has data for the specific NAAQS, which qualify the area for an attainment date extension under the CAA provisions for the applicable pollutant;
(E) A determination under Clean Air Act section 110(k)(5), if based on an area violating a national ambient air quality standard, that the state implementation plan is inadequate under the requirements of Clean Air Act section 110; and
(F) Other actions on a case-by-case basis as determined by the Administrator.
(ii) A State, federal land manager or other federal agency may request the Administrator to exclude data showing exceedances or violations of any national ambient air quality standard that are directly due to an exceptional event from use in determinations identified in paragraph (a)(1)(i) of this section by demonstrating to the Administrator’s satisfaction that such event caused a specific air pollution concentration at a particular air quality monitoring location.
(A) For a federal land manager or other federal agency to be eligible to initiate such a request for data exclusion, the federal land manager or other federal agency must:
(1) Either operate a regulatory monitor that has been affected by an exceptional event or manage land on which an exceptional event occurred that influenced a monitored concentration at a regulatory monitor; and
(2) Initiate such a request only after the State in which the affected monitor is located concurs with the federal land manager’s or other federal agency’s submittal.
(B) With regard to such a request, all provisions in this section that are expressed as requirements applying to a State shall, except as noted, be requirements applying to the federal land manager or other federal agency.
(C) Provided all provisions in this section are met, the Administrator shall allow a State to submit demonstrations for any regulatory monitor within its jurisdictional bounds, including those operated by federal land managers, other federal agencies and delegated local agencies.
(D) Where multiple agencies within a state submit demonstrations for events that meet the requirements of the Exceptional Events Rule, a State submittal shall have primacy for any regulatory monitor within its jurisdictional bounds.
(2) A demonstration to justify data exclusion may include any reliable and accurate data, but must specifically address the elements in paragraphs (c)(3)(iv) and (v) of this section.
(b) Determinations by the Administrator—(1) Generally. The Administrator shall exclude data from use in determinations of exceedances and violations identified in paragraph (a)(1)(i) of this section where a State demonstrates to the Administrator’s satisfaction that an exceptional event caused a specific air pollution concentration at a particular air quality monitoring location and otherwise satisfies the requirements of this section.
(2) Fireworks displays. The Administrator shall exclude data from use in determinations of exceedances and violations where a State demonstrates to the Administrator’s satisfaction that emissions from fireworks displays caused a specific air pollution concentration in excess of one or more national ambient air quality standards at a particular air quality monitoring location and otherwise satisfies the requirements of this section. Such data will be treated in the same manner as exceptional events under this rule, provided a State demonstrates that such use of fireworks is significantly integral to traditional national, ethnic, or other cultural events including, but not limited to, July Fourth celebrations that satisfy the requirements of this section.
(3) Prescribed fires. (i) The Administrator shall exclude data from use in determinations of exceedances and violations, where a State demonstrates to the Administrator’s satisfaction that emissions from prescribed fires caused a specific air pollution concentration in excess of one or more national ambient air quality standards at a particular air quality monitoring location and otherwise satisfies the requirements of this section.
(ii) In addressing the requirements set forth in paragraph (c)(3)(iv)(D) of this section regarding the not reasonably controllable or preventable criterion:
(A) With respect to the requirement that a prescribed fire be not reasonably controllable, the State must either certify to the Administrator that it has adopted and is implementing a smoke management program or the State must demonstrate that the burn manager employed appropriate basic smoke management practices identified in Table 1 to § 50.14. Where a burn manager employs appropriate basic smoke management practices, the State may rely on a statement or other documentation provided by the burn manager that he or she employed those practices. If an exceedance or violation of a NAAQS occurs when a prescribed fire is employing an appropriate basic smoke management practices approach, the State and the burn manager must undertake a review of the subject fire, including a review of the basic smoke management practices applied during the subject fire to ensure the protection of air quality and public health and progress towards restoring and/or maintaining a sustainable and resilient wildland ecosystem. If the prescribed fire becomes the subject of an exceptional events demonstration, documentation of the post-burn review must accompany the demonstration.
(B) If the State anticipates satisfying the requirements of paragraph (c)(3)(iv)(D) of this section by employing the appropriate basic smoke management practices identified in Table 1 to § 50.14, then:
(1) The State, federal land managers, and other entities as appropriate, must periodically collaborate with burn managers operating within the jurisdiction of the State to discuss and document the process by which air agencies and land managers will work together to protect public health and manage air quality impacts during the conduct of prescribed fires on wildland. Such discussions must include outreach and education regarding general expectations for the selection and application of appropriate basic smoke management practices and goals for advancing strategies and increasing adoption and communication of the benefits of appropriate basic smoke management practices;
(2) The State, federal land managers and burn managers shall have an initial implementation period, defined as being 2 years from September 30, 2016, to implement the collaboration and outreach effort identified in paragraph (b)(3)(ii)(B)(1) of this section; and
(3) Except as provided in paragraph (b)(3)(ii)(B)(2) of this section, the Administrator shall not place a concurrence flag in the appropriate field for the data record in the AQS database, as specified in paragraph (c)(2)(ii) of this section, if the data are associated with a prescribed fire on wildland unless the requirements of paragraph (b)(3)(ii)(B)(1) of this section have been met and associated documentation accompanies any applicable exceptional events demonstration. The Administrator may nonconcur or defer action on such a demonstration.
(C) With respect to the requirement that a prescribed fire be not reasonably preventable, the State may rely upon and reference a multi-year land or resource management plan for a wildland area with a stated objective to establish, restore and/or maintain a sustainable and resilient wildland ecosystem and/or to preserve endangered or threatened species through a program of prescribed fire provided that the Administrator determines that there is no compelling evidence to the contrary in the record and the use of prescribed fire in the area has not exceeded the frequency indicated in that plan.
(iii) Provided the Administrator determines that there is no compelling evidence to the contrary in the record, in addressing the requirements set forth in paragraph (c)(3)(iv)(E) of this section regarding the human activity unlikely to recur at a particular location criterion for demonstrations involving prescribed fires on wildland, the State must describe the actual frequency with which a burn was conducted, but may rely upon and reference an assessment of the natural fire return interval or the prescribed fire frequency needed to establish, restore and/or maintain a sustainable and resilient wildland ecosystem contained in a multi-year land or resource management plan with a stated objective to establish, restore and/or maintain a sustainable and resilient wildland ecosystem and/or to preserve endangered or threatened species through a program of prescribed fire.
Table 1 to § 50.14—Summary of Basic Smoke Management Practices, Benefit Achieved With the BSMP, and When it is Applied
Basic Smoke Management Practice b | Benefit achieved with the BSMP | When the BSMP is applied—before/during/after the burn |
---|---|---|
Evaluate Smoke Dispersion Conditions | Minimize smoke impacts | Before, During, After. |
Monitor Effects on Air Quality | Be aware of where the smoke is going and degree it impacts air quality | Before, During, After. |
Record-Keeping/Maintain a Burn/Smoke Journal | Retain information about the weather, burn and smoke. If air quality problems occur, documentation helps analyze and address air regulatory issues. | Before, During, After. |
Communication—Public Notification | Notify neighbors and those potentially impacted by smoke, especially sensitive receptors | Before, During. |
Consider Emission Reduction Techniques | Reducing emissions through mechanisms such as reducing fuel loading can reduce downwind impacts | Before, During, After. |
Share the Airshed—Coordination of Area Burning | Coordinate multiple burns in the area to manage exposure of the public to smoke | Before, During, After. |
a The EPA believes that elements of these BSMP could also be practical and beneficial to apply to wildfires for areas likely to experience recurring wildfires.
b The listing of BSMP in this table is not intended to be all-inclusive. Not all BSMP are appropriate for all burns. Goals for applicability should retain flexibility to allow for onsite variation and site-specific conditions that can be variable on the day of the burn. Burn managers can consider other appropriate BSMP as they become available due to technological advancement or programmatic refinement.
(4) Wildfires. The Administrator shall exclude data from use in determinations of exceedances and violations where a State demonstrates to the Administrator’s satisfaction that emissions from wildfires caused a specific air pollution concentration in excess of one or more national ambient air quality standard at a particular air quality monitoring location and otherwise satisfies the requirements of this section. Provided the Administrator determines that there is no compelling evidence to the contrary in the record, the Administrator will determine every wildfire occurring predominantly on wildland to have met the requirements identified in paragraph (c)(3)(iv)(D) of this section regarding the not reasonably controllable or preventable criterion.
(5) High wind dust events. (i) The Administrator shall exclude data from use in determinations of exceedances and violations, where a State demonstrates to the Administrator’s satisfaction that emissions from a high wind dust event caused a specific air pollution concentration in excess of one or more national ambient air quality standards at a particular air quality monitoring location and otherwise satisfies the requirements of this section provided that such emissions are from high wind dust events.
(ii) The Administrator will consider high wind dust events to be natural events in cases where windblown dust is entirely from natural undisturbed lands in the area or where all anthropogenic sources are reasonably controlled as determined in accordance with paragraph (b)(8) of this section.
(iii) The Administrator will accept a high wind threshold of a sustained wind of 25 mph for areas in the States of Arizona, California, Colorado, Kansas, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, Utah, and Wyoming provided this value is not contradicted by evidence in the record at the time the State submits a demonstration. In lieu of this threshold, States can identify and use an Administrator-approved alternate area-specific high wind threshold that is more representative of local or regional conditions, if appropriate.
(iv) In addressing the requirements set forth in paragraph (c)(3)(iv)(D) of this section regarding the not reasonably preventable criterion, the State shall not be required to provide a case-specific justification for a high wind dust event.
(v) With respect to the not reasonably controllable criterion of paragraph (c)(3)(iv)(D) of this section, dust controls on an anthropogenic source shall be considered reasonable in any case in which the controls render the anthropogenic source as resistant to high winds as natural undisturbed lands in the area affected by the high wind dust event. The Administrator may determine lesser controls reasonable on a case-by-case basis.
(vi) For large-scale and high-energy high wind dust events, the Administrator will generally consider a demonstration documenting the nature and extent of the event to be sufficient with respect to the not reasonably controllable criterion of paragraph (c)(3)(iv)(D) of this section provided the State provides evidence showing that the event satisfies the following:
(A) The event is associated with a dust storm and is the focus of a Dust Storm Warning.
(B) The event has sustained winds that are greater than or equal to 40 miles per hour.
(C) The event has reduced visibility equal to or less than 0.5 miles.
(6) Stratospheric Intrusions. Where a State demonstrates to the Administrator’s satisfaction that emissions from stratospheric intrusions caused a specific air pollution concentration in excess of one or more national ambient air quality standard at a particular air quality monitoring location and otherwise satisfies the requirements of this section, the Administrator will determine stratospheric intrusions to have met the requirements identified in paragraph (c)(3)(iv)(D) of this section regarding the not reasonably controllable or preventable criterion and shall exclude data from use in determinations of exceedances and violations.
(7) Determinations with respect to event aggregation, multiple national ambient air quality standards for the same pollutant, and exclusion of 24-hour values for particulate matter.
(i) Where a State demonstrates to the Administrator’s satisfaction that for national ambient air quality standards with averaging or cumulative periods less than or equal to 24 hours the aggregate effect of events occurring on the same day has caused an exceedance or violation, the Administrator shall determine such collective data to satisfy the requirements in paragraph (c)(3)(iv)(B) of this section regarding the clear causal relationship criterion. Where a State demonstrates to the Administrator’s satisfaction that for national ambient air quality standards with averaging or cumulative periods longer than 24 hours the aggregate effect of events occurring on different days has caused an exceedance or violation, the Administrator shall determine such collective data to satisfy the requirements in paragraph (c)(3)(iv)(B) of this section regarding the clear causal relationship criterion.
(ii) The Administrator shall accept as part of a demonstration for the clear causal relationship in paragraph (c)(3)(iv)(B) of this section with respect to a 24-hour NAAQS, a State’s comparison of a 24-hour concentration of any national ambient air quality standard pollutant to the level of a national ambient air quality standard for the same pollutant with a longer averaging period. The Administrator shall also accept as part of a demonstration for the clear causal relationship in paragraph (c)(3)(iv)(B) of this section with respect to a NAAQS with a longer averaging period, a State’s comparison of a 24-hour concentration of any national ambient air quality standard pollutant to the level of the national ambient air quality standard for the same pollutant with a longer averaging period, without the State having to demonstrate that the event caused the annual average concentration of the pollutant to exceed the level of the NAAQS with the longer averaging period.
(iii) Where a State operates a continuous analyzer that has been designated as a Federal Equivalent Method monitor as defined in 40 CFR 50.1(g) that complies with the monitoring requirements of 40 CFR part 58, Appendix C, and the State believes that collected data have been influenced by an event, in following the process outlined in paragraph (c)(2) of this section, the State shall create an initial event description and flag the associated event-influenced data that have been submitted to the AQS database for the affected monitor. Where a State demonstrates to the Administrator’s satisfaction that such data satisfy the requirements in paragraph (c)(3)(iv)(B) of this section regarding the clear causal relationship criterion and otherwise satisfy the requirements of this section, the Administrator shall agree to exclude all data within the affected calendar day(s).
(8) Determinations with respect to the not reasonably controllable or preventable criterion. (i) The not reasonably controllable or preventable criterion has two prongs that the State must demonstrate: prevention and control.
(ii) The Administrator shall determine that an event is not reasonably preventable if the State shows that reasonable measures to prevent the event were applied at the time of the event.
(iii) The Administrator shall determine that an event is not reasonably controllable if the State shows that reasonable measures to control the impact of the event on air quality were applied at the time of the event.
(iv) The Administrator shall assess the reasonableness of available controls for anthropogenic sources based on information available as of the date of the event.
(v) Except where a State, tribal or federal air agency is obligated to revise its state implementation plan, tribal implementation plan, or federal implementation plan, the Administrator shall consider enforceable control measures implemented in accordance with a state implementation plan, tribal implementation plan, or federal implementation plan, approved by the EPA within 5 years of the date of the event, that address the event-related pollutant and all sources necessary to fulfill the requirements of the Clean Air Act for the state implementation plan, tribal implementation plan, or federal implementation plan to be reasonable controls with respect to all anthropogenic sources that have or may have contributed to the monitored exceedance or violation.
(vi) Where a State, tribal or federal air agency is obligated to revise its state implementation plan, tribal implementation plan, or federal implementation plan, the deference to enforceable control measures identified in paragraph (b)(8)(v) of this section shall remain only until the due date of the required state implementation plan, tribal implementation plan, or federal implementation plan revisions. However, where an air agency is obligated to revise the enforceable control measures identified in paragraph (b)(8)(v) of this section in its implementation plan as a result of an action pursuant to Clean Air Act section 110(k)(5), the deference, if any, to those enforceable control measures shall be determined on a case-by-case basis.
(vii) The Administrator shall not require a State to provide case-specific justification to support the not reasonably controllable or preventable criterion for emissions-generating activity that occurs outside of the State’s jurisdictional boundaries within which the concentration at issue was monitored. In the case of a tribe treated as a state under 40 CFR 49.2 with respect to exceptional events requirements, the tribe’s jurisdictional boundaries for purposes of requiring or directly implementing emission controls apply. In the case of a federal land manager or other federal agency submitting a demonstration under the requirements of this section, the jurisdictional boundaries that apply are those of the State or the tribe depending on which has jurisdiction over the area where the event has occurred.
(viii) In addition to the provisions that apply to specific event types identified in paragraphs (b)(3)(ii) and (b)(5)(i) through (iii) of this section in addressing the requirements set forth in paragraph (c)(3)(iv)(D) of this section regarding the not reasonably controllable or preventable criterion, the State must include the following components:
(A) Identification of the natural and anthropogenic sources of emissions causing and contributing to the monitored exceedance or violation, including the contribution from local sources.
(B) Identification of the relevant state implementation plan, tribal implementation plan, or federal implementation plan or other enforceable control measures in place for the sources identified in paragraph (b)(8)(vii)(A) of this section and the implementation status of these controls.
(C) Evidence of effective implementation and enforcement of the measures identified in paragraph (b)(8)(vii)(B) of this section.
(D) The provisions in this paragraph shall not apply if the provisions in paragraph (b)(4), (b)(5)(vi), or (b)(6) of this section apply.
(9) Mitigation plans. (i) Except as provided for in paragraph (b)(9)(ii) of this section, where a State is subject to the requirements of 40 CFR 51.930(b), the Administrator shall not place a concurrence flag in the appropriate field for the data record in the AQS database, as specified in paragraph (c)(2)(ii) of this section, if the data are of the type and pollutant that are the focus of the mitigation plan until the State fulfills its obligations under the requirements of 40 CFR 51.930(b). The Administrator may nonconcur or defer action on such a demonstration.
(ii) The prohibition on placing a concurrence flag in the appropriate field for the data record in the AQS database by the Administrator stated in paragraph (b)(9(i) of this section does not apply to data that are included in an exceptional events demonstration that is:
(A) submitted in accordance with paragraph (c)(3) of this section that is also of the type and pollutant that is the focus of the mitigation plan, and
(B) submitted within the 2-year period allowed for mitigation plan development as specified in 40 CFR 51.930(b)(3).
(c) Schedules and procedures—(1) Public notification. (i) In accordance with the mitigation requirement at 40 CFR 51.930(a)(1), all States and, where applicable, their political subdivisions must notify the public promptly whenever an event occurs or is reasonably anticipated to occur which may result in the exceedance of an applicable air quality standard.
(ii) [Reserved]
(2) Initial notification of potential exceptional event. (i) A State shall notify the Administrator of its intent to request exclusion of one or more measured exceedances of an applicable national ambient air quality standard as being due to an exceptional event by creating an initial event description and flagging the associated data that have been submitted to the AQS database and by engaging in the Initial Notification of Potential Exceptional Event process as follows:
(A) The State and the appropriate EPA Regional office shall engage in regular communications to identify those data that have been potentially influenced by an exceptional event, to determine whether the identified data may affect a regulatory determination and to discuss whether the State should develop and submit an exceptional events demonstration according to the requirements in this section;
(B) For data that may affect an anticipated regulatory determination or where circumstances otherwise compel the Administrator to prioritize the resulting demonstration, the Administrator shall respond to a State’s Initial Notification of Potential Exceptional Event with a due date for demonstration submittal that considers the nature of the event and the anticipated timing of the associated regulatory decision;
(C) The Administrator may waive the Initial Notification of Potential Exceptional Event process on a case-by-case basis.
(ii) The data shall not be excluded from determinations with respect to exceedances or violations of the national ambient air quality standards unless and until, following the State’s submittal of its demonstration pursuant to paragraph (c)(3) of this section and the Administrator’s review, the Administrator notifies the State of its concurrence by placing a concurrence flag in the appropriate field for the data record in the AQS database.
(iii) [Reserved]
(iv) [Reserved]
(v) [Reserved]
(vi) Table 2 to § 50.14 identifies the submission process for data that will or may influence the initial designation of areas for any new or revised national ambient air quality standard.
Table 2 to § 50.14—Schedule for Initial Notification and Demonstration Submission for Data Influenced by Exceptional Events for Use in Initial Area Designations
Exceptional events/Regulatory action | Condition | Exceptional events deadline schedule d |
---|---|---|
(A) Initial Notification deadline for data years 1, 2 and 3. a | If state and tribal initial designation recommendations for a new/revised national ambient air quality standard are due August through January, | then the Initial Notification deadline will be the July 1 prior to the recommendation deadline. |
(B) Initial Notification deadline for data years 1, 2 and 3. a | If state and tribal recommendations for a new/revised national ambient air quality standard are due February through July, | then the Initial Notification deadline will be the January 1 prior to the recommendation deadline. |
(C) Exceptional events demonstration submittal deadline for data years 1, 2 and 3 a | None | no later than the later of November 29, 2016 or the date that state and tribal recommendations are due to the Administrator. |
(D) Initial Notification and exceptional events demonstration submittal deadline for data year 4 b and, where applicable, data year 5. c | None | by the last day of the month that is 1 year and 7 months after promulgation of a new/revised national ambient air quality standard, unless either paragraph (E) or paragraph (F) applies. |
(E) Initial Notification and exceptional events demonstration submittal deadline for data year 4 b and, where applicable, data year 5. c | If the Administrator follows a 3-year designation schedule | the deadline is 2 years and 7 months after promulgation of a new/revised national ambient air quality standard. |
(F) Initial Notification and exceptional events demonstration submittal deadline for data year 4 b and, where applicable, data year 5. c | If the Administrator notifies the state/tribe that it intends to complete the initial area designations process according to a schedule between 2 and 3 years, | the deadline is 5 months prior to the date specified for final designations decisions in such Administrator notification. |
a Where data years 1, 2, and 3 are those years expected to be considered in state and tribal recommendations.
b Where data year 4 is the additional year of data that the Administrator may consider when making final area designations for a new/revised national ambient air quality standard under the standard designations schedule.
c Where data year 5 is the additional year of data that the Administrator may consider when making final area designations for a new/revised national ambient air quality standard under an extended designations schedule.
d The date by which air agencies must certify their ambient air quality monitoring data in AQS is annually on May 1 of the year following the year of data collection as specified in 40 CFR 58.15(a)(2). In some cases, however, air agencies may choose to certify a prior year’s data in advance of May 1 of the following year, particularly if the Administrator has indicated intent to promulgate final designations in the first 8 months of the calendar year. Exceptional events demonstration deadlines for “early certified” data will follow the deadlines for “year 4” and “year 5” data.
(3) Submission of demonstrations. (i) Except as provided under paragraph (c)(2)(vi) of this section, a State that has flagged data as being due to an exceptional event and is requesting exclusion of the affected measurement data shall, after notice and opportunity for public comment, submit a demonstration to justify data exclusion to the Administrator according to the schedule established under paragraph (c)(2)(i)(B).
(ii) [Reserved]
(iii) [Reserved]
(iv) The demonstration to justify data exclusion must include:
(A) A narrative conceptual model that describes the event(s) causing the exceedance or violation and a discussion of how emissions from the event(s) led to the exceedance or violation at the affected monitor(s);
(B) A demonstration that the event affected air quality in such a way that there exists a clear causal relationship between the specific event and the monitored exceedance or violation;
(C) Analyses comparing the claimed event-influenced concentration(s) to concentrations at the same monitoring site at other times to support the requirement at paragraph (c)(3)(iv)(B) of this section. The Administrator shall not require a State to prove a specific percentile point in the distribution of data;
(D) A demonstration that the event was both not reasonably controllable and not reasonably preventable; and
(E) A demonstration that the event was a human activity that is unlikely to recur at a particular location or was a natural event.
(v) With the submission of the demonstration containing the elements in paragraph (c)(3)(iv) of this section, the State must:
(A) Document that the State followed the public comment process and that the comment period was open for a minimum of 30 days, which could be concurrent with the beginning of the Administrator’s initial review period of the associated demonstration provided the State can meet all requirements in this paragraph;
(B) Submit the public comments it received along with its demonstration to the Administrator; and
(C) Address in the submission to the Administrator those comments disputing or contradicting factual evidence provided in the demonstration.
(vi) Where the State has submitted a demonstration according to the requirements of this section after September 30, 2016 and the Administrator has reviewed such demonstration and requested additional evidence to support one of the elements in paragraph (c)(3)(iv) of this section, the State shall have 12 months from the date of the Administrator’s request to submit such evidence. At the conclusion of this time, if the State has not submitted the requested additional evidence, the Administrator will notify the State in writing that it considers the demonstration to be inactive and will not pursue additional review of the demonstration. After a 12-month period of inactivity by the State, if a State desires to pursue the inactive demonstration, it must reinitiate its request to exclude associated data by following the process beginning with paragraph (c)(2)(i) of this section.
§ 50.15 National primary and secondary ambient air quality standards for ozone.
(a) The level of the national 8-hour primary and secondary ambient air quality standards for ozone (O
(b) The 8-hour primary and secondary O
§ 50.16 National primary and secondary ambient air quality standards for lead.
(a) The national primary and secondary ambient air quality standards for lead (Pb) and its compounds are 0.15 micrograms per cubic meter, arithmetic mean concentration over a 3-month period, measured in the ambient air as Pb either by:
(1) A reference method based on appendix G of this part and designated in accordance with part 53 of this chapter or;
(2) An equivalent method designated in accordance with part 53 of this chapter.
(b) The national primary and secondary ambient air quality standards for Pb are met when the maximum arithmetic 3-month mean concentration for a 3-year period, as determined in accordance with appendix R of this part, is less than or equal to 0.15 micrograms per cubic meter.
§ 50.17 National primary ambient air quality standards for sulfur oxides (sulfur dioxide).
(a) The level of the national primary 1-hour annual ambient air quality standard for oxides of sulfur is 75 parts per billion (ppb, which is 1 part in 1,000,000,000), measured in the ambient air as sulfur dioxide (SO
(b) The 1-hour primary standard is met at an ambient air quality monitoring site when the three-year average of the annual (99th percentile) of the daily maximum 1-hour average concentrations is less than or equal to 75 ppb, as determined in accordance with appendix T of this part.
(c) The level of the standard shall be measured by a reference method based on appendix A or A–1 of this part, or by a Federal Equivalent Method (FEM) designated in accordance with part 53 of this chapter.
§ 50.18 National primary ambient air quality standards for PM2.5 .
(a) The national primary ambient air quality standards for PM
(1) A reference method based on appendix L to this part and designated in accordance with part 53 of this chapter; or
(2) An equivalent method designated in accordance with part 53 of this chapter.
(b) The primary annual PM
(c) The primary 24-hour PM
§ 50.19 National primary and secondary ambient air quality standards for ozone.
(a) The level of the national 8-hour primary ambient air quality standard for ozone (O
(b) The 8-hour primary O
(c) The level of the national secondary ambient air quality standard for O
(d) The 8-hour secondary O
Appendix A–1 to Part 50—Reference Measurement Principle and Calibration Procedure for the Measurement of Sulfur Dioxide in the Atmosphere (Ultraviolet Fluorescence Method)
1.1 This ultraviolet fluorescence (UVF) method provides a measurement of the concentration of sulfur dioxide (SO
2.1 This reference method is based on automated measurement of the intensity of the characteristic fluorescence released by SO
2.2 The measurement system is calibrated by referencing the instrumental fluorescence measurements to SO
2.3 An analyzer implementing this measurement principle is shown schematically in Figure 1. Designs should include a measurement cell, a UV light source of appropriate wavelength, a UV detector system with appropriate wave length sensitivity, a pump and flow control system for sampling the ambient air and moving it into the measurement cell, sample air conditioning components as necessary to minimize measurement interferences, suitable control and measurement processing capability, and other apparatus as may be necessary. The analyzer must be designed to provide accurate, repeatable, and continuous measurements of SO
2.4 Sampling considerations: The use of a particle filter on the sample inlet line of a UVF SO
3.1 The effects of the principal potential interferences may need to be mitigated to meet the interference equivalent requirements of part 53 of this chapter. Aromatic hydrocarbons such as xylene and naphthalene can fluoresce and act as strong positive interferences. These gases can be removed by using a permeation type scrubber (hydrocarbon “kicker”). Nitrogen oxide (NO) in high concentrations can also fluoresce and cause positive interference. Optical filtering can be employed to improve the rejection of interference from high NO. Ozone can absorb UV light given off by the SO
Atmospheres containing accurately known concentrations of sulfur dioxide are prepared using a compressed gas transfer standard diluted with accurately metered clean air flow rates.
4.1 Apparatus: Figure 2 shows a typical generic system suitable for diluting a SO
4.1.1 SO
4.1.2 Dilution air flow control and measurement devices (or a combined device) capable of regulating and maintaining the air flow rate constant to within ±2 percent and measuring the air flow rate accurate to within ±2, properly calibrated to a NIST-traceable standard.
4.1.3 Mixing chamber, of an inert material such as glass and of proper design to provide thorough mixing of pollutant gas and diluent air streams.
4.1.4 Sampling manifold, constructed of glass, polytetrafluoroethylene (PTFE Teflon
4.1.5 Standard gas pressure regulator, of clean stainless steel with a stainless steel diaphragm, suitable for use with a high pressure SO
4.1.6.1 SO
4.1.6.2 Clean zero air, free of contaminants that could cause a detectable response or a change in sensitivity of the analyzer. Since ultraviolet fluorescence analyzers may be sensitive to aromatic hydrocarbons and O
4.2.1 Obtain a suitable calibration apparatus, such as the one shown schematically in Figure 1, and verify that all materials in contact with the pollutant are of glass, Teflon
4.2.2 Purge the SO
4.2.3 Ensure that there are no leaks in the system and that the flow measuring devices are properly and accurately calibrated under the conditions of use against a reliable volume or flow rate standard such as a soap-bubble meter or a wet-test meter traceable to a NIST standard. All volumetric flow rates should be corrected to the same reference temperature and pressure by using the formula below:
4.2.4 Allow the SO
4.2.5 Adjust the airflow to provide an SO
4.2.6 Calculate the actual SO
4.2.7 When the analyzer response has stabilized, adjust the SO
4.2.8 Adjust the flow rate(s) to provide several other SO
4.2.9 Plot the analyzer response (vertical or Y-axis) versus SO
Additional information on calibration and pollutant standards is provided in Section 12 of Reference 3.
The frequency of calibration, as well as the number of points necessary to establish the calibration curve and the frequency of other performance checking will vary by analyzer; however, the minimum frequency, acceptance criteria, and subsequent actions are specified in Reference 3, Appendix D: Measurement Quality Objectives and Validation Template for SO


Appendix A–2 to Part 50—Reference Method for the Determination of Sulfur Dioxide in the Atmosphere (Pararosaniline Method)
1.0 Applicability.
1.1 This method provides a measurement of the concentration of sulfur dioxide (SO
2.0 Principle.
2.1 A measured volume of air is bubbled through a solution of 0.04 M potassium tetrachloromercurate (TCM). The SO
(6) The optical density of this species is determined spectrophotometrically at 548 nm and is directly related to the amount of SO
3.0 Range.
3.1 The lower limit of detection of SO
4.0 Interferences.
4.1 The effects of the principal potential interferences have been minimized or eliminated in the following manner: Nitrogen oxides by the addition of sulfamic acid,(10, 11) heavy metals by the addition of ethylenediamine tetracetic acid disodium salt (EDTA) and phosphoric acid,(10, 12) and ozone by time delay.(10) Up to 60 µg Fe (III), 22 µg V (V), 10 µg Cu (II), 10 µg Mn (II), and 10 µg Cr (III) in 10 mL absorbing reagent can be tolerated in the procedure.(10) No significant interference has been encountered with 2.3 µg NH
5.0 Precision and Accuracy.
5.1 The precision of the analysis is 4.6 percent (at the 95 percent confidence level) based on the analysis of standard sulfite samples.(10)
5.2 Collaborative test results (14) based on the analysis of synthetic test atmospheres (SO
6.0 Stability.
6.1 By sampling in a controlled temperature environment of 15° ±10 °C, greater than 98.9 percent of the SO
7.0 Apparatus.
7.1 Sampling.
7.1.1 Sample probe: A sample probe meeting the requirements of section 7 of 40 CFR part 58, appendix E (Teflon ® or glass with residence time less than 20 sec.) is used to transport ambient air to the sampling train location. The end of the probe should be designed or oriented to preclude the sampling of precipitation, large particles, etc. A suitable probe can be constructed from Teflon ® tubing connected to an inverted funnel.
7.1.2 Absorber—short-term sampling: An all glass midget impinger having a solution capacity of 30 mL and a stem clearance of 4 ±1 mm from the bottom of the vessel is used for sampling periods of 30 minutes and 1 hour (or any period considerably less than 24 hours). Such an impinger is shown in Figure 1. These impingers are commercially available from distributors such as Ace Glass, Incorporated.
7.1.3 Absorber—24-hour sampling: A polypropylene tube 32 mm in diameter and 164 mm long (available from Bel Art Products, Pequammock, NJ) is used as the absorber. The cap of the absorber must be a polypropylene cap with two ports (rubber stoppers are unacceptable because the absorbing reagent can react with the stopper to yield erroneously high SO
7.1.4 Moisture trap: A moisture trap constructed of a glass trap as shown in Figure 1 or a polypropylene tube as shown in Figure 2 is placed between the absorber tube and flow control device to prevent entrained liquid from reaching the flow control device. The tube is packed with indicating silica gel as shown in Figure 2. Glass wool may be substituted for silica gel when collecting short-term samples (1 hour or less) as shown in Figure 1, or for long term (24 hour) samples if flow changes are not routinely encountered.
7.1.5 Cap seals: The absorber and moisture trap caps must seal securely to prevent leaks during use. Heat-shrink material as shown in Figure 2 can be used to retain the cap seals if there is any chance of the caps coming loose during sampling, shipment, or storage.


7.1.6 Flow control device: A calibrated rotameter and needle valve combination capable of maintaining and measuring air flow to within ±2 percent is suitable for short-term sampling but may not be used for long-term sampling. A critical orifice can be used for regulating flow rate for both long-term and short-term sampling. A 22-gauge hypodermic needle 25 mm long may be used as a critical orifice to yield a flow rate of approximately 1 L/min for a 30-minute sampling period. When sampling for 1 hour, a 23-gauge hypodermic needle 16 mm in length will provide a flow rate of approximately 0.5 L/min. Flow control for a 24-hour sample may be provided by a 27-gauge hypodermic needle critical orifice that is 9.5 mm in length. The flow rate should be in the range of 0.18 to 0.22 L/min.
7.1.7 Flow measurement device: Device calibrated as specified in 9.4.1 and used to measure sample flow rate at the monitoring site.
7.1.8 Membrane particle filter: A membrane filter of 0.8 to 2 µm porosity is used to protect the flow controller from particles during long-term sampling. This item is optional for short-term sampling.
7.1.9 Vacuum pump: A vacuum pump equipped with a vacuum gauge and capable of maintaining at least 70 kPa (0.7 atm) vacuum differential across the flow control device at the specified flow rate is required for sampling.
7.1.10 Temperature control device: The temperature of the absorbing solution during sampling must be maintained at 15° ±10 °C. As soon as possible following sampling and until analysis, the temperature of the collected sample must be maintained at 5° ±5 °C. Where an extended period of time may elapse before the collected sample can be moved to the lower storage temperature, a collection temperature near the lower limit of the 15 ±10 °C range should be used to minimize losses during this period. Thermoelectric coolers specifically designed for this temperature control are available commercially and normally operate in the range of 5° to 15 °C. Small refrigerators can be modified to provide the required temperature control; however, inlet lines must be insulated from the lower temperatures to prevent condensation when sampling under humid conditions. A small heating pad may be necessary when sampling at low temperatures (17)
7.1.11 Sampling train container: The absorbing solution must be shielded from light during and after sampling. Most commercially available sampler trains are enclosed in a light-proof box.
7.1.12 Timer: A timer is recommended to initiate and to stop sampling for the 24-hour period. The timer is not a required piece of equipment; however, without the timer a technician would be required to start and stop the sampling manually. An elapsed time meter is also recommended to determine the duration of the sampling period.
7.2 Shipping.
7.2.1 Shipping container: A shipping container that can maintain a temperature of 5° ±5 °C is used for transporting the sample from the collection site to the analytical laboratory. Ice coolers or refrigerated shipping containers have been found to be satisfactory. The use of eutectic cold packs instead of ice will give a more stable temperature control. Such equipment is available from Cole-Parmer Company, 7425 North Oak Park Avenue, Chicago, IL 60648.
7.3 Analysis.
7.3.1 Spectrophotometer: A spectrophotometer suitable for measurement of absorbances at 548 nm with an effective spectral bandwidth of less than 15 nm is required for analysis. If the spectrophotometer reads out in transmittance, convert to absorbance as follows:
A standard wavelength filter traceable to the National Bureau of Standards is used to verify the wavelength calibration according to the procedure enclosed with the filter. The wavelength calibration must be verified upon initial receipt of the instrument and after each 160 hours of normal use or every 6 months, whichever occurs first.
7.3.2 Spectrophotometer cells: A set of 1-cm path length cells suitable for use in the visible region is used during analysis. If the cells are unmatched, a matching correction factor must be determined according to Section 10.1.
7.3.3 Temperature control device: The color development step during analysis must be conducted in an environment that is in the range of 20° to 30 °C and controlled to ±1 °C. Both calibration and sample analysis must be performed under identical conditions (within 1 °C). Adequate temperature control may be obtained by means of constant temperature baths, water baths with manual temperature control, or temperature controlled rooms.
7.3.4 Glassware: Class A volumetric glassware of various capacities is required for preparing and standardizing reagents and standards and for dispensing solutions during analysis. These included pipets, volumetric flasks, and burets.
7.3.5 TCM waste receptacle: A glass waste receptacle is required for the storage of spent TCM solution. This vessel should be stoppered and stored in a hood at all times.
8.0 Reagents.
8.1 Sampling.
8.1.1 Distilled water: Purity of distilled water must be verified by the following procedure:(18)
8.1.2 Absorbing reagent (0.04 M potassium tetrachloromercurate [TCM]): Dissolve 10.86 g mercuric chloride, 0.066 g EDTA, and 6.0 g potassium chloride in distilled water and dilute to volume with distilled water in a 1,000-mL volumetric flask. (Caution: Mercuric chloride is highly poisonous. If spilled on skin, flush with water immediately.) The pH of this reagent should be between 3.0 and 5.0 (10) Check the pH of the absorbing solution by using pH indicating paper or a pH meter. If the pH of the solution is not between 3.0 and 5.0, dispose of the solution according to one of the disposal techniques described in Section 13.0. The absorbing reagent is normally stable for 6 months. If a precipitate forms, dispose of the reagent according to one of the procedures described in Section 13.0.
8.2 Analysis.
8.2.1 Sulfamic acid (0.6%): Dissolve 0.6 g sulfamic acid in 100 mL distilled water. Perpare fresh daily.
8.2.2 Formaldehyde (0.2%): Dilute 5 mL formaldehyde solution (36 to 38 percent) to 1,000 mL with distilled water. Prepare fresh daily.
8.2.3 Stock iodine solution (0.1 N): Place 12.7 g resublimed iodine in a 250-mL beaker and add 40 g potassium iodide and 25 mL water. Stir until dissolved, transfer to a 1,000 mL volumetric flask and dilute to volume with distilled water.
8.2.4 Iodine solution (0.01 N): Prepare approximately 0.01 N iodine solution by diluting 50 mL of stock iodine solution (Section 8.2.3) to 500 mL with distilled water.
8.2.5 Starch indicator solution: Triturate 0.4 g soluble starch and 0.002 g mercuric iodide (preservative) with enough distilled water to form a paste. Add the paste slowly to 200 mL of boiling distilled water and continue boiling until clear. Cool and transfer the solution to a glass stopperd bottle.
8.2.6 1 N hydrochloric acid: Slowly and while stirring, add 86 mL of concentrated hydrochloric acid to 500 mL of distilled water. Allow to cool and dilute to 1,000 mL with distilled water.
8.2.7 Potassium iodate solution: Accurately weigh to the nearest 0.1 mg, 1.5 g (record weight) of primary standard grade potassium iodate that has been previously dried at 180 °C for at least 3 hours and cooled in a dessicator. Dissolve, then dilute to volume in a 500-mL volumetric flask with distilled water.
8.2.8 Stock sodium thiosulfate solution (0.1 N): Prepare a stock solution by dissolving 25 g sodium thiosulfate (Na
8.2.9 Working sodium thiosulfate titrant (0.01 N): Accurately pipet 100 mL of stock sodium thiosulfate solution (Section 8.2.8) into a 1,000-mL volumetric flask and dilute to volume with freshly boiled, cooled, distilled water. Calculate the normality of the working sodium thiosulfate titrant (N
8.2.10 Standardized sulfite solution for the preparation of working sulfite-TCM solution: Dissolve 0.30 g sodium metabisulfite (Na
8.2.11 Working sulfite-TCM solution: Accurately pipet 5 mL of the standard sulfite solution (Section 8.2.10) into a 250-mL volumetric flask and dilute to volume with 0.04 M TCM. Calculate the concentration of sulfur dioxide in the working solution as follows:
This solution is stable for 30 days if kept at 5 °C. (16) If not kept at 5 °C, prepare fresh daily.
8.2.12 Purified pararosaniline (PRA) stock solution (0.2% nominal):
8.2.12.1 Dye specifications—
8.2.12.2 Preparation of stock PRA solution—A specially purified (99 to 100 percent pure) solution of pararosaniline, which meets the above specifications, is commercially available in the required 0.20 percent concentration (Harleco Co.). Alternatively, the dye may be purified, a stock solution prepared, and then assayed according to the procedure as described below.(10)
8.2.12.3 Purification procedure for PRA—
1. Place 100 mL each of 1-butanol and 1 N HCl in a large separatory funnel (250-mL) and allow to equilibrate. Note: Certain batches of 1-butanol contain oxidants that create an SO
2. Weigh 100 mg of pararosaniline hydrochloride dye (PRA) in a small beaker. Add 50 mL of the equilibrated acid (drain in acid from the bottom of the separatory funnel in 1.) to the beaker and let stand for several minutes. Discard the remaining acid phase in the separatory funnel.
3. To a 125-mL separatory funnel, add 50 mL of the equilibrated 1-butanol (draw the 1-butanol from the top of the separatory funnel in 1.). Transfer the acid solution (from 2.) containing the dye to the funnel and shake carefully to extract. The violet impurity will transfer to the organic phase.
4. Transfer the lower aqueous phase into another separatory funnel, add 20 mL of equilibrated 1-butanol, and extract again.
5. Repeat the extraction procedure with three more 10-mL portions of equilibrated 1-butanol.
6. After the final extraction, filter the acid phase through a cotton plug into a 50-mL volumetric flask and bring to volume with 1 N HCl. This stock reagent will be a yellowish red.
7. To check the purity of the PRA, perform the assay and adjustment of concentration (Section 8.2.12.4) and prepare a reagent blank (Section 11.2); the absorbance of this reagent blank at 540 nm should be less than 0.170 at 22 °C. If the absorbance is greater than 0.170 under these conditions, further extractions should be performed.
8.2.12.4 PRA assay procedure—The concentration of pararosaniline hydrochloride (PRA) need be assayed only once after purification. It is also recommended that commercial solutions of pararosaniline be assayed when first purchased. The assay procedure is as follows:(10)
1. Prepare 1 M acetate-acetic acid buffer stock solution with a pH of 4.79 by dissolving 13.61 g of sodium acetate trihydrate in distilled water in a 100-mL volumetric flask. Add 5.70 mL of glacial acetic acid and dilute to volume with distilled water.
2. Pipet 1 mL of the stock PRA solution obtained from the purification process or from a commercial source into a 100-mL volumetric flask and dilute to volume with distilled water.
3. Transfer a 5–mL aliquot of the diluted PRA solution from 2. into a 50–mL volumetric flask. Add 5mL of 1 M acetate-acetic acid buffer solution from 1. and dilute the mixture to volume with distilled water. Let the mixture stand for 1 hour.
4. Measure the absorbance of the above solution at 540 nm with a spectrophotometer against a distilled water reference. Compute the percentage of nominal concentration of PRA by
8.2.13 Pararosaniline reagent: To a 250–mL volumetric flask, add 20 mL of stock PRA solution. Add an additional 0.2 mL of stock solution for each percentage that the stock assays below 100 percent. Then add 25 mL of 3 M phosphoric acid and dilute to volume with distilled water. The reagent is stable for at least 9 months. Store away from heat and light.
9.0 Sampling Procedure.
9.1 General Considerations. Procedures are described for short-term sampling (30-minute and 1-hour) and for long-term sampling (24-hour). Different combinations of absorbing reagent volume, sampling rate, and sampling time can be selected to meet special needs. For combinations other than those specifically described, the conditions must be adjusted so that linearity is maintained between absorbance and concentration over the dynamic range. Absorbing reagent volumes less than 10 mL are not recommended. The collection efficiency is above 98 percent for the conditions described; however, the efficiency may be substantially lower when sampling concentrations below 25 µγSO
9.2 30-Minute and 1-Hour Sampling. Place 10 mL of TCM absorbing reagent in a midget impinger and seal the impinger with a thin film of silicon stopcock grease (around the ground glass joint). Insert the sealed impinger into the sampling train as shown in Figure 1, making sure that all connections between the various components are leak tight. Greaseless ball joint fittings, heat shrinkable Teflon ® tubing, or Teflon ® tube fittings may be used to attain leakfree conditions for portions of the sampling train that come into contact with air containing SO
9.3 24-Hour Sampling. Place 50 mL of TCM absorbing solution in a large absorber, close the cap, and, if needed, apply the heat shrink material as shown in Figure 3. Verify that the reagent level is at the 50 mL mark on the absorber. Insert the sealed absorber into the sampling train as shown in Figure 2. At this time verify that the absorber temperature is controlled to 15 ±10 °C. During sampling, the absorber temperature must be controlled to prevent decomposition of the collected complex. From the onset of sampling until analysis, the absorbing solution must be protected from direct sunlight. Determine the flow rate according to Section 9.4.2. Collect the sample for 24 hours from midnight to midnight at a flow rate of 0.200 ±0.020 L/min. A start/stop timer is helpful for initiating and stopping sampling and an elapsed time meter will be useful for determining the sampling time.

9.4 Flow Measurement.
9.4.1 Calibration: Flow measuring devices used for the on-site flow measurements required in 9.4.2 must be calibrated against a reliable flow or volume standard such as an NBS traceable bubble flowmeter or calibrated wet test meter. Rotameters or critical orifices used in the sampling train may be calibrated, if desired, as a quality control check, but such calibration shall not replace the on-site flow measurements required by 9.4.2. In-line rotameters, if they are to be calibrated, should be calibrated in situ, with the appropriate volume of solution in the absorber.
9.4.2 Determination of flow rate at sampling site: For short-term samples, the standard flow rate is determined at the sampling site at the initiation and completion of sample collection with a calibrated flow measuring device connected to the inlet of the absorber. For 24-hour samples, the standard flow rate is determined at the time the absorber is placed in the sampling train and again when the absorber is removed from the train for shipment to the analytical laboratory with a calibrated flow measuring device connected to the inlet of the sampling train. The flow rate determination must be made with all components of the sampling system in operation (e.g., the absorber temperature controller and any sample box heaters must also be operating). Equation 6 may be used to determine the standard flow rate when a calibrated positive displacement meter is used as the flow measuring device. Other types of calibrated flow measuring devices may also be used to determine the flow rate at the sampling site provided that the user applies any appropriate corrections to devices for which output is dependent on temperature or pressure.
If a barometer is not available, the following equation may be used to determine the barometric pressure:
If the initial flow rate (Q
Invalidate the sample if the difference between the initial (Q
9.5 Sample Storage and Shipment. Remove the impinger or absorber from the sampling train and stopper immediately. Verify that the temperature of the absorber is not above 25 °C. Mark the level of the solution with a temporary (e.g., grease pencil) mark. If the sample will not be analyzed within 12 hours of sampling, it must be stored at 5° ±5 °C until analysis. Analysis must occur within 30 days. If the sample is transported or shipped for a period exceeding 12 hours, it is recommended that thermal coolers using eutectic ice packs, refrigerated shipping containers, etc., be used for periods up to 48 hours. (17) Measure the temperature of the absorber solution when the shipment is received. Invalidate the sample if the temperature is above 10 °C. Store the sample at 5° ±5 °C until it is analyzed.
10.0 Analytical Calibration.
10.1 Spectrophotometer Cell Matching. If unmatched spectrophotometer cells are used, an absorbance correction factor must be determined as follows:
1. Fill all cells with distilled water and designate the one that has the lowest absorbance at 548 nm as the reference. (This reference cell should be marked as such and continually used for this purpose throughout all future analyses.)
2. Zero the spectrophotometer with the reference cell.
3. Determine the absorbance of the remaining cells (A
The corrected absorbance during future analyses using each cell is determining as follows:
10.2 Static Calibration Procedure (Option 1). Prepare a dilute working sulfite-TCM solution by diluting 10 mL of the working sulfite-TCM solution (Section 8.2.11) to 100 mL with TCM absorbing reagent. Following the table below, accurately pipet the indicated volumes of the sulfite-TCM solutions into a series of 25-mL volumetric flasks. Add TCM absorbing reagent as indicated to bring the volume in each flask to 10 mL.
Sulfite-TCM solution | Volume of sulfite-TCM solution | Volume of TCM, mL | Total µg SO |
---|---|---|---|
Working | 4.0 | 6.0 | 28.8 |
Working | 3.0 | 7.0 | 21.6 |
Working | 2.0 | 8.0 | 14.4 |
Dilute working | 10.0 | 0.0 | 7.2 |
Dilute working | 5.0 | 5.0 | 3.6 |
0.0 | 10.0 | 0.0 |
*Based on working sulfite-TCM solution concentration of 7.2 µg SO
To each volumetric flask, add 1 mL 0.6% sulfamic acid (Section 8.2.1), accurately pipet 2 mL 0.2% formaldehyde solution (Section 8.2.2), then add 5 mL pararosaniline solution (Section 8.2.13). Start a laboratory timer that has been set for 30 minutes. Bring all flasks to volume with recently boiled and cooled distilled water and mix thoroughly. The color must be developed (during the 30-minute period) in a temperature environment in the range of 20° to 30 °C, which is controlled to ±1 °C. For increased precision, a constant temperature bath is recommended during the color development step. After 30 minutes, determine the corrected absorbance of each standard at 548 nm against a distilled water reference (Section 10.1). Denote this absorbance as (A). Distilled water is used in the reference cell rather than the reagant blank because of the temperature sensitivity of the reagent blank. Calculate the total micrograms SO
A calibration equation is determined using the method of linear least squares (Section 12.1). The total micrograms SO
10.3 Dynamic Calibration Procedures (Option 2). Atmospheres containing accurately known concentrations of sulfur dioxide are prepared using permeation devices. In the systems for generating these atmospheres, the permeation device emits gaseous SO
10.3.1 Calibration Option 2A (30-minute and 1-hour samples): Generate a series of six standard atmospheres of SO

Be sure that the total flow rate of the standard exceeds the flow demand of the sample train, with the excess flow vented at atmospheric pressure. Sample each atmosphere using similar apparatus as shown in Figure 1 and under the same conditions as field sampling (i.e., use same absorbing reagent volume and sample same volume of air at an equivalent flow rate). Due to the length of the sampling periods required, this method is not recommended for 24-hour sampling. At the completion of sampling, quantitatively transfer the contents of each impinger to one of a series of 25-mL volumetric flasks (if 10 mL of absorbing solution was used) using small amounts of distilled water for rinse (10 mL of absorbing solution was used, bring the absorber solution in each impinger to orginal volume with distilled H
Add the remaining reagents for color development in the same manner as in Section 10.2 for static solutions. Calculate a calibration equation and a calibration factor (B
10.3.2 Calibration Option 2B (24-hour samples): Generate a standard atmosphere containing approximately 1,050 µg SO
At the completion of sampling, bring the absorber solutions to original volume with distilled water. Pipet a 10-mL portion from each absorber into one of a series of 25-mL volumetric flasks. If the color development steps are not to be started within 12 hours of sampling, store the solutions at 5° ±5 °C. Add the remaining reagents for color development in the same manner as in Section 10.2 for static solutions. Calculate the total µg SO
Calculate a calibration equation and a calibration factor (B
11.0 Sample Preparation and Analysis.
11.1 Sample Preparation. Remove the samples from the shipping container. If the shipment period exceeded 12 hours from the completion of sampling, verify that the temperature is below 10 °C. Also, compare the solution level to the temporary level mark on the absorber. If either the temperature is above 10 °C or there was significant loss (more than 10 mL) of the sample during shipping, make an appropriate notation in the record and invalidate the sample. Prepare the samples for analysis as follows:
1. For 30-minute or 1-hour samples: Quantitatively transfer the entire 10 mL amount of absorbing solution to a 25-mL volumetric flask and rinse with a small amount (
2. For 24-hour samples: If the volume of the sample is less than the original 50-mL volume (permanent mark on the absorber), adjust the volume back to the original volume with distilled water to compensate for water lost to evaporation during sampling. If the final volume is greater than the original volume, the volume must be measured using a graduated cylinder. To analyze, pipet 10 mL of the solution into a 25-mL volumetric flask.
11.2 Sample Analysis. For each set of determinations, prepare a reagent blank by adding 10 mL TCM absorbing solution to a 25-mL volumetric flask, and two control standards containing approximately 5 and 15 µg SO
1. Allow the sample to stand 20 minutes after the completion of sampling to allow any ozone to decompose (if applicable).
2. To each 25-mL volumetric flask containing reagent blank, sample, or control standard, add 1 mL of 0.6% sulfamic acid (Section 8.2.1) and allow to react for 10 min.
3. Accurately pipet 2 mL of 0.2% formaldehyde solution (Section 8.2.2) and then 5 mL of pararosaniline solution (Section 8.2.13) into each flask. Start a laboratory timer set at 30 minutes.
4. Bring each flask to volume with recently boiled and cooled distilled water and mix thoroughly.
5. During the 30 minutes, the solutions must be in a temperature controlled environment in the range of 20° to 30 °C maintained to ±1 °C. This temperature must also be within 1 °C of that used during calibration.
6. After 30 minutes and before 60 minutes, determine the corrected absorbances (equation 10) of each solution at 548 nm using 1-cm optical path length cells against a distilled water reference (Section 10.1). (Distilled water is used as a reference instead of the reagent blank because of the sensitivity of the reagent blank to temperature.)
7. Do not allow the colored solution to stand in the cells because a film may be deposited. Clean the cells with isopropyl alcohol after use.
8. The reagent blank must be within 0.03 absorbance units of the intercept of the calibration equation determined in Section 10.
11.3 Absorbance range. If the absorbance of the sample solution ranges between 1.0 and 2.0, the sample can be diluted 1:1 with a portion of the reagent blank and the absorbance redetermined within 5 minutes. Solutions with higher absorbances can be diluted up to sixfold with the reagent blank in order to obtain scale readings of less than 1.0 absorbance unit. However, it is recommended that a smaller portion (
11.4 Reagent disposal. All reagents containing mercury compounds must be stored and disposed of using one of the procedures contained in Section 13. Until disposal, the discarded solutions can be stored in closed glass containers and should be left in a fume hood.
12.0 Calculations.
12.1 Calibration Slope, Intercept, and Correlation Coefficient. The method of least squares is used to calculate a calibration equation in the form of:
The slope (m), intercept (b), and correlation coefficient (r) are calculated as follows:
A data form (Figure 5) is supplied for easily organizing calibration data when the slope, intercept, and correlation coefficient are calculated by hand.
12.2 Total Sample Volume. Determine the sampling volume at standard conditions as follows:
12.3 Sulfur Dioxide Concentration. Calculate and report the concentration of each sample as follows:
Data Form
[For hand calculations]
Calibration point no. | Micro- grams So | Absor- bance units | |||
---|---|---|---|---|---|
(x) | (y) | x 2 | xy | y 2 | |
1 | |||||
2 | |||||
3 | |||||
4 | |||||
5 | |||||
6 |
12.4 Control Standards. Calculate the analyzed micrograms of SO
The difference between the true and analyzed values of the control standards must not be greater than 1 µg. If the difference is greater than 1 µg, the source of the discrepancy must be identified and corrected.
12.5 Conversion of µg/m
13.0 The TCM absorbing solution and any reagents containing mercury compounds must be treated and disposed of by one of the methods discussed below. Both methods remove greater than 99.99 percent of the mercury.
13.1 Disposal of Mercury-Containing Solutions.
13.2 Method for Forming an Amalgam.
1. Place the waste solution in an uncapped vessel in a hood.
2. For each liter of waste solution, add approximately 10 g of sodium carbonate until neutralization has occurred (NaOH may have to be used).
3. Following neutralization, add 10 g of granular zinc or magnesium.
4. Stir the solution in a hood for 24 hours. Caution must be exercised as hydrogen gas is evolved by this treatment process.
5. After 24 hours, allow the solution to stand without stirring to allow the mercury amalgam (solid black material) to settle to the bottom of the waste receptacle.
6. Upon settling, decant and discard the supernatant liquid.
7. Quantitatively transfer the solid material to a container and allow to dry.
8. The solid material can be sent to a mercury reclaiming plant. It must not be discarded.
13.3 Method Using Aluminum Foil Strips.
1. Place the waste solution in an uncapped vessel in a hood.
2. For each liter of waste solution, add approximately 10 g of aluminum foil strips. If all the aluminum is consumed and no gas is evolved, add an additional 10 g of foil. Repeat until the foil is no longer consumed and allow the gas to evolve for 24 hours.
3. Decant the supernatant liquid and discard.
4. Transfer the elemental mercury that has settled to the bottom of the vessel to a storage container.
5. The mercury can be sent to a mercury reclaiming plant. It must not be discarded.
14.0 References for SO
1. Quality Assurance Handbook for Air Pollution Measurement Systems, Volume I, Principles. EPA–600/9–76–005, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, 1976.
2. Quality Assurance Handbook for Air Pollution Measurement Systems, Volume II, Ambient Air Specific Methods. EPA–600/4–77–027a, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, 1977.
3. Dasqupta, P. K., and K. B. DeCesare. Stability of Sulfur Dioxide in Formaldehyde and Its Anomalous Behavior in Tetrachloromercurate (II). Submitted for publication in Atmospheric Environment, 1982.
4. West, P. W., and G. C. Gaeke. Fixation of Sulfur Dioxide as Disulfitomercurate (II) and Subsequent Colorimetric Estimation. Anal. Chem., 28:1816, 1956.
5. Ephraim, F. Inorganic Chemistry. P. C. L. Thorne and E. R. Roberts, Eds., 5th Edition, Interscience, 1948, p. 562.
6. Lyles, G. R., F. B. Dowling, and V. J. Blanchard. Quantitative Determination of Formaldehyde in the Parts Per Hundred Million Concentration Level. J. Air. Poll. Cont. Assoc., Vol. 15(106), 1965.
7. McKee, H. C., R. E. Childers, and O. Saenz, Jr. Collaborative Study of Reference Method for Determination of Sulfur Dioxide in the Atmosphere (Pararosaniline Method). EPA-APTD-0903, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, September 1971.
8. Urone, P., J. B. Evans, and C. M. Noyes. Tracer Techniques in Sulfur—Air Pollution Studies Apparatus and Studies of Sulfur Dioxide Colorimetric and Conductometric Methods. Anal. Chem., 37: 1104, 1965.
9. Bostrom, C. E. The Absorption of Sulfur Dioxide at Low Concentrations (pphm) Studied by an Isotopic Tracer Method. Intern. J. Air Water Poll., 9:333, 1965.
10. Scaringelli, F. P., B. E. Saltzman, and S. A. Frey. Spectrophotometric Determination of Atmospheric Sulfur Dioxide. Anal. Chem., 39: 1709, 1967.
11. Pate, J. B., B. E. Ammons, G. A. Swanson, and J. P. Lodge, Jr. Nitrite Interference in Spectrophotometric Determination of Atmospheric Sulfur Dioxide. Anal. Chem., 37:942, 1965.
12. Zurlo, N., and A. M. Griffini. Measurement of the Sulfur Dioxide Content of the Air in the Presence of Oxides of Nitrogen and Heavy Metals. Medicina Lavoro, 53:330, 1962.
13. Rehme, K. A., and F. P. Scaringelli. Effect of Ammonia on the Spectrophotometric Determination of Atmospheric Concentrations of Sulfur Dioxide. Anal. Chem., 47:2474, 1975.
14. McCoy, R. A., D. E. Camann, and H. C. McKee. Collaborative Study of Reference Method for Determination of Sulfur Dioxide in the Atmosphere (Pararosaniline Method) (24-Hour Sampling). EPA–650/4–74–027, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, December 1973.
15. Fuerst, R. G. Improved Temperature Stability of Sulfur Dioxide Samples Collected by the Federal Reference Method. EPA–600/4–78–018, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, April 1978.
16. Scaringelli, F. P., L. Elfers, D. Norris, and S. Hochheiser. Enhanced Stability of Sulfur Dioxide in Solution. Anal. Chem., 42:1818, 1970.
17. Martin, B. E. Sulfur Dioxide Bubbler Temperature Study. EPA–600/4–77–040, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, August 1977.
18. American Society for Testing and Materials. ASTM Standards, Water; Atmospheric Analysis. Part 23. Philadelphia, PA, October 1968, p. 226.
19. O’Keeffe, A. E., and G. C. Ortman. Primary Standards for Trace Gas Analysis. Anal. Chem., 38:760, 1966.
20. Scaringelli, F. P., S. A. Frey, and B. E. Saltzman. Evaluation of Teflon Permeation Tubes for Use with Sulfur Dioxide. Amer. Ind. Hygiene Assoc. J., 28:260, 1967.
21. Scaringelli, F. P., A. E. O’Keeffe, E. Rosenberg, and J. P. Bell, Preparation of Known Concentrations of Gases and Vapors With Permeation Devices Calibrated Gravimetrically. Anal. Chem., 42:871, 1970.
22. A Procedure for Establishing Traceability of Gas Mixtures to Certain National Bureau of Standards Standard Reference Materials. EPA–600/7–81–010, U.S. Environmental Protection Agency, Environmental Monitoring Systems Laboratory (MD–77), Research Triangle Park, NC 27711, January 1981.
Appendix B to Part 50—Reference Method for the Determination of Suspended Particulate Matter in the Atmosphere (High-Volume Method)
1.0 Applicability.
1.1 This method provides a measurement of the mass concentration of total suspended particulate matter (TSP) in ambient air for determining compliance with the primary and secondary national ambient air quality standards for particulate matter as specified in § 50.6 and § 50.7 of this chapter. The measurement process is nondestructive, and the size of the sample collected is usually adequate for subsequent chemical analysis. Quality assurance procedures and guidance are provided in part 58, appendixes A and B, of this chapter and in References 1 and 2.
2.0 Principle.
2.1 An air sampler, properly located at the measurement site, draws a measured quantity of ambient air into a covered housing and through a filter during a 24-hr (nominal) sampling period. The sampler flow rate and the geometry of the shelter favor the collection of particles up to 25–50 µm (aerodynamic diameter), depending on wind speed and direction.(3) The filters used are specified to have a minimum collection efficiency of 99 percent for 0.3 µm (DOP) particles (see Section 7.1.4).
2.2 The filter is weighed (after moisture equilibration) before and after use to determine the net weight (mass) gain. The total volume of air sampled, corrected to EPA standard conditions (25 °C, 760 mm Hg [101 kPa]), is determined from the measured flow rate and the sampling time. The concentration of total suspended particulate matter in the ambient air is computed as the mass of collected particles divided by the volume of air sampled, corrected to standard conditions, and is expressed in micrograms per standard cubic meter (µg/std m
3.0 Range.
3.1 The approximate concentration range of the method is 2 to 750 µg/std m
3.2 At wind speeds between 1.3 and 4.5 m/sec (3 and 10 mph), the high-volume air sampler has been found to collect particles up to 25 to 50 µm, depending on wind speed and direction.(3) For the filter specified in Section 7.1, there is effectively no lower limit on the particle size collected.
4.0 Precision.
4.1 Based upon collaborative testing, the relative standard deviation (coefficient of variation) for single analyst precision (repeatability) of the method is 3.0 percent. The corresponding value for interlaboratory precision (reproducibility) is 3.7 percent.(4)
5.0 Accuracy.
5.1 The absolute accuracy of the method is undefined because of the complex nature of atmospheric particulate matter and the difficulty in determining the “true” particulate matter concentration. This method provides a measure of particulate matter concentration suitable for the purpose specified under Section 1.0, Applicability.
6.0 Inherent Sources of Error.
6.1 Airflow variation. The weight of material collected on the filter represents the (integrated) sum of the product of the instantaneous flow rate times the instantaneous particle concentration. Therefore, dividing this weight by the average flow rate over the sampling period yields the true particulate matter concentration only when the flow rate is constant over the period. The error resulting from a nonconstant flow rate depends on the magnitude of the instantaneous changes in the flow rate and in the particulate matter concentration. Normally, such errors are not large, but they can be greatly reduced by equipping the sampler with an automatic flow controlling mechanism that maintains constant flow during the sampling period. Use of a contant flow controller is recommended.*
*At elevated altitudes, the effectiveness of automatic flow controllers may be reduced because of a reduction in the maximum sampler flow.
6.2 Air volume measurement. If the flow rate changes substantially or nonuniformly during the sampling period, appreciable error in the estimated air volume may result from using the average of the presampling and postsampling flow rates. Greater air volume measurement accuracy may be achieved by (1) equipping the sampler with a flow controlling mechanism that maintains constant air flow during the sampling period,* (2) using a calibrated, continuous flow rate recording device to record the actual flow rate during the samping period and integrating the flow rate over the period, or (3) any other means that will accurately measure the total air volume sampled during the sampling period. Use of a continuous flow recorder is recommended, particularly if the sampler is not equipped with a constant flow controller.
6.3 Loss of volatiles. Volatile particles collected on the filter may be lost during subsequent sampling or during shipment and/or storage of the filter prior to the postsampling weighing.(5) Although such losses are largely unavoidable, the filter should be reweighed as soon after sampling as practical.
6.4 Artifact particulate matter. Artifact particulate matter can be formed on the surface of alkaline glass fiber filters by oxidation of acid gases in the sample air, resulting in a higher than true TSP determination.(6 7) This effect usually occurs early in the sample period and is a function of the filter pH and the presence of acid gases. It is generally believed to account for only a small percentage of the filter weight gain, but the effect may become more significant where relatively small particulate weights are collected.
6.5 Humidity. Glass fiber filters are comparatively insensitive to changes in relative humidity, but collected particulate matter can be hygroscopic.(8) The moisture conditioning procedure minimizes but may not completely eliminate error due to moisture.
6.6 Filter handling. Careful handling of the filter between the presampling and postsampling weighings is necessary to avoid errors due to loss of fibers or particles from the filter. A filter paper cartridge or cassette used to protect the filter can minimize handling errors. (See Reference 2, Section 2).
6.7 Nonsampled particulate matter. Particulate matter may be deposited on the filter by wind during periods when the sampler is inoperative. (9) It is recommended that errors from this source be minimized by an automatic mechanical device that keeps the filter covered during nonsampling periods, or by timely installation and retrieval of filters to minimize the nonsampling periods prior to and following operation.
6.8 Timing errors. Samplers are normally controlled by clock timers set to start and stop the sampler at midnight. Errors in the nominal 1,440-min sampling period may result from a power interruption during the sampling period or from a discrepancy between the start or stop time recorded on the filter information record and the actual start or stop time of the sampler. Such discrepancies may be caused by (1) poor resolution of the timer set-points, (2) timer error due to power interruption, (3) missetting of the timer, or (4) timer malfunction. In general, digital electronic timers have much better set-point resolution than mechanical timers, but require a battery backup system to maintain continuity of operation after a power interruption. A continuous flow recorder or elapsed time meter provides an indication of the sampler run-time, as well as indication of any power interruption during the sampling period and is therefore recommended.
6.9 Recirculation of sampler exhaust. Under stagnant wind conditions, sampler exhaust air can be resampled. This effect does not appear to affect the TSP measurement substantially, but may result in increased carbon and copper in the collected sample. (10) This problem can be reduced by ducting the exhaust air well away, preferably downwind, from the sampler.
7.0 Apparatus.
(See References 1 and 2 for quality assurance information.)
Samplers purchased prior to the effective date of this amendment are not subject to specifications preceded by (†).
7.1 Filter. (Filters supplied by the Environmental Protection Agency can be assumed to meet the following criteria. Additional specifications are required if the sample is to be analyzed chemically.)
7.1.1 Size: 20.3 ±0.2 × 25.4 ±0.2 cm (nominal 8 × 10 in).
7.1.2 Nominal exposed area: 406.5 cm
7.1.3. Material: Glass fiber or other relatively inert, nonhygroscopic material. (8)
7.1.4 Collection efficiency: 99 percent minimum as measured by the DOP test (ASTM–2986) for particles of 0.3 µm diameter.
7.1.5 Recommended pressure drop range: 42–54 mm Hg (5.6–7.2 kPa) at a flow rate of 1.5 std m
7.1.6 pH: 6 to 10. (11)
7.1.7 Integrity: 2.4 mg maximum weight loss. (11)
7.1.8 Pinholes: None.
7.1.9 Tear strength: 500 g minimum for 20 mm wide strip cut from filter in weakest dimension. (See ASTM Test D828–60).
7.1.10 Brittleness: No cracks or material separations after single lengthwise crease.
7.2 Sampler. The air sampler shall provide means for drawing the air sample, via reduced pressure, through the filter at a uniform face velocity.
7.2.1 The sampler shall have suitable means to:
a. Hold and seal the filter to the sampler housing.
b. Allow the filter to be changed conveniently.
c. Preclude leaks that would cause error in the measurement of the air volume passing through the filter.
d. (†)
(†) See note at beginning of Section 7 of this appendix.
7.2.2 Minimum sample flow rate, heavily loaded filter: 1.1 m
‡ These specifications are in actual air volume units; to convert to EPA standard air volume units, multiply the specifications by (P
7.2.3 Maximum sample flow rate, clean filter: 1.7 m
7.2.4 Blower Motor: The motor must be capable of continuous operation for 24-hr periods.
7.3 Sampler shelter.
7.3.1 The sampler shelter shall:
a. Maintain the filter in a horizontal position at least 1 m above the sampler supporting surface so that sample air is drawn downward through the filter.
b. Be rectangular in shape with a gabled roof, similar to the design shown in Figure 1.
c. Cover and protect the filter and sampler from precipitation and other weather.
d. Discharge exhaust air at least 40 cm from the sample air inlet.
e. Be designed to minimize the collection of dust from the supporting surface by incorporating a baffle between the exhaust outlet and the supporting surface.
7.3.2 The sampler cover or roof shall overhang the sampler housing somewhat, as shown in Figure 1, and shall be mounted so as to form an air inlet gap between the cover and the sampler housing walls.
7.4 Flow rate measurement devices.
7.4.1 The sampler shall incorporate a flow rate measurement device capable of indicating the total sampler flow rate. Two common types of flow indicators covered in the calibration procedure are (1) an electronic mass flowmeter and (2) an orifice or orifices located in the sample air stream together with a suitable pressure indicator such as a manometer, or aneroid pressure gauge. A pressure recorder may be used with an orifice to provide a continuous record of the flow. Other types of flow indicators (including rotameters) having comparable precision and accuracy are also acceptable.
7.4.2 † The flow rate measurement device must be capable of being calibrated and read in units corresponding to a flow rate which is readable to the nearest 0.02 std m
7.5 Thermometer, to indicate the approximate air temperature at the flow rate measurement orifice, when temperature corrections are used.
7.5.1 Range: −40° to + 50 °C (223–323 K).
7.5.2 Resolution: 2 °C (2 K).
7.6 Barometer, to indicate barometric pressure at the flow rate measurement orifice, when pressure corrections are used.
7.6.1 Range: 500 to 800 mm Hg (66–106 kPa).
7.6.2 Resolution: ±5 mm Hg (0.67 kPa).
7.7 Timing/control device.
7.7.1 The timing device must be capable of starting and stopping the sampler to obtain an elapsed run-time of 24 hr ±1 hr (1,440 ±60 min).
7.7.2 Accuracy of time setting: ±30 min, or better. (See Section 6.8).
7.8 Flow rate transfer standard, traceable to a primary standard. (See Section 9.2.)
7.8.1 Approximate range: 1.0 to 1.8 m
7.8.2 Resolution: 0.02 m
7.8.3 Reproducibility: ±2 percent (2 times coefficient of variation) over normal ranges of ambient temperature and pressure for the stated flow rate range. (See Reference 2, Section 2.)
7.8.4 Maximum pressure drop at 1.7 std m
7.8.5 The flow rate transfer standard must connect without leaks to the inlet of the sampler and measure the flow rate of the total air sample.
7.8.6 The flow rate transfer standard must include a means to vary the sampler flow rate over the range of 1.0 to 1.8 m
7.8.7 The conventional type of flow transfer standard consists of: An orifice unit with adapter that connects to the inlet of the sampler, a manometer or other device to measure orifice pressure drop, a means to vary the flow through the sampler unit, a thermometer to measure the ambient temperature, and a barometer to measure ambient pressure. Two such devices are shown in Figures 2a and 2b. Figure 2a shows multiple fixed resistance plates, which necessitate disassembly of the unit each time the flow resistance is changed. A preferable design, illustrated in Figure 2b, has a variable flow restriction that can be adjusted externally without disassembly of the unit. Use of a conventional, orifice-type transfer standard is assumed in the calibration procedure (Section 9). However, the use of other types of transfer standards meeting the above specifications, such as the one shown in Figure 2c, may be approved; see the note following Section 9.1.
7.9 Filter conditioning environment
7.9.1 Controlled temperature: between 15° and 30 °C with less than ±3 °C variation during equilibration period.
7.9.2 Controlled humidity: Less than 50 percent relative humidity, constant within ±5 percent.
7.10 Analytical balance.
7.10.1 Sensitivity: 0.1 mg.
7.10.2 Weighing chamber designed to accept an unfolded 20.3 × 25.4 cm (8 × 10 in) filter.
7.11 Area light source, similar to X-ray film viewer, to backlight filters for visual inspection.
7.12 Numbering device, capable of printing identification numbers on the filters before they are placed in the filter conditioning environment, if not numbered by the supplier.
8.0 Procedure.
(See References 1 and 2 for quality assurance information.)
8.1 Number each filter, if not already numbered, near its edge with a unique identification number.
8.2 Backlight each filter and inspect for pinholes, particles, and other imperfections; filters with visible imperfections must not be used.
8.3 Equilibrate each filter in the conditioning environment for at least 24-hr.
8.4 Following equilibration, weigh each filter to the nearest milligram and record this tare weight (W
8.5 Do not bend or fold the filter before collection of the sample.
8.6 Open the shelter and install a numbered, preweighed filter in the sampler, following the sampler manufacturer’s instructions. During inclement weather, precautions must be taken while changing filters to prevent damage to the clean filter and loss of sample from or damage to the exposed filter. Filter cassettes that can be loaded and unloaded in the laboratory may be used to minimize this problem (See Section 6.6).
8.7 Close the shelter and run the sampler for at least 5 min to establish run-temperature conditions.
8.8 Record the flow indicator reading and, if needed, the barometric pressure (P
8.9 Record the sampler identification information (filter number, site location or identification number, sample date, and starting time).
8.10 Set the timer to start and stop the sampler such that the sampler runs 24-hrs, from midnight to midnight (local time).
8.11 As soon as practical following the sampling period, run the sampler for at least 5 min to again establish run-temperature conditions.
8.12 Record the flow indicator reading and, if needed, the barometric pressure (P
No onsite pressure or temperature measurements are necessary if the sampler flow indicator does not require pressure or temperature corrections (e.g., a mass flowmeter) or if average barometric pressure and seasonal average temperature for the site are incorporated into the sampler calibration (see step 9.3.9). For individual pressure and temperature corrections, the ambient pressure and temperature can be obtained by onsite measurements or from a nearby weather station. Barometric pressure readings obtained from airports must be station pressure, not corrected to sea level, and may need to be corrected for differences in elevation between the sampler site and the airport. For samplers having flow recorders but not constant flow controllers, the average temperature and pressure at the site during the sampling period should be estimated from weather bureau or other available data.
8.13 Stop the sampler and carefully remove the filter, following the sampler manufacturer’s instructions. Touch only the outer edges of the filter. See the precautions in step 8.6.
8.14 Fold the filter in half lengthwise so that only surfaces with collected particulate matter are in contact and place it in the filter holder (glassine envelope or manila folder).
8.15 Record the ending time or elapsed time on the filter information record, either from the stop set-point time, from an elapsed time indicator, or from a continuous flow record. The sample period must be 1,440 ±60 min. for a valid sample.
8.16 Record on the filter information record any other factors, such as meteorological conditions, construction activity, fires or dust storms, etc., that might be pertinent to the measurement. If the sample is known to be defective, void it at this time.
8.17 Equilibrate the exposed filter in the conditioning environment for at least 24-hrs.
8.18 Immediately after equilibration, reweigh the filter to the nearest milligram and record the gross weight with the filter identification number. See Section 10 for TSP concentration calculations.
9.0 Calibration.
9.1 Calibration of the high volume sampler’s flow indicating or control device is necessary to establish traceability of the field measurement to a primary standard via a flow rate transfer standard. Figure 3a illustrates the certification of the flow rate transfer standard and Figure 3b illustrates its use in calibrating a sampler flow indicator. Determination of the corrected flow rate from the sampler flow indicator, illustrated in Figure 3c, is addressed in Section 10.1
The following calibration procedure applies to a conventional orifice-type flow transfer standard and an orifice-type flow indicator in the sampler (the most common types). For samplers using a pressure recorder having a square-root scale, 3 other acceptable calibration procedures are provided in Reference 12. Other types of transfer standards may be used if the manufacturer or user provides an appropriately modified calibration procedure that has been approved by EPA under Section 2.8 of appendix C to part 58 of this chapter.
9.2 Certification of the flow rate transfer standard.
9.2.1 Equipment required: Positive displacement standard volume meter traceable to the National Bureau of Standards (such as a Roots meter or equivalent), stop-watch, manometer, thermometer, and barometer.
9.2.2 Connect the flow rate transfer standard to the inlet of the standard volume meter. Connect the manometer to measure the pressure at the inlet of the standard volume meter. Connect the orifice manometer to the pressure tap on the transfer standard. Connect a high-volume air pump (such as a high-volume sampler blower) to the outlet side of the standard volume meter. See Figure 3a.
9.2.3 Check for leaks by temporarily clamping both manometer lines (to avoid fluid loss) and blocking the orifice with a large-diameter rubber stopper, wide cellophane tape, or other suitable means. Start the high-volume air pump and note any change in the standard volume meter reading. The reading should remain constant. If the reading changes, locate any leaks by listening for a whistling sound and/or retightening all connections, making sure that all gaskets are properly installed.
9.2.4 After satisfactorily completing the leak check as described above, unclamp both manometer lines and zero both manometers.
9.2.5 Achieve the appropriate flow rate through the system, either by means of the variable flow resistance in the transfer standard or by varying the voltage to the air pump. (Use of resistance plates as shown in Figure 1a is discouraged because the above leak check must be repeated each time a new resistance plate is installed.) At least five different but constant flow rates, evenly distributed, with at least three in the specified flow rate interval (1.1 to 1.7 m
9.2.6 Measure and record the certification data on a form similar to the one illustrated in Figure 4 according to the following steps.
9.2.7 Observe the barometric pressure and record as P
9.2.8 Read the ambient temperature in the vicinity of the standard volume meter and record it as T
9.2.9 Start the blower motor, adjust the flow, and allow the system to run for at least 1 min for a constant motor speed to be attained.
9.2.10 Observe the standard volume meter reading and simultaneously start a stopwatch. Record the initial meter reading (V
9.2.11 Maintain this constant flow rate until at least 3 m
9.2.12 After at least 3 m
9.2.13 Calculate the volume measured by the standard volume meter at meter conditions of temperature and pressures as V
9.2.14 Correct this volume to standard volume (std m
Record Q
9.2.15 Repeat steps 9.2.9 through 9.2.14 for at least four additional constant flow rates, evenly spaced over the approximate range of 1.0 to 1.8 std m
9.2.16 For each flow, compute
9.2.17 Recalibrate the transfer standard annually or as required by applicable quality control procedures. (See Reference 2.)
9.3 Calibration of sampler flow indicator.
For samplers equipped with a flow controlling device, the flow controller must be disabled to allow flow changes during calibration of the sampler’s flow indicator, or the alternate calibration of the flow controller given in 9.4 may be used. For samplers using an orifice-type flow indicator downstream of the motor, do not vary the flow rate by adjusting the voltage or power supplied to the sampler.
9.3.1 A form similar to the one illustrated in Figure 5 should be used to record the calibration data.
9.3.2 Connect the transfer standard to the inlet of the sampler. Connect the orifice manometer to the orifice pressure tap, as illustrated in Figure 3b. Make sure there are no leaks between the orifice unit and the sampler.
9.3.3 Operate the sampler for at least 5 minutes to establish thermal equilibrium prior to the calibration.
9.3.4 Measure and record the ambient temperature, T
9.3.5 Adjust the variable resistance or, if applicable, insert the appropriate resistance plate (or no plate) to achieve the desired flow rate.
9.3.6 Let the sampler run for at least 2 min to re-establish the run-temperature conditions. Read and record the pressure drop across the orifice (ΔH) and the sampler flow rate indication (I) in the appropriate columns of Figure 5.
9.3.7 Calculate √ΔΔH(P
9.3.8 Repeat steps 9.3.5, 9.3.6, and 9.3.7 for several additional flow rates distributed over a range that includes 1.1 to 1.7 std m
9.3.9 Determine the calibration curve by plotting values of the appropriate expression involving I, selected from table 1, against Q
9.3.10 Draw the sampler calibration curve or calculate the linear least squares slope (m), intercept (b), and correlation coefficient of the calibration curve: [Expression from table 1]= mQ
9.3.11 For a sampler equipped with a flow controller, the flow controlling mechanism should be re-enabled and set to a flow near the lower flow limit to allow maximum control range. The sample flow rate should be verified at this time with a clean filter installed. Then add two or more filters to the sampler to see if the flow controller maintains a constant flow; this is particularly important at high altitudes where the range of the flow controller may be reduced.
9.4 Alternate calibration of flow-controlled samplers. A flow-controlled sampler may be calibrated solely at its controlled flow rate, provided that previous operating history of the sampler demonstrates that the flow rate is stable and reliable. In this case, the flow indicator may remain uncalibrated but should be used to indicate any relative change between initial and final flows, and the sampler should be recalibrated more often to minimize potential loss of samples because of controller malfunction.
9.4.1 Set the flow controller for a flow near the lower limit of the flow range to allow maximum control range.
9.4.2 Install a clean filter in the sampler and carry out steps 9.3.2, 9.3.3, 9.3.4, 9.3.6, and 9.3.7.
9.4.3 Following calibration, add one or two additional clean filters to the sampler, reconnect the transfer standard, and operate the sampler to verify that the controller maintains the same calibrated flow rate; this is particularly important at high altitudes where the flow control range may be reduced.


10.0 Calculations of TSP Concentration.
10.1 Determine the average sampler flow rate during the sampling period according to either 10.1.1 or 10.1.2 below.
10.1.1 For a sampler without a continuous flow recorder, determine the appropriate expression to be used from table 2 corresponding to the one from table 1 used in step 9.3.9. Using this appropriate expression, determine Q
10.1.2 For a sampler with a continuous flow recorder, determine the average flow rate device reading, I, for the period. Determine the appropriate expression from table 2 corresponding to the one from table 1 used in step 9.3.9. Then using this expression and the average flow rate reading, determine Q
If the trace shows substantial flow change during the sampling period, greater accuracy may be achieved by dividing the sampling period into intervals and calculating an average reading before determining Q
10.2 Calculate the total air volume sampled as:
10.3 Calculate and report the particulate matter concentration as:
10.4 If desired, the actual particulate matter concentration (see Section 2.2) can be calculated as follows:
11.0 References.
1. Quality Assurance Handbook for Air Pollution Measurement Systems, Volume I, Principles. EPA–600/9–76–005, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, 1976.
2. Quality Assurance Handbook for Air Pollution Measurement Systems, Volume II, Ambient Air Specific Methods. EPA–600/4–77–027a, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, 1977.
3. Wedding, J. B., A. R. McFarland, and J. E. Cernak. Large Particle Collection Characteristics of Ambient Aerosol Samplers. Environ. Sci. Technol. 11:387–390, 1977.
4. McKee, H. C., et al. Collaborative Testing of Methods to Measure Air Pollutants, I. The High-Volume Method for Suspended Particulate Matter. J. Air Poll. Cont. Assoc., 22 (342), 1972.
5. Clement, R. E., and F. W. Karasek. Sample Composition Changes in Sampling and Analysis of Organic Compounds in Aerosols. The Intern. J. Environ. Anal. Chem., 7:109, 1979.
6. Lee, R. E., Jr., and J. Wagman. A Sampling Anomaly in the Determination of Atmospheric Sulfuric Concentration. Am. Ind. Hygiene Assoc. J., 27:266, 1966.
7. Appel, B. R., et al. Interference Effects in Sampling Particulate Nitrate in Ambient Air. Atmospheric Environment, 13:319, 1979.
8. Tierney, G. P., and W. D. Conner. Hygroscopic Effects on Weight Determinations of Particulates Collected on Glass-Fiber Filters. Am. Ind. Hygiene Assoc. J., 28:363, 1967.
9. Chahal, H. S., and D. J. Romano. High-Volume Sampling Effect of Windborne Particulate Matter Deposited During Idle Periods. J. Air Poll. Cont. Assoc., Vol. 26 (885), 1976.
10. Patterson, R. K. Aerosol Contamination from High-Volume Sampler Exhaust. J. Air Poll. Cont. Assoc., Vol. 30 (169), 1980.
11. EPA Test Procedures for Determining pH and Integrity of High-Volume Air Filters. QAD/M–80.01. Available from the Methods Standardization Branch, Quality Assurance Division, Environmental Monitoring Systems Laboratory (MD–77), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, 1980.
12. Smith, F., P. S. Wohlschlegel, R. S. C. Rogers, and D. J. Mulligan. Investigation of Flow Rate Calibration Procedures Associated with the High-Volume Method for Determination of Suspended Particulates. EPA–600/4–78–047, U.S. Environmental Protection Agency, Research Triangle Park, NC, June 1978.





Appendix C to Part 50—Measurement Principle and Calibration Procedure for the Measurement of Carbon Monoxide in the Atmosphere (Non-Dispersive Infrared Photometry)
1.1 This non-dispersive infrared photometry (NDIR) Federal Reference Method (FRM) provides measurements of the concentration of carbon monoxide (CO) in ambient air for determining compliance with the primary and secondary National Ambient Air Quality Standards (NAAQS) for CO as specified in § 50.8 of this chapter. The method is applicable to continuous sampling and measurement of ambient CO concentrations suitable for determining 1-hour or longer average measurements. The method may also provide measurements of shorter averaging times, subject to specific analyzer performance limitations. Additional CO monitoring quality assurance procedures and guidance are provided in part 58, appendix A, of this chapter and in reference 1 of this appendix C.
2.1 Measurements of CO in ambient air are based on automated measurement of the absorption of infrared radiation by CO in an ambient air sample drawn into an analyzer employing non-wavelength-dispersive, infrared photometry (NDIR method). Infrared energy from a source in the photometer is passed through a cell containing the air sample to be analyzed, and the quantitative absorption of energy by CO in the sample cell is measured by a suitable detector. The photometer is sensitized specifically to CO by employing CO gas in a filter cell in the optical path, which, when compared to a differential optical path without a CO filter cell, limits the measured absorption to one or more of the characteristic wavelengths at which CO strongly absorbs. However, to meet measurement performance requirements, various optical filters, reference cells, rotating gas filter cells, dual-beam configurations, moisture traps, or other means may also be used to further enhance sensitivity and stability of the photometer and to minimize potential measurement interference from water vapor, carbon dioxide (CO
2.2 The measurement system is calibrated by referencing the analyzer’s CO measurements to CO concentration standards traceable to a National Institute of Standards and Technology (NIST) primary standard for CO, as described in the associated calibration procedure specified in section 4 of this reference method.
2.3 An analyzer implementing this measurement principle will be considered a reference method only if it has been designated as a reference method in accordance with part 53 of this chapter.
2.4 Sampling considerations. The use of a particle filter in the sample inlet line of a CO FRM analyzer is optional and left to the discretion of the user unless such a filter is specified or recommended by the analyzer manufacturer in the analyzer’s associated operation or instruction manual.
3.1 The NDIR measurement principle is potentially susceptible to interference from water vapor and CO
4.1 Principle. Either of two methods may be selected for dynamic multipoint calibration of FRM CO analyzers, using test gases of accurately known CO concentrations obtained from one or more compressed gas cylinders certified as CO transfer standards:
4.1.1 Dilution method: A single certified standard cylinder of CO is quantitatively diluted as necessary with zero air to obtain the various calibration concentration standards needed.
4.1.2 Multiple-cylinder method: Multiple, individually certified standard cylinders of CO are used for each of the various calibration concentration standards needed.
4.1.3 Additional information on calibration may be found in Section 12 of reference 1.
4.2 Apparatus. The major components and typical configurations of the calibration systems for the two calibration methods are shown in Figures 1 and 2. Either system may be made up using common laboratory components, or it may be a commercially manufactured system. In either case, the principal components are as follows:
4.2.1 CO standard gas flow control and measurement devices (or a combined device) capable of regulating and maintaining the standard gas flow rate constant to within ±2 percent and measuring the gas flow rate accurate to within ±2 percent, properly calibrated to a NIST-traceable standard.
4.2.2 For the dilution method (Figure 1), dilution air flow control and measurement devices (or a combined device) capable of regulating and maintaining the air flow rate constant to within ±2 percent and measuring the air flow rate accurate to within ±2 percent, properly calibrated to a NIST-traceable standard.
4.2.3 Standard gas pressure regulator(s) for the standard CO cylinder(s), suitable for use with a high-pressure CO gas cylinder and having a non-reactive diaphragm and internal parts and a suitable delivery pressure.
4.2.4 Mixing chamber for the dilution method of an inert material and of proper design to provide thorough mixing of CO standard gas and diluent air streams.
4.2.5 Output sampling manifold, constructed of an inert material and of sufficient diameter to ensure an insignificant pressure drop at the analyzer connection. The system must have a vent designed to ensure nearly atmospheric pressure at the analyzer connection port and to prevent ambient air from entering the manifold.
4.3.1 CO gas concentration transfer standard(s) of CO in air, containing an appropriate concentration of CO suitable for the selected operating range of the analyzer under calibration and traceable to a NIST standard reference material (SRM). If the CO analyzer has significant sensitivity to CO
4.3.2 For the dilution method, clean zero air, free of contaminants that could cause a detectable response on or a change in sensitivity of the CO analyzer. The zero air should contain
4.4.1 Assemble or obtain a suitable dynamic dilution calibration system such as the one shown schematically in Figure 1. Generally, all calibration gases including zero air must be introduced into the sample inlet of the analyzer. However, if the analyzer has special, approved zero and span inlets and automatic valves to specifically allow introduction of calibration standards at near atmospheric pressure, such inlets may be used for calibration in lieu of the sample inlet. For specific operating instructions, refer to the manufacturer’s manual.
4.4.2 Ensure that there are no leaks in the calibration system and that all flowmeters are properly and accurately calibrated, under the conditions of use, if appropriate, against a reliable volume or flow rate standard such as a soap-bubble meter or wet-test meter traceable to a NIST standard. All volumetric flow rates should be corrected to the same temperature and pressure such as 298.15 K (25 °C) and 760 mm Hg (101 kPa), using a correction formula such as the following:

4.4.3 Select the operating range of the CO analyzer to be calibrated. Connect the measurement signal output of the analyzer to an appropriate readout instrument to allow the analyzer’s measurement output to be continuously monitored during the calibration. Where possible, this readout instrument should be the same one used to record routine monitoring data, or, at least, an instrument that is as closely representative of that system as feasible.
4.4.4 Connect the inlet of the CO analyzer to the output-sampling manifold of the calibration system.
4.4.5 Adjust the calibration system to deliver zero air to the output manifold. The total air flow must exceed the total demand of the analyzer(s) connected to the output manifold to ensure that no ambient air is pulled into the manifold vent. Allow the analyzer to sample zero air until a stable response is obtained. After the response has stabilized, adjust the analyzer zero reading.
4.4.6 Adjust the zero air flow rate and the CO gas flow rate from the standard CO cylinder to provide a diluted CO concentration of approximately 80 percent of the measurement upper range limit (URL) of the operating range of the analyzer. The total air flow rate must exceed the total demand of the analyzer(s) connected to the output manifold to ensure that no ambient air is pulled into the manifold vent. The exact CO concentration is calculated from:

4.4.7 Generate several additional concentrations (at least three evenly spaced points across the remaining scale are suggested to verify linearity) by decreasing F
4.5 Procedure Using the Multiple-Cylinder Method. Use the procedure for the dilution method with the following changes:
4.5.1 Use a multi-cylinder, dynamic calibration system such as the typical one shown in Figure 2.
4.5.2 The flowmeter need not be accurately calibrated, provided the flow in the output manifold can be verified to exceed the analyzer’s flow demand.
4.5.3 The various CO calibration concentrations required in Steps 4.4.5, 4.4.6, and 4.4.7 are obtained without dilution by selecting zero air or the appropriate certified standard cylinder.
4.6 Frequency of Calibration. The frequency of calibration, as well as the number of points necessary to establish the calibration curve and the frequency of other performance checking, will vary by analyzer. However, the minimum frequency, acceptance criteria, and subsequent actions are specified in reference 1, appendix D, “Measurement Quality Objectives and Validation Template for CO” (page 5 of 30). The user’s quality control program should provide guidelines for initial establishment of these variables and for subsequent alteration as operational experience is accumulated. Manufacturers of CO analyzers should include in their instruction/operation manuals information and guidance as to these variables and on other matters of operation, calibration, routine maintenance, and quality control.
1. QA Handbook for Air Pollution Measurement Systems—Volume II. Ambient Air Quality Monitoring Program. U.S. EPA. EPA–454/B–08–003 (2008).


Appendix D to Part 50—Reference Measurement Principle and Calibration Procedure for the Measurement of Ozone in the Atmosphere (Chemiluminescence Method)
1.0 Applicability.
1.1 This chemiluminescence method provides reference measurements of the concentration of ozone (O
2.0 Measurement Principle.
2.1 This reference method is based on continuous automated measurement of the intensity of the characteristic chemiluminescence released by the gas phase reaction of O
2.2 The measurement system is calibrated by referencing the instrumental chemiluminescence measurements to certified O
2.3 An analyzer implementing this measurement principle is shown schematically in Figure 1. Designs implementing this measurement principle must include: an appropriately designed mixing and measurement cell; a suitable quantitative photometric measurement system with adequate sensitivity and wavelength specificity for O
2.4 An analyzer implementing this measurement principle and calibration procedure will be considered a federal reference method (FRM) only if it has been designated as a reference method in accordance with part 53 of this chapter.
2.5 Sampling considerations. The use of a particle filter on the sample inlet line of a chemiluminescence O
3.0 Interferences.
3.1 Except as described in 3.2 below, the chemiluminescence measurement system is inherently free of significant interferences from other pollutant substances that may be present in ambient air.
3.2 A small sensitivity to variations in the humidity of the sample air is minimized by a sample air dryer. Potential loss of O
4.0 Calibration Procedure.
4.1 Principle. The calibration procedure is based on the photometric assay of O

A stable O

The calculated O
4.2 Applicability. This procedure is applicable to the calibration of ambient air O
4.3 Apparatus. A complete UV calibration system consists of an O
4.3.1 UV photometer. The photometer consists of a low-pressure mercury discharge lamp, (optional) collimation optics, an absorption cell, a detector, and signal-processing electronics, as illustrated in Figure 2. It must be capable of measuring the transmittance, I/I
4.3.2 Air flow controllers. Air flow controllers are devices capable of regulating air flows as necessary to meet the output stability and photometer precision requirements.
4.3.3 Ozone generator. The ozone generator used must be capable of generating stable levels of O
4.3.4 Output manifold. The output manifold must be constructed of glass, Teflon, or other relatively inert material, and should be of sufficient diameter to insure a negligible pressure drop at the photometer connection and other output ports. The system must have a vent designed to insure atmospheric pressure in the manifold and to prevent ambient air from entering the manifold.
4.3.5 Two-way valve. A manual or automatic two-way valve, or other means is used to switch the photometer flow between zero air and the O
4.3.6 Temperature indicator. A device to indicate temperature must be used that is accurate to ±1 °C.
4.3.7 Barometer or pressure indicator. A device to indicate barometric pressure must be used that is accurate to ±2 torr.
4.4 Reagents.
4.4.1 Zero air. The zero air must be free of contaminants which would cause a detectable response from the O
4.5 Procedure.
4.5.1 General operation. The calibration photometer must be dedicated exclusively to use as a calibration standard. It must always be used with clean, filtered calibration gases, and never used for ambient air sampling. A number of advantages are realized by locating the calibration photometer in a clean laboratory where it can be stationary, protected from the physical shock of transportation, operated by a responsible analyst, and used as a common standard for all field calibrations via transfer standards.
4.5.2 Preparation. Proper operation of the photometer is of critical importance to the accuracy of this procedure. Upon initial operation of the photometer, the following steps must be carried out with all quantitative results or indications recorded in a chronological record, either in tabular form or plotted on a graphical chart. As the performance and stability record of the photometer is established, the frequency of these steps may be reduced to be consistent with the documented stability of the photometer and the guidance provided in Reference 12.
4.5.2.1 Instruction manual. Carry out all set up and adjustment procedures or checks as described in the operation or instruction manual associated with the photometer.
4.5.2.2 System check. Check the photometer system for integrity, leaks, cleanliness, proper flow rates, etc. Service or replace filters and zero air scrubbers or other consumable materials, as necessary.
4.5.2.3 Linearity. Verify that the photometer manufacturer has adequately established that the linearity error of the photometer is less than 3%, or test the linearity by dilution as follows: Generate and assay an O

The linearity error must be less than 5%. Since the accuracy of the measured flow-rates will affect the linearity error as measured this way, the test is not necessarily conclusive. Additional information on verifying linearity is contained in Reference 13.
4.5.2.4 Inter-comparison. The photometer must be inter-compared annually, either directly or via transfer standards, with a NIST standard reference photometer (SRP) or calibration photometers used by other agencies or laboratories.
4.5.2.5 Ozone losses. Some portion of the O
4.5.3 Assay of O
4.5.3.1 Allow the photometer system to warm up and stabilize.
4.5.3.2 Verify that the flow rate through the photometer absorption cell, F, allows the cell to be flushed in a reasonably short period of time (2 liter/min is a typical flow). The precision of the measurements is inversely related to the time required for flushing, since the photometer drift error increases with time.
4.5.3.3 Ensure that the flow rate into the output manifold is at least 1 liter/min greater than the total flow rate required by the photometer and any other flow demand connected to the manifold.
4.5.3.4 Ensure that the flow rate of zero air, Fz, is at least 1 liter/min greater than the flow rate required by the photometer.
4.5.3.5 With zero air flowing in the output manifold, actuate the two-way valve to allow the photometer to sample first the manifold zero air, then Fz. The two photometer readings must be equal (I = I
In some commercially available photometers, the operation of the two-way valve and various other operations in section 4.5.3 may be carried out automatically by the photometer.
4.5.3.6 Adjust the O
4.5.3.7 Actuate the two-way valve to allow the photometer to sample zero air until the absorption cell is thoroughly flushed and record the stable measured value of Io.
4.5.3.8 Actuate the two-way valve to allow the photometer to sample the O
4.5.3.9 Record the temperature and pressure of the sample in the photometer absorption cell. (See Reference 13 for guidance.)
4.5.3.10. Calculate the O

Some commercial photometers may automatically evaluate all or part of equation 4. It is the operator’s responsibility to verify that all of the information required for equation 4 is obtained, either automatically by the photometer or manually. For “automatic” photometers which evaluate the first term of equation 4 based on a linear approximation, a manual correction may be required, particularly at higher O3 levels. See the photometer instruction manual and Reference 13 for guidance.
4.5.3.11 Obtain additional O
4.5.4 Certification of transfer standards. A transfer standard is certified by relating the output of the transfer standard to one or more O
4.5.5 Calibration of ozone analyzers. Ozone analyzers must be calibrated as follows, using O
4.5.5.1 Allow sufficient time for the O
4.5.5.2 Allow the O
4.5.5.3 Generate an O
4.5.5.4 Adjust the O
4.5.5.5 Generate additional O
4.5.5.6 Plot the O
4.5.5.7 Option 1: The various O

Additional information on calibration and pollutant standards is provided in Section 12 of Reference 14.
5.0 Frequency of Calibration.
5.1 The frequency of calibration, as well as the number of points necessary to establish the calibration curve, and the frequency of other performance checking will vary by analyzer; however, the minimum frequency, acceptance criteria, and subsequent actions are specified in Appendix D of Reference 14: Measurement Quality Objectives and Validation Templates. The user’s quality control program shall provide guidelines for initial establishment of these variables and for subsequent alteration as operational experience is accumulated. Manufacturers of analyzers should include in their instruction/operation manuals information and guidance as to these variables and on other matters of operation, calibration, routine maintenance, and quality control.
6.0 References.
EPA–454/B–17–001, January 2017.



Appendix E to Part 50 [Reserved]
Appendix F to Part 50—Measurement Principle and Calibration Procedure for the Measurement of Nitrogen Dioxide in the Atmosphere (Gas Phase Chemiluminescence)
1. Atmospheric concentrations of nitrogen dioxide (NO
2. Sampling considerations.
2.1 Chemiluminescence NO/NO
2.2 The use of integrating flasks on the sample inlet line of chemiluminescence NO/NO
2.3 The use of particulate filters on the sample inlet line of chemiluminescence NO/NO
3. An analyzer based on this principle will be considered a reference method only if it has been designated as a reference method in accordance with part 53 of this chapter.
1. Alternative A—Gas phase titration (GPT) of an NO standard with O
Major equipment required: Stable O
1.1 Principle. This calibration technique is based upon the rapid gas phase reaction between NO and O
1.2 Apparatus. Figure 1, a schematic of a typical GPT apparatus, shows the suggested configuration of the components listed below. All connections between components in the calibration system downstream from the O
1.2.1 Air flow controllers. Devices capable of maintaining constant air flows within ±2% of the required flowrate.
1.2.2 NO flow controller. A device capable of maintaining constant NO flows within ±2% of the required flowrate. Component parts in contact with the NO should be of a non-reactive material.
1.2.3 Air flowmeters. Calibrated flowmeters capable of measuring and monitoring air flowrates with an accuracy of ±2% of the measured flowrate.
1.2.4 NO flowmeter. A calibrated flowmeter capable of measuring and monitoring NO flowrates with an accuracy of ±2% of the measured flowrate. (Rotameters have been reported to operate unreliably when measuring low NO flows and are not recommended.)
1.2.5 Pressure regulator for standard NO cylinder. This regulator must have a nonreactive diaphragm and internal parts and a suitable delivery pressure.
1.2.6 Ozone generator. The generator must be capable of generating sufficient and stable levels of O
1.2.7 Valve. A valve may be used as shown in Figure 1 to divert the NO flow when zero air is required at the manifold. The valve should be constructed of glass, Teflon ®, or other nonreactive material.
1.2.8 Reaction chamber. A chamber, constructed of glass, Teflon ®, or other nonreactive material, for the quantitative reaction of O
1.2.9 Mixing chamber. A chamber constructed of glass, Teflon ®, or other nonreactive material and designed to provide thorough mixing of reaction products and diluent air. The residence time is not critical when the dynamic parameter specification given in 1.4 is met.
1.2.10 Output manifold. The output manifold should be constructed of glass, Teflon ®, or other non-reactive material and should be of sufficient diameter to insure an insignificant pressure drop at the analyzer connection. The system must have a vent designed to insure atmospheric pressure at the manifold and to prevent ambient air from entering the manifold.
1.3 Reagents.
1.3.1 NO concentration standard. Gas cylinder standard containing 50 to 100 ppm NO in N
1.3.2 Zero air. Air, free of contaminants which will cause a detectable response on the NO/NO
1.4 Dynamic parameter specification.
1.4.1 The O
1.4.2 The flow conditions to be used in the GPT system are determined by the following procedure:
(a) Determine F
(b) Establish [NO]
(c) Determine F
(d) Select a convenient or available reaction chamber volume. Initially, a trial V
(e) Compute FO as
(f) Compute t
(g) Compute the diluent air flowrate as
(h) If F
A dynamic parameter lower than 2.75 ppm-minutes may be used if it can be determined empirically that quantitative reaction of O
1.5 Procedure.
1.5.1 Assemble a dynamic calibration system such as the one shown in Figure 1.
1.5.2 Insure that all flowmeters are calibrated under the conditions of use against a reliable standard such as a soap-bubble meter or wet-test meter. All volumetric flowrates should be corrected to 25 °C and 760 mm Hg. A discussion on the calibration of flowmeters is given in reference 13.
1.5.3 Precautions must be taken to remove O
1.5.4 Select the operating range of the NO/NO
Some analyzer designs may require identical ranges for NO, NO
1.5.5 Connect the recorder output cable(s) of the NO/NO
1.5.6 Determine the GPT flow conditions required to meet the dynamic parameter specification as indicated in 1.4.
1.5.7 Adjust the diluent air and O
Some analyzers may have separate zero controls for NO, NO
Offsetting the analyzer zero adjustments to + 5 percent of scale is recommended to facilitate observing negative zero drift. Record the stable zero air responses as Z
1.5.8 Preparation of NO and NO
1.5.8.1 Adjustment of NO span control. Adjust the NO flow from the standard NO cylinder to generate an NO concentration of approximately 80 percent of the upper range limit (URL) of the NO range. This exact NO concentration is calculated from:
Some analyzers may have separate span controls for NO, NO
1.5.8.2 Adjustment of NO
If the analyzer has only one span control, the span adjustment is made on the NO channel and no further adjustment is made here for NO
1.5.8.3 Generate several additional concentrations (at least five evenly spaced points across the remaining scale are suggested to verify linearity) by decreasing F
1.5.9 Preparation of NO
1.5.9.1 Assuming the NO
1.5.9.2 Adjust the O
1.5.9.3 Calculate the resulting NO
If the analyzer has only one or two span controls, the span adjustments are made on the NO channel or NO and NO
1.5.9.4 Maintaining the same F
1.5.10 Determination of converter efficiency.
1.5.10.1 For each NO
Supplemental information on calibration and other procedures in this method are given in reference 13.
2. Alternative B—NO
Major equipment required:
Stable O
Chemiluminescence NO/NO
NO concentration standard.
NO
2.1 Principle. Atmospheres containing accurately known concentrations of nitrogen dioxide are generated by means of a permeation device. (10) The permeation device emits NO
2.2 Apparatus. A typical system suitable for generating the required NO and NO
2.2.1 Air flow controllers. Devices capable of maintaining constant air flows within ±2% of the required flowrate.
2.2.2 NO flow controller. A device capable of maintaining constant NO flows within ±2% of the required flowrate. Component parts in contact with the NO must be of a non-reactive material.
2.2.3 Air flowmeters. Calibrated flowmeters capable of measuring and monitoring air flowrates with an accuracy of ±2% of the measured flowrate.
2.2.4 NO flowmeter. A calibrated flowmeter capable of measuring and monitoring NO flowrates with an accuracy of ±2% of the measured flowrate. (Rotameters have been reported to operate unreliably when measuring low NO flows and are not recommended.)
2.2.5 Pressure regulator for standard NO cylinder. This regulator must have a non-reactive diaphragm and internal parts and a suitable delivery pressure.
2.2.6 Drier. Scrubber to remove moisture from the permeation device air system. The use of the drier is optional with NO
2.2.7 Constant temperature chamber. Chamber capable of housing the NO
2.2.8 Temperature measuring device. Device capable of measuring and monitoring the temperature of the NO
2.2.9 Valves. A valve may be used as shown in Figure 2 to divert the NO
The valves should be constructed of glass, Teflon ®, or other nonreactive material.
2.2.10 Mixing chamber. A chamber constructed of glass, Teflon ®, or other nonreactive material and designed to provide thorough mixing of pollutant gas streams and diluent air.
2.2.11 Output manifold. The output manifold should be constructed of glass, Teflon ®, or other non-reactive material and should be of sufficient diameter to insure an insignificant pressure drop at the analyzer connection. The system must have a vent designed to insure atmospheric pressure at the manifold and to prevent ambient air from entering the manifold.
2.3 Reagents.
2.3.1 Calibration standards. Calibration standards are required for both NO and NO
2.3.1.1 NO
2.3.1.2 NO Concentration standard. Gas cylinder containing 50 to 100 ppm NO in N
2.3.3 Zero air. Air, free of contaminants which might react with NO or NO
2.4 Procedure.
2.4.1 Assemble the calibration apparatus such as the typical one shown in Figure 2.
2.4.2 Insure that all flowmeters are calibrated under the conditions of use against a reliable standard such as a soap bubble meter or wet-test meter. All volumetric flowrates should be corrected to 25 °C and 760 mm Hg. A discussion on the calibration of flowmeters is given in reference 13.
2.4.3 Install the permeation device in the constant temperature chamber. Provide a small fixed air flow (200–400 scm
2.4.4 Precautions must be taken to remove O
(1) Carefully evacuating the regulator, when possible, after the regulator has been connected to the cylinder and before opening the cylinder valve;
(2) Thoroughly flushing the regulator and delivery system with NO after opening the cylinder valve;
(3) Not removing the regulator from the cylinder between calibrations unless absolutely necessary. Further discussion of these procedures is given in reference 13.
2.4.5 Select the operating range of the NO/NO
Some analyzer designs may require identical ranges for NO, NO
2.4.6 Connect the recorder output cable(s) of the NO/NO
2.4.7 Switch the valve to vent the flow from the permeation device and adjust the diluent air flowrate, F
Some analyzers may have separate zero controls for NO, NO
2.4.8 Preparation of NO and NO
2.4.8.1 Adjustment of NO span control. Adjust the NO flow from the standard NO cylinder to generate an NO concentration of approximately 80% of the upper range limit (URL) of the NO range. The exact NO concentration is calculated from:
Some analyzers may have separate span controls for NO, NO
2.4.8.2 Adjustment of NO
If the analyzer has only one span control, the span adjustment is made on the NO channel and no further adjustment is made here for NO
2.4.8.3 Generate several additional concentrations (at least five evenly spaced points across the remaining scale are suggested to verify linearity) by decreasing F
2.4.9 Preparation of NO
2.4.9.1 Remove the NO flow. Assuming the NO
2.4.9.2 Adjust F
If the analyzer has only one or two span controls, the span adjustments are made on the NO channel or NO and NO
2.4.9.3 Adjust F
2.4.10 Determination of converter efficiency.
2.4.10.1 Plot [NO
Supplemental information on calibration and other procedures in this method are given in reference 13.
3. Frequency of calibration. The frequency of calibration, as well as the number of points necessary to establish the calibration curve and the frequency of other performance checks, will vary from one analyzer to another. The user’s quality control program should provide guidelines for initial establishment of these variables and for subsequent alteration as operational experience is accumulated. Manufacturers of analyzers should include in their instruction/operation manuals information and guidance as to these variables and on other matters of operation, calibration, and quality control.
1. A. Fontijn, A. J. Sabadell, and R. J. Ronco, “Homogeneous Chemiluminescent Measurement of Nitric Oxide with Ozone,” Anal. Chem., 42, 575 (1970).
2. D. H. Stedman, E. E. Daby, F. Stuhl, and H. Niki, “Analysis of Ozone and Nitric Oxide by a Chemiluminiscent Method in Laboratory and Atmospheric Studies of Photochemical Smog,” J. Air Poll. Control Assoc., 22, 260 (1972).
3. B. E. Martin, J. A. Hodgeson, and R. K. Stevens, “Detection of Nitric Oxide Chemiluminescence at Atmospheric Pressure,” Presented at 164th National ACS Meeting, New York City, August 1972.
4. J. A. Hodgeson, K. A. Rehme, B. E. Martin, and R. K. Stevens, “Measurements for Atmospheric Oxides of Nitrogen and Ammonia by Chemiluminescence,” Presented at 1972 APCA Meeting, Miami, FL, June 1972.
5. R. K. Stevens and J. A. Hodgeson, “Applications of Chemiluminescence Reactions to the Measurement of Air Pollutants,” Anal. Chem., 45, 443A (1973).
6. L. P. Breitenbach and M. Shelef, “Development of a Method for the Analysis of NO
7. A. M. Winer, J. W. Peters, J. P. Smith, and J. N. Pitts, Jr., “Response of Commercial Chemiluminescent NO-NO
8. K. A. Rehme, B. E. Martin, and J. A. Hodgeson, Tentative Method for the Calibration of Nitric Oxide, Nitrogen Dioxide, and Ozone Analyzers by Gas Phase Titration,” EPA-R2-73-246, March 1974.
9. J. A. Hodgeson, R. K. Stevens, and B. E. Martin, “A Stable Ozone Source Applicable as a Secondary Standard for Calibration of Atmospheric Monitors,” ISA Transactions, 11, 161 (1972).
10. A. E. O’Keeffe and G. C. Ortman, “Primary Standards for Trace Gas Analysis,” Anal. Chem., 38, 760 (1966).
11. F. P. Scaringelli, A. E. O’Keeffe, E. Rosenberg, and J. P. Bell, “Preparation of Known Concentrations of Gases and Vapors with Permeation Devices Calibrated Gravimetrically,” Anal. Chem., 42, 871 (1970).
12. H. L. Rook, E. E. Hughes, R. S. Fuerst, and J. H. Margeson, “Operation Characteristics of NO
13. E. C. Ellis, “Technical Assistance Document for the Chemiluminescence Measurement of Nitrogen Dioxide,” EPA-E600/4-75-003 (Available in draft form from the United States Environmental Protection Agency, Department E (MD–76), Environmental Monitoring and Support Laboratory, Research Triangle Park, NC 27711).
14. A Procedure for Establishing Traceability of Gas Mixtures to Certain National Bureau of Standards Standard Reference Materials. EPA–600/7–81–010, Joint publication by NBS and EPA. Available from the U.S. Environmental Protection Agency, Environmental Monitoring Systems Laboratory (MD–77), Research Triangle Park, NC 27711, May 1981.
15. Quality Assurance Handbook for Air Pollution Measurement Systems, Volume II, Ambient Air Specific Methods. The U.S. Environmental Protection Agency, Environmental Monitoring Systems Laboratory, Research Triangle Park, NC 27711. Publication No. EAP–600/4–77–027a.


Appendix G to Part 50—Reference Method for the Determination of Lead in Total Suspended Particulate Matter
Based on review of the air quality criteria and national ambient air quality standard (NAAQS) for lead (Pb) completed in 2008, the EPA made revisions to the primary and secondary NAAQS for Pb to protect public health and welfare. The EPA revised the level from 1.5 µg/m
Pb-TSP is collected for 24 hours on a TSP filter as described in Appendix B of part 50, the Reference Method for the Determination of Suspended Particulate Matter in the Atmosphere (High-Volume Method). This method is for the analysis of Pb from TSP filters by Inductively Coupled Plasma Mass Spectrometry (ICP–MS) using a heated ultrasonic bath with nitric acid (HNO
This method is based on the EPA’s Office of Solid Waste (SW–846) Method 6020A—Inductively Coupled Plasma Mass Spectrometry (U.S. EPA, 2007). Wording in certain sections of this method is paraphrased or taken directly from Method 6020A.
1.1 ICP–MS is applicable for the sub-µg/mL (ppb) determination of Pb in a wide variety of matrices. Results reported for monitoring or compliance purposes are calculated in µg/m
1.2 Due to variations in the isotopic abundance of Pb, the value for total Pb must be based on the sum of the signal intensities for isotopic masses, 206, 207, and 208. Most instrument software packages are able to sum the primary isotope signal intensities automatically.
1.3 ICP–MS requires the use of an internal standard.
1.4 Use of this method is restricted to use by, or under supervision of, properly trained and experienced laboratory personnel. Requirements include training and experience in inorganic sample preparation, including acid extraction, and also knowledge in the recognition and in the correction of spectral, chemical and physical interference in ICP–MS.
2.1 This method describes the acid extraction of Pb in particulate matter collected on glass fiber, quartz, or PTFE ambient air filters with subsequent measurement of Pb by ICP–MS. Estimates of the Method Detection Limit (MDL) or sensitivity of the method are provided in Tables 1, 3 and 5 and determined using Pb-spiked filters or filter strips analyzed in accordance with the guidance provided in 40 CFR 136, Appendix B—Determination and procedures for the Determination of the Method Detection Limit—Revision 1.1. The analytical range of the method is 0.00024 µg/m
2.2 This method includes two extraction methods. In the first method, a solution of HNO
2.3 Calibration standards and check standards are prepared to matrix match the acid composition of the samples. ICP–MS analysis is then performed. With this method, the samples are first aspirated and the aerosol thus created is transported by a flow of argon gas into the plasma torch. The ions produced (e.g., Pb
4.1 Reagents, glassware, plasticware, and other sample processing hardware may yield artifacts and/or interferences to sample analysis. If reagent blanks, filter blanks, or quality control blanks yield results above the detection limit, the source of contamination must be identified. All containers and reagents used in the processing of the samples must be checked for contamination prior to sample extraction and analysis. Reagents shall be diluted to match the final concentration of the extracts and analyzed for Pb. Labware shall be rinsed with dilute acid solution and the solution analyzed. Once a reagent or labware article (such as extraction tubes) from a manufacturer has been successfully screened, additional screening is not required unless contamination is suspected.
4.2 Isobaric elemental interferences in ICP–MS are caused by isotopes of different elements forming atomic ions with the same nominal mass-to-charge ratio (m/z) as the species of interest. There are no species found in ambient air that will result in isobaric interference with the three Pb isotopes (206, 207, and 208) being measured. Polyatomic interferences occur when two or more elements combine to form an ion with the same mass-to-charge ratio as the isotope being measured. Pb is not subject to interference from common polyatomic ions and no correction is required.
4.3 The distribution of Pb isotopes is not constant. The analysis of total Pb should be based on the summation of signal intensities for the isotopic masses 206, 207, and 208. In most cases, the instrument software can perform the summation automatically.
4.4 Physical interferences are associated with the sample nebulization and transport processes as well as with ion-transmission efficiencies. Dissolved solids can deposit on the nebulizer tip of a pneumatic nebulizer and on the interface skimmers of the ICP–MS. Nebulization and transport processes can be affected if a matrix component causes a change in surface tension or viscosity. Changes in matrix composition can cause significant signal suppression or enhancement. These interferences are compensated for by use of internal standards. Sample dilution will reduce the effects of high levels of dissolved salts, but calibration standards must be prepared in the extraction medium and diluted accordingly.
4.5 Memory interferences are related to sample transport and result when there is carryover from one sample to the next. Sample carryover can result from sample deposition on the sample and skimmer cones and from incomplete rinsing of the sample solution from the plasma torch and the spray chamber between samples. These memory effects are dependent upon both the analyte being measured and sample matrix and can be minimized through the use of suitable rinse times.
5.1 The toxicity or carcinogenicity of reagents used in this method has not been fully established. Each chemical should be regarded as a potential health hazard and exposure to these compounds should be as low as reasonably achievable. Each laboratory is responsible for maintaining a current file of OSHA regulations regarding the safe handling of the chemicals specified in this method. A reference file of material safety data sheets (MSDSs) should be available to all personnel involved in the chemical analysis. Specifically, concentrated HNO
5.2 Concentrated HNO
1. Safety goggles (or safety glasses with side shields),
2. Acid resistant rubber gloves, and
3. A protective garment such as a laboratory apron. HNO
It is also essential that an eye wash fountain or eye wash bottle be available during performance of this method. An eye wash bottle has a spout that covers the eye. If acid or any other corrosive gets into the eye, the water in this bottle is squirted onto the eye to wash out the harmful material. Eye washing should be performed with large amounts of water immediately after exposure. Medical help should be sought immediately after washing. If either acid, but especially HNO
5.3 Pb salts and Pb solutions are toxic. Great care must be taken to ensure that samples and standards are handled properly; wash hands thoroughly after handling.
5.4 Care must be taken when using the ultrasonic bath and hot block digester as they are capable of causing mild burns. Users should refer to the safety guidance provided by the manufacturer of their specific equipment.
5.5 Analytical plasma sources emit radio frequency radiation in addition to intense ultra violet (UV) radiation. Suitable precautions should be taken to protect personnel from such hazards. The inductively coupled plasma should only be viewed with proper eye protection from UV emissions.
6.1 Thermo Scientific X-Series ICP–MS or equivalent. The system must be capable of providing resolution better or equal to 1.0 atomic mass unit (amu) at 10 percent peak height. The system must have a mass range from at least 7 to 240 amu that allows for the application of the internal standard technique. For the measurement of Pb, an instrument with a collision or reaction cell is not required.
6.2.1 Heated ultrasonic bath capable of maintaining a temperature of 80 °C; VWR Model 750HT, 240W, or equivalent. Ultrasonic bath must meet the following performance criteria:
1. Cut a strip of aluminum foil almost the width of the tank and double the depth.
2. Turn the ultrasonic bath on and lower the foil into the bath vertically until almost touching the bottom of the tank and hold for 10 seconds.
3. Remove the foil from the tank and observe the distribution of perforations and small pin prick holes. The indentations should be fine and evenly distributed. The even distribution of indentations indicates the ultrasonic bath is acceptable for use.
6.2.2 Laboratory centrifuge, Beckman GS–6, or equivalent.
6.2.3 Vortex mixer, VWR Signature Digital Vortex Mixer, VWR Catalog No. 14005–824, or equivalent.
6.3 Hot block extraction equipment
6.3.1 Hot block digester, SCP Science DigiPrep Model MS, No. 010–500–205 block digester capable of maintaining a temperature of 95 °C, or equivalent.
6.4 Materials and Supplies
• Argon gas supply, 99.99 percent purity or better. National Welders Microbulk, or equivalent.
• Plastic digestion tubes with threaded caps for extraction and storage, SCP Science DigiTUBE® Item No. 010–500–063, or equivalent.
• Disposable polypropylene ribbed watch glasses (for heated block extraction), SCP Science Item No. 010–500–081, or equivalent.
• Pipette, Rainin EDP2, 100 µL, ±1 percent accuracy, ≤1 percent RSD (precision), with disposable tips, or equivalent.
• Pipette, Rainin EDP2, 1000 µL, ±1 percent accuracy, ≤1 percent RSD (precision), with disposable tips, or equivalent.
• Pipette, Rainin EDP2, 1–10 mL, ±1 percent accuracy, ≤1 percent RSD (precision), with disposable tips, or equivalent.
• Pipette, Thermo Lab Systems, 5 mL, ±1 percent accuracy, ≤1 percent RSD (precision), with disposable tips, or equivalent.
• Plastic tweezer, VWR Catalog No. 89026–420, or equivalent.
• Laboratory marker.
• Ceramic knife, Kyocera LK–25, and non-metal ruler or other suitable cutting tools for making straight cuts for accurately measured strips.
• Blank labels or labeling tape, VWR Catalog No. 36425–045, or equivalent.
• Graduated cylinder, 1 L, VWR 89000–260, or equivalent.
• Volumetric flask, Class A, 1 L, VWR Catalog No. 89025–778, or equivalent.
• Millipore Element deionized water system, or equivalent, capable of generating water with a resistivity of ≥17.9 MΩ-cm).
• Disposable syringes, 10-mL, with 0.45 micron filters (must be Pb-free).
• Plastic or PTFE wash bottles.
• Glassware, Class A—volumetric flasks, pipettes, and graduated cylinders.
• Glass fiber, quartz, or PTFE filters from the same filter manufacturer and lot used for sample collection for use in the determination of the MDL and for laboratory blanks.
7.1 Reagent—or trace metals-grade chemicals must be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available.
7.2 Concentrated nitric acid, 67–70 percent, SCP Science Catalog No. 250–037–177, or equivalent.
7.3 Concentrated hydrochloric acid (for the ultrasonic extraction method), 33–36 percent, SCP Science Catalog No. 250–037–175, or equivalent.
7.4 Deionized water—All references to deionized water in the method refer to deionized water with a resistivity ≥17.9 MΩ-cm.
7.5 Standard stock solutions may be commercially purchased for each element or as a multi-element mix. Internal standards may be purchased as a mixed multi-element solution. The manufacturer’s expiration date and storage conditions must be adhered to.
7.5.1 Lead standard, 1000 µg/mL, NIST traceable, commercially available with certificate of analysis. High Purity Standards Catalog No. 100028–1, or equivalent.
7.5.2 Indium (In) standard, 1000 µg/mL, NIST traceable, commercially available with certificate of analysis. High Purity Standards Catalog No. 100024–1, or equivalent.
7.5.3 Bismuth (Bi) standard, 1000 µg/mL, NIST traceable, commercially available with certificate of analysis. High Purity Standards Catalog No. 100006–1, or equivalent.
7.5.4 Holmium (Ho) standard, 1000 µg/mL, NIST traceable, commercially available with certificate of analysis. High Purity Standards Catalog No. 100023–1, or equivalent.
7.5.5 Second source lead standard, 1000 µg/mL, NIST traceable, commercially available with certificate of analysis. Must be from a different vendor or lot than the standard described in 7.5.1. Inorganic Ventures Catalog No. CGPB–1, or equivalent.
7.5.6 Standard Reference Materials, NIST SRM 2583, 2586, 2587 or 1648, or equivalent.
Note: The In, Bi, and Ho internal standards may also be purchased as 10 µg/mL standards. Calibration standards are prepared by diluting stock standards to the appropriate levels in the same acid concentrations as in the final sample volume. The typical range for calibration standards is 0.001 to 2.00 µg/mL. At a minimum, the curve must contain a blank and five Pb containing calibration standards. The calibration standards are stored at ambient laboratory temperature. Calibration standards must be prepared weekly and verified against a freshly prepared ICV using a NIST-traceable source different from the calibration standards.
7.6 Internal standards may be added to the test solution or by on-line addition. The nominal concentration for an internal standard is 0.010 µg/mL (10 ppb). Bismuth (Bi) or holmium (Ho) are the preferred internal standards for Pb, but indium (In) may be used in the event the sample contains Bi and high recoveries are observed.
7.7 Three laboratory blank solutions are required for analysis: (1) The calibration blank is used in the construction of the calibration curve and as a periodic check of system cleanliness (ICB and CCB); (2) the reagent blank (RB) is carried through the extraction process to assess possible contamination; and (3) the rinse blank is run between samples to clean the sample introduction system. If RBs or laboratory blanks yield results above the detection limit, the source of contamination must be identified. Screening of labware and reagents is addressed in Section 4.1.
7.7.1 The calibration blank is prepared in the same acid matrix as the calibration standards and samples and contains all internal standards used in the analysis.
7.7.2 The RB contains all reagents used in the extraction and is carried through the extraction procedure at the same time as the samples.
7.7.3 The rinse blank is a solution of 1 to 2 percent HNO
7.7.4 The EPA currently provides glass fiber, quartz, and PTFE filters to air monitoring agencies as requested annually. As part of the procurement process, these filters are tested for acceptance by the EPA. The current acceptance criteria for glass fiber and quartz filters is 15 µg per filter or 0.0075 µg/m
7.7.5 If filters are not provided by the EPA for sample collection and analysis, filter lot blanks should be analyzed for Pb content. For large filter lots (>500 filters), randomly select 20 to 30 filters from the lot and analyze the filter or filter strips for Pb. For smaller filter lots, a lesser number of filters can be analyzed. Glass, quartz and PTFE filters must not have levels of Pb above the criteria specified in section 7.7.4 and, therefore, blank correction should not be performed. If acceptance testing shows levels of Pb above the criteria in Section 7.7.4, corrective action must be taken to reduce the levels before proceeding.
7.8 The Initial Calibration Verification (ICV), Lower Level Calibration Verification (LLCV), and Continuing Calibration Verification (CCV) solutions are prepared from a different Pb source than the calibration curve standards and at a concentration that is either at or below the midpoint on the calibration curve, but within the calibration range. Both are prepared in the same acid matrix as the calibration standards. Note that the same solution may be used for both the ICV and CCV. The ICV/CCV and LLCV solutions must be prepared fresh daily.
7.9 Tuning Solution. Prepare a tuning solution according to the instrument manufacturer’s recommendations. This solution will be used to verify the mass calibration and resolution of the instrument.
8.1 Standard QC practices shall be employed to assess the validity of the data generated, including: MDL, RB, duplicate samples, spiked samples, serial dilutions, ICV, CCV, LLCV, ICB, CCB, and SRMs/CRMs.
8.2 MDLs must be calculated in accordance with 40 CFR part 136, Appendix B. RBs with low-level standard spikes are used to estimate the MDL. The low-level standard spike is added to at least 7 individual filter strips and then carried through the entire extraction procedure. This will result in at least 7 individual samples to be used for the MDL. The recommended range for spiking the strips is 1 to 5 times the estimated MDL.
8.3 For each batch of samples, one RB and one reagent blank spike (RBS) that is spiked at the same level as the sample spike (see Section 8.6) must be prepared and carried throughout the entire process. The results of the RB must be below 0.001 µg/mL. The recovery for the RBS must be within ±20 percent of the expected value. If the RB yields a result above 0.001 µg/mL, the source of contamination must be identified and the extraction and analysis repeated. Reagents and labware must be suspected as sources of contamination. Screening of reagents and labware is addressed in Section 4.1.
8.4 Any samples that exceed the highest calibration standard must be diluted and rerun so that the concentration falls within the curve. The minimum dilution will be 1 to 5 with matrix matched acid solution.
8.5 The internal standard response must be monitored during the analysis. If the internal standard response falls below 70 percent or rises above 120 percent of expected due to possible matrix effects, the sample must be diluted and reanalyzed. The minimum dilution will be 1 to 5 with matrix matched acid solution. If the first dilution does not correct the problem, additional dilutions must be run until the internal standard falls within the specified range.
8.6 For every batch of samples prepared, there must be one duplicate and one spike sample prepared. The spike added is to be at a level that falls within the calibration curve, normally the midpoint of the curve. The initial plus duplicate sample must yield a relative percent difference ≤20 percent. The spike must be within ±20 percent of the expected value.
8.7 For each batch of samples, one extract must be diluted five-fold and analyzed. The corrected dilution result must be within ±10 percent of the undiluted result. The sample chosen for the serial dilution shall have a concentration at or above 10X the lowest standard in the curve to ensure the diluted value falls within the curve. If the serial dilution fails, chemical or physical interference should be suspected.
8.8 ICB, ICV, LLCV, CCB and CCV samples are to be run as shown in the following table.
Sample | Frequency | Performance specification |
---|---|---|
ICB | Prior to first sample | Less than 0.001 µg/mL. |
ICV | Prior to first sample | Within 90 to 110 percent of the expected value. |
LLCV | Daily, before first sample and after last sample | ±10 percent of the expected value. |
CCB | After every 10 extracted samples | Less than 0.001 µg/mL. |
CCV | After every 10 extracted samples | Within 90–110 percent of the expected value. |
If any of these QC samples fails to meet specifications, the source of the unacceptable performance must be determined, the problem corrected, and any samples not bracketed by passing QC samples must be reanalyzed.
8.9 For each batch of samples, one certified reference material (CRM) must be combined with a blank filter strip and carried through the entire extraction procedure. The result must be within ±10 percent of the expected value.
8.10 For each run, a LLCV must be analyzed. The LLCV must be prepared at a concentration not more than three times the lowest calibration standard and at a concentration not used in the calibration curve. The LLCV is used to assess performance at the low end of the curve. If the LLCV fails (±10 percent of the expected value) the run must be terminated, the problem corrected, the instrument recalibrated, and the analysis repeated.
8.11 Pipettes used for volumetric transfer must have the calibration checked at least once every 6 months and pass ±1 percent accuracy and ≤1 percent RSD (precision) based on five replicate readings. The pipettes must be checked weekly for accuracy with a single replicate. Any pipette that does not meet ±1 percent accuracy on the weekly check must be removed from service, repaired, and pass a full calibration check before use.
8.12 Samples with physical deformities are not quantitatively analyzable. The analyst should visually check filters prior to proceeding with preparation for holes, tears, or non-uniform deposit which would prevent representative sampling. Document any deformities and qualify the data with flags appropriately. Care must be taken to protect filters from contamination. Filters must be kept covered prior to sample preparation.
9.0 ICP MS Calibration
Follow the instrument manufacturer’s instructions for the routine maintenance, cleaning, and ignition procedures for the specific ICP–MS instrument being used.
9.1 Ignite the plasma and wait for at least one half hour for the instrument to warm up before beginning any pre-analysis steps.
9.2 For the Thermo X-Series with Xt cones, aspirate a 10 ng/mL tuning solution containing In, Bi, and Ce (Cerium). Monitor the intensities of In, Bi, Ce, and CeO (Cerium oxide) and adjust the instrument settings to achieve the highest In and Bi counts while minimizing the CeO/Ce oxide ratio. For other instruments, follow the manufacturer’s recommended practice. Tune to meet the instrument manufacturer’s specifications. After tuning, place the sample aspiration probe into a 2 percent HNO
9.3 Aspirate a 5 ng/mL solution containing Co, In, and Bi to perform a daily instrument stability check. Run 10 replicates of the solution. The percent RSD for the replicates must be less than 3 percent at all masses. If the percent RSD is greater than 3 percent, the sample introduction system, pump tubing, and tune should be examined, and the analysis repeated. Place the sample aspiration probe into a 2 percent HNO
9.4 Load the calibration standards in the autosampler and analyze using the same method parameters that will be used to analyze samples. The curve must include one blank and at least 5 Pb-containing calibration standards. The correlation coefficient must be at least 0.998 for the curve to be accepted. The lowest standard must recover ±15 percent of the expected value and the remaining standards must recover ±10 percent of the expected value to be accepted.
9.5 Immediately after the calibration curve is completed, analyze an ICV and an ICB. The ICV must be prepared from a different source of Pb than the calibration standards. The ICV must recover 90–110 percent of the expected value for the run to continue. The ICB must be less than 0.001 µg/mL. If either the ICV or the ICB fails, the run must be terminated, the problem identified and corrected, and the analysis re-started.
9.6 A LLCV, CCV and a CCB must be run after the ICV and ICB. A CCV and CCB must be run at a frequency of not less than every 10 extracted samples. A typical analytical run sequence would be: Calibration blank, Calibration standards, ICV, ICB, LLCV, CCV, CCB, Extracts 1–10, CCV, CCB, Extracts 11–20, CCV, CCB, Extracts 21–30, CCV, CCB, LLCV, CCV, CCB. Extracts are any field sample or QC samples that have been carried through the extraction process. The CCV solution is prepared from a different source than the calibration standards and may be the same as the ICV solution. The LLCV must be within ±10 percent of expected value. The CCV value must be within ±10 percent of expected for the run to continue. The CCB must be less than 0.001 µg/mL. If either the CCV, LLCV, or CCB fails, the run must be terminated, the problem identified and corrected, and the analysis re-started from the last passing CCV/LLCV/CCB set.
9.7 A LLCV, CCV, and CCB set must be run at the end of the analysis. The LLCV must be within ±30 percent of expected value. If either the CCV, LLCV, or CCB fails, the run must be terminated, the problem identified and corrected, and the analysis re-started from the last passing CCV/LLCV/CCB set.
All plasticware (e.g., Nalgene) and glassware used in the extraction procedures is soaked in 1 percent HNO
10.1 Sample Preparation—Heated Ultrasonic Bath
10.1.1 Extraction solution (1.03M HNO
10.1.2 Use a ceramic knife and non-metal ruler, or other cutting device that will not contaminate the filter with Pb. Cut a
10.1.3 Using plastic tweezers, roll the filter strip up in a coil and place the rolled strip in the bottom of a labeled 50 mL extraction tube. In a fume hood, add 15.00 ±0.15 mL of the extraction solution (see Section 10.1.1) using a calibrated mechanical pipette. Ensure that the extraction solution completely covers the filter strip.
10.1.4 Loosely cap the 50 mL extraction tube and place it upright in a plastic rack. When all samples have been prepared, place the racks in an uncovered heated ultrasonic water bath that has been preheated to 80 ±5 °C and ensure that the water level in the ultrasonic is above the level of the extraction solution in the tubes but well below the level of the extraction tube caps to avoid contamination. Start the ultrasonic bath and allow the unit to run for 1 hour ±5 minutes at 80 ±5 °C.
10.1.5 Remove the rack(s) from the ultrasonic bath and allow the racks to cool.
10.1.6 Add 25.00 ±0.25 mL of D.I. water with a calibrated mechanical pipette to bring the sample to a final volume of 40.0 ±0.4 mL. Tightly cap the tubes, and vortex mix or shake vigorously. Place the extraction tubes in an appropriate holder and centrifuge for 20 minutes at 2500 revolutions per minute (RPM).
CAUTION—Make sure that the centrifuge holder has a flat bottom to support the flat bottomed extraction tubes.
10.1.7 Pour an aliquot of the solution into an autosampler vial for ICP–MS analysis to avoid the potential for contamination. Do not pipette an aliquot of solution into the autosampler vial.
10.1.8 Decant the extract to a clean tube, cap tightly, and store the sample extract at ambient laboratory temperature. Extracts may be stored for up to 6 months from the date of extraction.
10.2 47 mm PTFE Filter Extraction—Heated Ultrasonic Bath
10.2.1 Extraction solution (1.03M HNO
10.2.2 Using plastic tweezers, bend the PTFE filter into a U-shape and insert the filter into a labeled 50 mL extraction tube with the particle loaded side facing the center of the tube. Gently push the filter to the bottom of the extraction tube. In a fume hood, add 25.00 ±0.15 mL of the extraction solution (see Section 10.2.1) using a calibrated mechanical pipette. Ensure that the extraction solution completely covers the filter.
10.2.3 Loosely cap the 50 mL extraction tube and place it upright in a plastic rack. When all samples have been prepared, place the racks in an uncovered heated ultrasonic water bath that has been preheated to 80 ±5 °C and ensure that the water level in the ultrasonic is above the level of the extraction solution in the tubes, but well below the level of the extraction tube caps to avoid contamination. Start the ultrasonic bath and allow the unit to run for 1 hour ±5 minutes at 80 ±5 °C.
10.2.4 Remove the rack(s) from the ultrasonic bath and allow the racks to cool.
10.2.5 Add 25.00 ±0.25 mL of D.I. water with a calibrated mechanical pipette to bring the sample to a final volume of 50.0 ±0.4 mL. Tightly cap the tubes, and vortex mix or shake vigorously. Allow samples to stand for one hour to allow complete diffusion of the extracted Pb. The sample is now ready for analysis.
Note: Although PTFE filters have only been extracted using the ultrasonic extraction procedure in the development of this FRM, PTFE filters are inert and have very low Pb content. No issues are expected with the extraction of PTFE filters using the heated block digestion method. However, prior to using PTFE filters in the heated block extraction method, extraction method performance test using CRMs must be done to confirm performance (see Section 8.9).
All plasticware (e.g., Nalgene) and glassware used in the extraction procedures is soaked in 1 percent HNO
11.1 Sample Preparation—Hot Block Digestion
11.1.1 Extraction solution (1:19, v/v HNO
11.1.2 Use a ceramic knife and non-metal ruler, or other cutting device that will not contaminate the filter with Pb. Cut a 1-inch × 8-inch strip from the glass fiber or quartz filter. Cut a strip from the edge of the filter where it has been folded along the 10-inch side at least 1 inch from the right or left side to avoid the un-sampled area covered by the filter holder. The filters must be carefully handled to avoid dislodging particle deposits.
11.1.3 Using plastic tweezers, roll the filter strip up in a coil and place the rolled strip in the bottom of a labeled 50 mL extraction tube. In a fume hood, add 20.0 ±0.15 mL of the extraction solution (see Section 11.1.1) using a calibrated mechanical pipette. Ensure that the extraction solution completely covers the filter strip.
11.1.4 Place the extraction tube in the heated block digester and cover with a disposable polyethylene ribbed watch glass. Heat at 95 ±5 °C for 1 hour and ensure that the sample does not evaporate to dryness. For proper heating, adjust the temperature control of the hot block such that an uncovered vessel containing 50 mL of water placed in the center of the hot block can be maintained at a temperature approximately, but no higher than 85C. Once the vessel is covered with a ribbed watch glass, the temperature of the water will increase to approximately 95 °C.
11.1.5 Remove the rack(s) from the heated block digester and allow the samples to cool.
11.1.6 Bring the samples to a final volume of 50 mL with D.I. water. Tightly cap the tubes, and vortex mix or shake vigorously for at least 5 seconds. Set aside (with the filter strip in the tube) for at least 30 minutes to allow the HNO
11.1.7 Shake thoroughly (with the filter strip in the digestion tube) and let settle for at least one hour. The sample is now ready for analysis.
12.1 Follow the instrument manufacturer’s startup procedures for the ICP–MS.
12.2 Set instrument parameters to the appropriate operating conditions as presented in the instrument manufacturer’s operating manual and allow the instrument to warm up for at least 30 minutes.
12.3 Calibrate the instrument per Section 9.0 of this method.
12.4 Verify the instrument is suitable for analysis as defined in Sections 9.2 and 9.3.
12.5 As directed in Section 8.0 of this method, analyze an ICV and ICB immediately after the calibration curve followed by a LLCV, then CCV and CCB. The acceptance requirements for these parameters are presented in Section 8.8.
12.6 Analyze a CCV and a CCB after every 10 extracted samples.
12.7 Analyze a LLCV, CCV and CCB at the end of the analysis.
12.8 A typical sample run will include field samples, field sample duplicates, spiked field sample extracts, serially diluted samples, the set of QC samples listed in Section 8.8 above, and one or more CRMs or SRMs.
12.9 Any samples that exceed the highest standard in the calibration curve must be diluted and reanalyzed so that the diluted concentration falls within the calibration curve.
13.0 Results
13.1 The filter results must be initially reported in µg/mL as analyzed. Any additional dilutions must be accounted for. The internal standard recoveries must be included in the result calculation; this is done by the ICP–MS software for most commercially-available instruments. Final results should be reported in µg Pb/m
The calculation assumes the use of a standard 8-inch × 10-inch TSP filter which has a sampled area of 9-inch × 7-inch (63.0 in
Information in this section is an example of typical performance results achieved by this method. Actual performance must be demonstrated by each individual laboratory and instrument.
14.1 Performance data have been collected to estimate MDLs for this method. MDLs were determined in accordance with 40 CFR 136, Appendix B. MDLs were estimated for glass fiber, quartz, and PTFE filters using seven reagent/filter blank solutions spiked with low level Pb at three times the estimated MDL of 0.001 µg/mL. Tables 1, 3, and 5 shows the MDLs estimated using both the ultrasonic and hot block extraction methods for glass fiber and quartz filters and the ultrasonic method for PTFE filters. The MDLs are well below the EPA requirement of five percent of the current Pb NAAQS or 0.0075 µg/m
14.2 Extraction method recovery tests with glass fiber and quartz filter strips, and PTFE filters spiked with NIST SRMs were performed using the ultrasonic/HNO
Table 1—Method Detection Limits Determined by Analysis of Reagent/Glass Fiber Filter Blanks Spiked With Low-level Pb Solution
Ultrasonic extraction method | Hotblock extraction method | |
---|---|---|
µg/m 3 | µg/m 3 | |
n = 1 | 0.0000702 | 0.000533 |
n = 2 | 0.0000715 | 0.000482 |
n = 3 | 0.0000611 | 0.000509 |
n = 4 | 0.0000587 | 0.000427 |
n = 5 | 0.0000608 | 0.000449 |
n = 6 | 0.0000607 | 0.000539 |
n = 7 | 0.0000616 | 0.000481 |
Average | 0.0000635 | 0.000489 |
Standard Deviation | 0.0000051 | 0.000042 |
MDL** | 0.0000161 | 0.000131 |
* Assumes 2000 m
3 of air sampled.
** MDL is 3.143 times the standard deviation of the results for seven sample replicates analyzed.
Table 2—Recoveries of Lead From NIST SRMs Spiked Onto Glass Fiber Filters
Extraction method | Recovery, ICP–MS, (percent) | |||
---|---|---|---|---|
NIST 1547 plant | NIST 2709 soil | NIST 2583 dust | NIST 2582 paint | |
Ultrasonic Bath | 100 ±4 | 98 ±1 | 103 ±8 | 101 ±0 |
Block Digestion | 92 ±7 | 98 ±3 | 103 ±4 | 94 ±4 |
Table 3—Method Detection Limits Determined by Analysis of Reagent/Quartz Filter Blanks Spiked With Low-level Pb Solution
Ultrasonic extraction method | Hotblock extraction method | |
---|---|---|
µg/m 3* | µg/m 3* | |
n = 1 | 0.000533 | 0.000274 |
n = 2 | 0.000552 | 0.000271 |
n = 3 | 0.000534 | 0.000281 |
n = 4 | 0.000684 | 0.000269 |
n = 5 | 0.000532 | 0.000278 |
n = 6 | 0.000532 | 0.000272 |
n = 7 | 0.000552 | 0.000261 |
Average | 0.000560 | 0.000272 |
Standard Deviation | 0.000055 | 0.000007 |
MDL** | 0.000174 | 0.000021 |
* Assumes 2000 m
3 of air sampled.
** MDL is 3.143 times the standard deviation of the results for seven sample replicates analyzed.
Table 4—Recoveries of Lead From NIST SRMs Spiked Onto Quartz Fiber Filters
Extraction method | Recovery, ICP–MS, (percent) | |||
---|---|---|---|---|
NIST 1547 plant | NIST 2709 soil | NIST 2583 dust | NIST 2582 paint | |
Ultrasonic Bath | 101 ±6 | 95 ±1 | 91 ±5 | 93 ±1 |
Block Digestion | 106 ±3 | 104 ±3 | 92 ±6 | 95 ±2 |
Table 5—Method Detection Limits Determined by Analysis of Reagent/PTFE Filter Blanks Spiked With Low-Level Pb Solution
Ultrasonic extraction method | |
---|---|
µg/m 3* | |
n = 1 | 0.001775 |
n = 2 | 0.001812 |
n = 3 | 0.001773 |
n = 4 | 0.001792 |
n = 5 | 0.001712 |
n = 6 | 0.001767 |
n = 7 | 0.001778 |
Average | 0.001773 |
Standard Deviation | 0.000031 |
MDL** | 0.000097 |
* Assumes 24 m
3 of air sampled.
** MDL is 3.143 times the standard deviation of the results for seven sample replicates analyzed.
Table 6—Recoveries of Lead From NIST SRMs Spiked Onto PTFE Filters
Extraction method | Recovery, ICP–MS, (percent) | |||
---|---|---|---|---|
NIST 1547 plant | NIST 2709 soil | NIST 2583 dust | NIST 2582 paint | |
Ultrasonic Bath | 104 ±5 | 93 ±1 | 108 ±11 | 96 ±3 |
15.1 Pollution prevention encompasses any technique that reduces or eliminates the quantity and/or toxicity of waste at the point of generation. Numerous opportunities for pollution prevention exist in laboratory operations. Whenever feasible, laboratory personnel should use pollution prevention techniques to address their waste generation. The sources of pollution generated with this procedure are waste acid extracts and Pb-containing solutions.
15.2 For information about pollution prevention that may be applicable to laboratories and research institutions, consult Less is Better: Laboratory Chemical Management for Waste Reduction, available from the American Chemical Society’s Department of Government Relations and Science Policy, 1155 16th St. NW., Washington, DC 20036, www.acs.org.
16.1 Laboratory waste management practices must be conducted consistent with all applicable rules and regulations. Laboratories are urged to protect air, water, and land by minimizing all releases from hood and bench operations, complying with the letter and spirit of any sewer and discharge permits and regulations, and by complying with all solid and hazardous waste regulation. For further information on waste management, consult The Waste Management Manual for Laboratory Personnel available from the American Chemical Society listed in Section 15.2 of this method.
16.2 Waste HNO
Appendix H to Part 50—Interpretation of the 1-Hour Primary and Secondary National Ambient Air Quality Standards for Ozone
This appendix explains how to determine when the expected number of days per calendar year with maximum hourly average concentrations above 0.12 ppm (235 µg/m
The basic principle in making this determination is relatively straightforward. Most of the complications that arise in determining the expected number of annual exceedances relate to accounting for incomplete sampling. In general, the average number of exceedances per calendar year must be less than or equal to 1. In its simplest form, the number of exceedances at a monitoring site would be recorded for each calendar year and then averaged over the past 3 calendar years to determine if this average is less than or equal to 1.
The ozone standard states that the expected number of exceedances per year must be less than or equal to 1. The statistical term “expected number” is basically an arithmetic average. The following example explains what it would mean for an area to be in compliance with this type of standard. Suppose a monitoring station records a valid daily maximum hourly average ozone value for every day of the year during the past 3 years. At the end of each year, the number of days with maximum hourly concentrations above 0.12 ppm is determined and this number is averaged with the results of previous years. As long as this average remains “less than or equal to 1,” the area is in compliance.
In general, a valid daily maximum hourly average value may not be available for each day of the year, and it will be necessary to account for these missing values when estimating the number of exceedances for a particular calendar year. The purpose of these computations is to determine if the expected number of exceedances per year is less than or equal to 1. Thus, if a site has two or more observed exceedances each year, the standard is not met and it is not necessary to use the procedures of this section to account for incomplete sampling.
The term “missing value” is used here in the general sense to describe all days that do not have an associated ozone measurement. In some cases, a measurement might actually have been missed but in other cases no measurement may have been scheduled for that day. A daily maximum ozone value is defined to be the highest hourly ozone value recorded for the day. This daily maximum value is considered to be valid if 75 percent of the hours from 9:01 a.m. to 9:00 p.m. (LST) were measured or if the highest hour is greater than the level of the standard.
In some areas, the seasonal pattern of ozone is so pronounced that entire months need not be sampled because it is extremely unlikely that the standard would be exceeded. Any such waiver of the ozone monitoring requirement would be handled under provisions of 40 CFR, part 58. Some allowance should also be made for days for which valid daily maximum hourly values were not obtained but which would quite likely have been below the standard. Such an allowance introduces a complication in that it becomes necessary to define under what conditions a missing value may be assumed to have been less than the level of the standard. The following criterion may be used for ozone:
A missing daily maximum ozone value may be assumed to be less than the level of the standard if the valid daily maxima on both the preceding day and the following day do not exceed 75 percent of the level of the standard.
Let z denote the number of missing daily maximum values that may be assumed to be less than the standard. Then the following formula shall be used to estimate the expected number of exceedances for the year:
(*Indicates multiplication.)
This estimated number of exceedances shall be rounded to one decimal place (fractional parts equal to 0.05 round up).
It should be noted that N will be the total number of days in the year unless the appropriate Regional Administrator has granted a waiver under the provisions of 40 CFR part 58.
The above equation may be interpreted intuitively in the following manner. The estimated number of exceedances is equal to the observed number of exceedances (v) plus an increment that accounts for incomplete sampling. There were (N-n) missing values for the year but a certain number of these, namely z, were assumed to be less than the standard. Therefore, (N-n-z) missing values are considered to include possible exceedances. The fraction of measured values that are above the level of the standard is v/n. It is assumed that this same fraction applies to the (N-n-z) missing values and that (v/n)*(N-n-z) of these values would also have exceeded the level of the standard.
Appendix I to Part 50—Interpretation of the 8-Hour Primary and Secondary National Ambient Air Quality Standards for Ozone
1. General.
This appendix explains the data handling conventions and computations necessary for determining whether the national 8-hour primary and secondary ambient air quality standards for ozone specified in § 50.10 are met at an ambient ozone air quality monitoring site. Ozone is measured in the ambient air by a reference method based on appendix D of this part. Data reporting, data handling, and computation procedures to be used in making comparisons between reported ozone concentrations and the level of the ozone standard are specified in the following sections. Whether to exclude, retain, or make adjustments to the data affected by stratospheric ozone intrusion or other natural events is subject to the approval of the appropriate Regional Administrator.
2. Primary and Secondary Ambient Air Quality Standards for Ozone.
2.1 Data Reporting and Handling Conventions.
2.1.1 Computing 8-hour averages. Hourly average concentrations shall be reported in parts per million (ppm) to the third decimal place, with additional digits to the right being truncated. Running 8-hour averages shall be computed from the hourly ozone concentration data for each hour of the year and the result shall be stored in the first, or start, hour of the 8-hour period. An 8-hour average shall be considered valid if at least 75% of the hourly averages for the 8-hour period are available. In the event that only 6 (or 7) hourly averages are available, the 8-hour average shall be computed on the basis of the hours available using 6 (or 7) as the divisor. (8-hour periods with three or more missing hours shall not be ignored if, after substituting one-half the minimum detectable limit for the missing hourly concentrations, the 8-hour average concentration is greater than the level of the standard.) The computed 8-hour average ozone concentrations shall be reported to three decimal places (the insignificant digits to the right of the third decimal place are truncated, consistent with the data handling procedures for the reported data.)
2.1.2 Daily maximum 8-hour average concentrations. (a) There are 24 possible running 8-hour average ozone concentrations for each calendar day during the ozone monitoring season. (Ozone monitoring seasons vary by geographic location as designated in part 58, appendix D to this chapter.) The daily maximum 8-hour concentration for a given calendar day is the highest of the 24 possible 8-hour average concentrations computed for that day. This process is repeated, yielding a daily maximum 8-hour average ozone concentration for each calendar day with ambient ozone monitoring data. Because the 8-hour averages are recorded in the start hour, the daily maximum 8-hour concentrations from two consecutive days may have some hourly concentrations in common. Generally, overlapping daily maximum 8-hour averages are not likely, except in those non-urban monitoring locations with less pronounced diurnal variation in hourly concentrations.
(b) An ozone monitoring day shall be counted as a valid day if valid 8-hour averages are available for at least 75% of possible hours in the day (i.e., at least 18 of the 24 averages). In the event that less than 75% of the 8-hour averages are available, a day shall also be counted as a valid day if the daily maximum 8-hour average concentration for that day is greater than the level of the ambient standard.
2.2 Primary and Secondary Standard-related Summary Statistic. The standard-related summary statistic is the annual fourth-highest daily maximum 8-hour ozone concentration, expressed in parts per million, averaged over three years. The 3-year average shall be computed using the three most recent, consecutive calendar years of monitoring data meeting the data completeness requirements described in this appendix. The computed 3-year average of the annual fourth-highest daily maximum 8-hour average ozone concentrations shall be expressed to three decimal places (the remaining digits to the right are truncated.)
2.3 Comparisons with the Primary and Secondary Ozone Standards. (a) The primary and secondary ozone ambient air quality standards are met at an ambient air quality monitoring site when the 3-year average of the annual fourth-highest daily maximum 8-hour average ozone concentration is less than or equal to 0.08 ppm. The number of significant figures in the level of the standard dictates the rounding convention for comparing the computed 3-year average annual fourth-highest daily maximum 8-hour average ozone concentration with the level of the standard. The third decimal place of the computed value is rounded, with values equal to or greater than 5 rounding up. Thus, a computed 3-year average ozone concentration of 0.085 ppm is the smallest value that is greater than 0.08 ppm.
(b) This comparison shall be based on three consecutive, complete calendar years of air quality monitoring data. This requirement is met for the three year period at a monitoring site if daily maximum 8-hour average concentrations are available for at least 90%, on average, of the days during the designated ozone monitoring season, with a minimum data completeness in any one year of at least 75% of the designated sampling days. When computing whether the minimum data completeness requirements have been met, meteorological or ambient data may be sufficient to demonstrate that meteorological conditions on missing days were not conducive to concentrations above the level of the standard. Missing days assumed less than the level of the standard are counted for the purpose of meeting the data completeness requirement, subject to the approval of the appropriate Regional Administrator.
(c) Years with concentrations greater than the level of the standard shall not be ignored on the ground that they have less than complete data. Thus, in computing the 3-year average fourth maximum concentration, calendar years with less than 75% data completeness shall be included in the computation if the average annual fourth maximum 8-hour concentration is greater than the level of the standard.
(d) Comparisons with the primary and secondary ozone standards are demonstrated by examples 1 and 2 in paragraphs (d)(1) and (d) (2) respectively as follows:
(1) As shown in example 1, the primary and secondary standards are met at this monitoring site because the 3-year average of the annual fourth-highest daily maximum 8-hour average ozone concentrations (i.e., 0.084 ppm) is less than or equal to 0.08 ppm. The data completeness requirement is also met because the average percent of days with valid ambient monitoring data is greater than 90%, and no single year has less than 75% data completeness.
Example 1. Ambient monitoring site attaining the primary and secondary ozone standards
Year | Percent Valid Days | 1st Highest Daily Max 8-hour Conc. (ppm) | 2nd Highest Daily Max 8-hour Conc. (ppm) | 3rd Highest Daily Max 8-hour Conc. (ppm) | 4th Highest Daily Max 8-hour Conc. (ppm) | 5th Highest Daily Max 8-hour Conc. (ppm) |
---|---|---|---|---|---|---|
1993 | 100% | 0.092 | 0.091 | 0.090 | 0.088 | 0.085 |
1994 | 96% | 0.090 | 0.089 | 0.086 | 0.084 | 0.080 |
1995 | 98% | 0.087 | 0.085 | 0.083 | 0.080 | 0.075 |
Average | 98% |
(2) As shown in example 2, the primary and secondary standards are not met at this monitoring site because the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations (i.e., 0.093 ppm) is greater than 0.08 ppm. Note that the ozone concentration data for 1994 is used in these computations, even though the data capture is less than 75%, because the average fourth-highest daily maximum 8-hour average concentration is greater than 0.08 ppm.
Example 2. Ambient Monitoring Site Failing to Meet the Primary and Secondary Ozone Standards
Year | Percent Valid Days | 1st Highest Daily Max 8-hour Conc. (ppm) | 2nd Highest Daily Max 8-hour Conc. (ppm) | 3rd Highest Daily Max 8-hour Conc. (ppm) | 4th Highest Daily Max 8-hour Conc. (ppm) | 5th Highest Daily Max 8-hour Conc. (ppm) |
---|---|---|---|---|---|---|
1993 | 96% | 0.105 | 0.103 | 0.103 | 0.102 | 0.102 |
1994 | 74% | 0.090 | 0.085 | 0.082 | 0.080 | 0.078 |
1995 | 98% | 0.103 | 0.101 | 0.101 | 0.097 | 0.095 |
Average | 89% |
3. Design Values for Primary and Secondary Ambient Air Quality Standards for Ozone. The air quality design value at a monitoring site is defined as that concentration that when reduced to the level of the standard ensures that the site meets the standard. For a concentration-based standard, the air quality design value is simply the standard-related test statistic. Thus, for the primary and secondary ozone standards, the 3-year average annual fourth-highest daily maximum 8-hour average ozone concentration is also the air quality design value for the site.
Appendix J to Part 50—Reference Method for the Determination of Particulate Matter as PM10 in the Atmosphere
1.0 Applicability.
1.1 This method provides for the measurement of the mass concentration of particulate matter with an aerodynamic diameter less than or equal to a nominal 10 micrometers (PM
2.0 Principle.
2.1 An air sampler draws ambient air at a constant flow rate into a specially shaped inlet where the suspended particulate matter is inertially separated into one or more size fractions within the PM
2.2 Each filter is weighed (after moisture equilibration) before and after use to determine the net weight (mass) gain due to collected PM
2.3 A method based on this principle will be considered a reference method only if (a) the associated sampler meets the requirements specified in this appendix and the requirements in part 53 of this chapter, and (b) the method has been designated as a reference method in accordance with part 53 of this chapter.
3.0 Range.
3.1 The lower limit of the mass concentration range is determined by the repeatability of filter tare weights, assuming the nominal air sample volume for the sampler. For samplers having an automatic filter-changing mechanism, there may be no upper limit. For samplers that do not have an automatic filter-changing mechanism, the upper limit is determined by the filter mass loading beyond which the sampler no longer maintains the operating flow rate within specified limits due to increased pressure drop across the loaded filter. This upper limit cannot be specified precisely because it is a complex function of the ambient particle size distribution and type, humidity, filter type, and perhaps other factors. Nevertheless, all samplers should be capable of measuring 24-hour PM
4.0 Precision.
4.1 The precision of PM
5.0 Accuracy.
5.1 Because the size of the particles making up ambient particulate matter varies over a wide range and the concentration of particles varies with particle size, it is difficult to define the absolute accuracy of PM
6.0 Potential Sources of Error.
6.1 Volatile Particles. Volatile particles collected on filters are often lost during shipment and/or storage of the filters prior to the post-sampling weighing
6.2 Artifacts. Positive errors in PM
6.3 Humidity. The effects of ambient humidity on the sample are unavoidable. The filter equilibration procedure in section 9.0 is designed to minimize the effects of moisture on the filter medium.
6.4 Filter Handling. Careful handling of filters between presampling and postsampling weighings is necessary to avoid errors due to damaged filters or loss of collected particles from the filters. Use of a filter cartridge or cassette may reduce the magnitude of these errors. Filters must also meet the integrity specification in section 7.2.3.
6.5 Flow Rate Variation. Variations in the sampler’s operating flow rate may alter the particle size discrimination characteristics of the sampler inlet. The magnitude of this error will depend on the sensitivity of the inlet to variations in flow rate and on the particle distribution in the atmosphere during the sampling period. The use of a flow control device (section 7.1.3) is required to minimize this error.
6.6 Air Volume Determination. Errors in the air volume determination may result from errors in the flow rate and/or sampling time measurements. The flow control device serves to minimize errors in the flow rate determination, and an elapsed time meter (section 7.1.5) is required to minimize the error in the sampling time measurement.
7.0 Apparatus.
7.1 PM
7.1.1 The sampler shall be designed to:
a. Draw the air sample into the sampler inlet and through the particle collection filter at a uniform face velocity.
b. Hold and seal the filter in a horizontal position so that sample air is drawn downward through the filter.
c. Allow the filter to be installed and removed conveniently.
d. Protect the filter and sampler from precipitation and prevent insects and other debris from being sampled.
e. Minimize air leaks that would cause error in the measurement of the air volume passing through the filter.
f. Discharge exhaust air at a sufficient distance from the sampler inlet to minimize the sampling of exhaust air.
g. Minimize the collection of dust from the supporting surface.
7.1.2 The sampler shall have a sample air inlet system that, when operated within a specified flow rate range, provides particle size discrimination characteristics meeting all of the applicable performance specifications prescribed in part 53 of this chapter. The sampler inlet shall show no significant wind direction dependence. The latter requirement can generally be satisfied by an inlet shape that is circularly symmetrical about a vertical axis.
7.1.3 The sampler shall have a flow control device capable of maintaining the sampler’s operating flow rate within the flow rate limits specified for the sampler inlet over normal variations in line voltage and filter pressure drop.
7.1.4 The sampler shall provide a means to measure the total flow rate during the sampling period. A continuous flow recorder is recommended but not required. The flow measurement device shall be accurate to ±2 percent.
7.1.5 A timing/control device capable of starting and stopping the sampler shall be used to obtain a sample collection period of 24 ±1 hr (1,440 ±60 min). An elapsed time meter, accurate to within ±15 minutes, shall be used to measure sampling time. This meter is optional for samplers with continuous flow recorders if the sampling time measurement obtained by means of the recorder meets the ±15 minute accuracy specification.
7.1.6 The sampler shall have an associated operation or instruction manual as required by part 53 of this chapter which includes detailed instructions on the calibration, operation, and maintenance of the sampler.
7.2 Filters.
7.2.1 Filter Medium. No commercially available filter medium is ideal in all respects for all samplers. The user’s goals in sampling determine the relative importance of various filter characteristics (e.g., cost, ease of handling, physical and chemical characteristics, etc.) and, consequently, determine the choice among acceptable filters. Furthermore, certain types of filters may not be suitable for use with some samplers, particularly under heavy loading conditions (high mass concentrations), because of high or rapid increase in the filter flow resistance that would exceed the capability of the sampler’s flow control device. However, samplers equipped with automatic filter-changing mechanisms may allow use of these types of filters. The specifications given below are minimum requirements to ensure acceptability of the filter medium for measurement of PM
7.2.2 Collection Efficiency. ≥99 percent, as measured by the DOP test (ASTM–2986) with 0.3 µm particles at the sampler’s operating face velocity.
7.2.3 Integrity. ±5 µg/m
7.2.4 Alkalinity.
7.3 Flow Rate Transfer Standard. The flow rate transfer standard must be suitable for the sampler’s operating flow rate and must be calibrated against a primary flow or volume standard that is traceable to the National Bureau of Standards (NBS). The flow rate transfer standard must be capable of measuring the sampler’s operating flow rate with an accuracy of ±2 percent.
7.4 Filter Conditioning Environment.
7.4.1 Temperature range: 15 to 30 C.
7.4.2 Temperature control: ±3 C.
7.4.3 Humidity range: 20% to 45% RH.
7.4.4 Humidity control: ±5% RH.
7.5 Analytical Balance. The analytical balance must be suitable for weighing the type and size of filters required by the sampler. The range and sensitivity required will depend on the filter tare weights and mass loadings. Typically, an analytical balance with a sensitivity of 0.1 mg is required for high volume samplers (flow rates >0.5 m
8.0 Calibration.
8.1 General Requirements.
8.1.1 Calibration of the sampler’s flow measurement device is required to establish traceability of subsequent flow measurements to a primary standard. A flow rate transfer standard calibrated against a primary flow or volume standard shall be used to calibrate or verify the accuracy of the sampler’s flow measurement device.
8.1.2 Particle size discrimination by inertial separation requires that specific air velocities be maintained in the sampler’s air inlet system. Therefore, the flow rate through the sampler’s inlet must be maintained throughout the sampling period within the design flow rate range specified by the manufacturer. Design flow rates are specified as actual volumetric flow rates, measured at existing conditions of temperature and pressure (Q
8.2 Flow Rate Calibration Procedure.
8.2.1 PM
8.2.2 Calibrate the flow rate transfer standard against a primary flow or volume standard traceable to NBS. Establish a calibration relationship (e.g., an equation or family of curves) such that traceability to the primary standard is accurate to within 2 percent over the expected range of ambient conditions (i.e., temperatures and pressures) under which the transfer standard will be used. Recalibrate the transfer standard periodically.
8.2.3 Following the sampler manufacturer’s instruction manual, remove the sampler inlet and connect the flow rate transfer standard to the sampler such that the transfer standard accurately measures the sampler’s flow rate. Make sure there are no leaks between the transfer standard and the sampler.
8.2.4 Choose a minimum of three flow rates (actual m
8.2.5 Following calibration, verify that the sampler is operating at its design flow rate (actual m
8.2.6 Replace the sampler inlet.
9.0 Procedure.
9.1 The sampler shall be operated in accordance with the specific guidance provided in the sampler manufacturer’s instruction manual and in Reference 2. The general procedure given here assumes that the sampler’s flow rate calibration is based on flow rates at ambient conditions (Q
9.2 Inspect each filter for pinholes, particles, and other imperfections. Establish a filter information record and assign an identification number to each filter.
9.3 Equilibrate each filter in the conditioning environment (see 7.4) for at least 24 hours.
9.4 Following equilibration, weigh each filter and record the presampling weight with the filter identification number.
9.5 Install a preweighed filter in the sampler following the instructions provided in the sampler manufacturer’s instruction manual.
9.6 Turn on the sampler and allow it to establish run-temperature conditions. Record the flow indicator reading and, if needed, the ambient temperature and barometric pressure. Determine the sampler flow rate (actual m
9.7 If the flow rate is outside the acceptable range specified by the manufacturer, check for leaks, and if necessary, adjust the flow rate to the specified setpoint. Stop the sampler.
9.8 Set the timer to start and stop the sampler at appropriate times. Set the elapsed time meter to zero or record the initial meter reading.
9.9 Record the sample information (site location or identification number, sample date, filter identification number, and sampler model and serial number).
9.10 Sample for 24 ±1 hours.
9.11 Determine and record the average flow rate (Q
9.12 Carefully remove the filter from the sampler, following the sampler manufacturer’s instruction manual. Touch only the outer edges of the filter.
9.13 Place the filter in a protective holder or container (e.g., petri dish, glassine envelope, or manila folder).
9.14 Record any factors such as meteorological conditions, construction activity, fires or dust storms, etc., that might be pertinent to the measurement on the filter information record.
9.15 Transport the exposed sample filter to the filter conditioning environment as soon as possible for equilibration and subsequent weighing.
9.16 Equilibrate the exposed filter in the conditioning environment for at least 24 hours under the same temperature and humidity conditions used for presampling filter equilibration (see 9.3).
9.17 Immediately after equilibration, reweigh the filter and record the postsampling weight with the filter identification number.
10.0 Sampler Maintenance.
10.1 The PM
11.0 Calculations.
11.1 Calculate the average flow rate over the sampling period corrected to EPA reference conditions as Q
11.2 Calculate the total volume of air sampled as:
11.3 Calculate the PM
If more than one size fraction in the PM
12.0 References.
1. Quality Assurance Handbook for Air Pollution Measurement Systems, Volume I, Principles. EPA–600/9–76–005, March 1976. Available from CERI, ORD Publications, U.S. Environmental Protection Agency, 26 West St. Clair Street, Cincinnati, OH 45268.
2. Quality Assurance Handbook for Air Pollution Measurement Systems, Volume II, Ambient Air Specific Methods. EPA–600/4–77–027a, May 1977. Available from CERI, ORD Publications, U.S. Environmental Protection Agency, 26 West St. Clair Street, Cincinnati, OH 45268.
3. Clement, R.E., and F.W. Karasek. Sample Composition Changes in Sampling and Analysis of Organic Compounds in Aerosols. Int. J. Environ. Analyt. Chem., 7:109, 1979.
4. Lee, R.E., Jr., and J. Wagman. A Sampling Anomaly in the Determination of Atmospheric Sulfate Concentration. Amer. Ind. Hyg. Assoc. J., 27:266, 1966.
5. Appel, B.R., S.M. Wall, Y. Tokiwa, and M. Haik. Interference Effects in Sampling Particulate Nitrate in Ambient Air. Atmos. Environ., 13:319, 1979.
6. Coutant, R.W. Effect of Environmental Variables on Collection of Atmospheric Sulfate. Environ. Sci. Technol., 11:873, 1977.
7. Spicer, C.W., and P. Schumacher. Interference in Sampling Atmospheric Particulate Nitrate. Atmos. Environ., 11:873, 1977.
8. Appel, B.R., Y. Tokiwa, and M. Haik. Sampling of Nitrates in Ambient Air. Atmos. Environ., 15:283, 1981.
9. Spicer, C.W., and P.M. Schumacher. Particulate Nitrate: Laboratory and Field Studies of Major Sampling Interferences. Atmos. Environ., 13:543, 1979.
10. Appel, B.R. Letter to Larry Purdue, U.S. EPA, Environmental Monitoring and Support Laboratory. March 18, 1982, Docket No. A–82–37, II-I-1.
11. Pierson, W.R., W.W. Brachaczek, T.J. Korniski, T.J. Truex, and J.W. Butler. Artifact Formation of Sulfate, Nitrate, and Hydrogen Ion on Backup Filters: Allegheny Mountain Experiment. J. Air Pollut. Control Assoc., 30:30, 1980.
12. Dunwoody, C.L. Rapid Nitrate Loss From PM
13. Harrell, R.M. Measuring the Alkalinity of Hi-Vol Air Filters. EMSL/RTP-SOP-QAD-534, October 1985. Available from the U.S. Environmental Protection Agency, EMSL/QAD, Research Triangle Park, NC 27711.
14. Smith, F., P.S. Wohlschlegel, R.S.C. Rogers, and D.J. Mulligan. Investigation of Flow Rate Calibration Procedures Associated With the High Volume Method for Determination of Suspended Particulates. EPA–600/4–78–047, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, 1978.
Appendix K to Part 50—Interpretation of the National Ambient Air Quality Standards for Particulate Matter
(a) This appendix explains the computations necessary for analyzing particulate matter data to determine attainment of the 24-hour standards specified in 40 CFR 50.6. For the primary and secondary standards, particulate matter is measured in the ambient air as PM
(b) The terms used in this appendix are defined as follows:
Average refers to the arithmetic mean of the estimated number of exceedances per year, as per Section 3.1.
Daily value for PM
Exceedance means a daily value that is above the level of the 24-hour standard after rounding to the nearest 10 µg/m
Expected annual value is the number approached when the annual values from an increasing number of years are averaged, in the absence of long-term trends in emissions or meteorological conditions.
Year refers to a calendar year.
(c) Although the discussion in this appendix focuses on monitored data, the same principles apply to modeling data, subject to EPA modeling guidelines.
(a) Under 40 CFR 50.6(a) the 24-hour primary and secondary standards are attained when the expected number of exceedances per year at each monitoring site is less than or equal to one. In the simplest case, the number of expected exceedances at a site is determined by recording the number of exceedances in each calendar year and then averaging them over the past 3 calendar years. Situations in which 3 years of data are not available and possible adjustments for unusual events or trends are discussed in sections 2.3 and 2.4 of this appendix. Further, when data for a year are incomplete, it is necessary to compute an estimated number of exceedances for that year by adjusting the observed number of exceedances. This procedure, performed by calendar quarter, is described in section 3.0 of this appendix. The expected number of exceedances is then estimated by averaging the individual annual estimates for the past 3 years.
(b) The comparison with the allowable expected exceedance rate of one per year is made in terms of a number rounded to the nearest tenth (fractional values equal to or greater than 0.05 are to be rounded up; e.g., an exceedance rate of 1.05 would be rounded to 1.1, which is the lowest rate for nonattainment).
(a) 40 CFR 58.12 specifies the required minimum frequency of sampling for PM
(b) To demonstrate attainment of the 24-hour standards at a monitoring site, the monitor must provide sufficient data to perform the required calculations of sections 3.0 and 4.0 of this appendix. The amount of data required varies with the sampling frequency, data capture rate and the number of years of record. In all cases, 3 years of representative monitoring data that meet the 75 percent criterion of the previous paragraph should be utilized, if available, and would suffice. More than 3 years may be considered, if all additional representative years of data meeting the 75 percent criterion are utilized. Data not meeting these criteria may also suffice to show attainment; however, such exceptions will have to be approved by the appropriate Regional Administrator in accordance with EPA guidance.
(c) There are less stringent data requirements for showing that a monitor has failed an attainment test and thus has recorded a violation of the particulate matter standards. Although it is generally necessary to meet the minimum 75 percent data capture requirement per quarter to use the computational equations described in section 3.0 of this appendix, this criterion does not apply when less data is sufficient to unambiguously establish nonattainment. The following examples illustrate how nonattainment can be demonstrated when a site fails to meet the completeness criteria. Nonattainment of the 24-hour primary standards can be established by the observed annual number of exceedances (e.g., four observed exceedances in a single year), or by the estimated number of exceedances derived from the observed number of exceedances and the required number of scheduled samples (e.g., two observed exceedances with every other day sampling). In both cases, expected annual values must exceed the levels allowed by the standards.
(a) An exceptional event is an uncontrollable event caused by natural sources of particulate matter or an event that is not expected to recur at a given location. Inclusion of such a value in the computation of exceedances or averages could result in inappropriate estimates of their respective expected annual values. To reduce the effect of unusual events, more than 3 years of representative data may be used. Alternatively, other techniques, such as the use of statistical models or the use of historical data could be considered so that the event may be discounted or weighted according to the likelihood that it will recur. The use of such techniques is subject to the approval of the appropriate Regional Administrator in accordance with EPA guidance.
(b) In cases where long-term trends in emissions and air quality are evident, mathematical techniques should be applied to account for the trends to ensure that the expected annual values are not inappropriately biased by unrepresentative data. In the simplest case, if 3 years of data are available under stable emission conditions, this data should be used. In the event of a trend or shift in emission patterns, either the most recent representative year(s) could be used or statistical techniques or models could be used in conjunction with previous years of data to adjust for trends. The use of less than 3 years of data, and any adjustments are subject to the approval of the appropriate Regional Administrator in accordance with EPA guidance.
(a) If PM
(b) The estimated number of exceedances for a calendar quarter must be rounded to the nearest hundredth (fractional values equal to or greater than 0.005 must be rounded up).
(c) The estimated number of exceedances for the year, e, is the sum of the estimates for each calendar quarter.
(d) The estimated number of exceedances for a single year must be rounded to one decimal place (fractional values equal to or greater than 0.05 are to be rounded up). The expected number of exceedances is then estimated by averaging the individual annual estimates for the most recent 3 or more representative years of data. The expected number of exceedances must be rounded to one decimal place (fractional values equal to or greater than 0.05 are to be rounded up).
(e) The adjustment for incomplete data will not be necessary for monitoring or modeling data which constitutes a complete record, i.e., 365 days per year.
(f) To reduce the potential for overestimating the number of expected exceedances, the correction for missing data will not be required for a calendar quarter in which the first observed exceedance has occurred if:
(1) There was only one exceedance in the calendar quarter;
(2) Everyday sampling is subsequently initiated and maintained for 4 calendar quarters in accordance with 40 CFR 58.12; and
(3) Data capture of 75 percent is achieved during the required period of everyday sampling. In addition, if the first exceedance is observed in a calendar quarter in which the monitor is already sampling every day, no adjustment for missing data will be made to the first exceedance if a 75 percent data capture rate was achieved in the quarter in which it was observed.
a. During a particular calendar quarter, 39 out of a possible 92 samples were recorded, with one observed exceedance of the 24-hour standard. Using Equation 1, the estimated number of exceedances for the quarter is:
b. If the estimated exceedances for the other 3 calendar quarters in the year were 2.30, 0.0 and 0.0, then, using Equation 2, the estimated number of exceedances for the year is 2.36 + 2.30 + 0.0 + 0.0 which equals 4.66 or 4.7. If no exceedances were observed for the 2 previous years, then the expected number of exceedances is estimated by: (
In this example, everyday sampling was initiated following the first observed exceedance as required by 40 CFR 58.12. Accordingly, the first observed exceedance would not be adjusted for incomplete sampling. During the next three quarters, 1.2 exceedances were estimated. In this case, the estimated exceedances for the year would be 1.0 + 1.2 + 0.0 + 0.0 which equals 2.2. If, as before, no exceedances were observed for the two previous years, then the estimated exceedances for the 3-year period would then be (
(a) If a systematic sampling schedule is used and sampling is performed on days in addition to the days specified by the systematic sampling schedule, e.g., during episodes of high pollution, then an adjustment must be made in the equation for the estimation of exceedances. Such an adjustment is needed to eliminate the bias in the estimate of the quarterly and annual number of exceedances that would occur if the chance of an exceedance is different for scheduled than for non-scheduled days, as would be the case with episode sampling.
(b) The required adjustment treats the systematic sampling schedule as a stratified sampling plan. If the period from one scheduled sample until the day preceding the next scheduled sample is defined as a sampling stratum, then there is one stratum for each scheduled sampling day. An average number of observed exceedances is computed for each of these sampling strata. With nonscheduled sampling days, the estimated number of exceedances is defined as:
(c) Note that if only one sample value is recorded in each stratum, then Equation 3 reduces to Equation 1.
A monitoring site samples according to a systematic sampling schedule of one sample every 6 days, for a total of 15 scheduled samples in a quarter out of a total of 92 possible samples. During one 6-day period, potential episode levels of PM
Eq = (92/14) × (2/6 + 0 + . . . + 0) = 2.19.
Appendix L to Part 50—Reference Method for the Determination of Fine Particulate Matter as PM2.5 in the Atmosphere
1.0 Applicability.
1.1 This method provides for the measurement of the mass concentration of fine particulate matter having an aerodynamic diameter less than or equal to a nominal 2.5 micrometers (PM
1.2 This method will be considered a reference method for purposes of part 58 of this chapter only if:
(a) The associated sampler meets the requirements specified in this appendix and the applicable requirements in part 53 of this chapter, and
(b) The method and associated sampler have been designated as a reference method in accordance with part 53 of this chapter.
1.3 PM
2.0 Principle.
2.1 An electrically powered air sampler draws ambient air at a constant volumetric flow rate into a specially shaped inlet and through an inertial particle size separator (impactor) where the suspended particulate matter in the PM
2.2 Each filter is weighed (after moisture and temperature conditioning) before and after sample collection to determine the net gain due to collected PM
3.0 PM
3.1 Lower concentration limit. The lower detection limit of the mass concentration measurement range is estimated to be approximately 2 µg/m
3.2 Upper concentration limit. The upper limit of the mass concentration range is determined by the filter mass loading beyond which the sampler can no longer maintain the operating flow rate within specified limits due to increased pressure drop across the loaded filter. This upper limit cannot be specified precisely because it is a complex function of the ambient particle size distribution and type, humidity, the individual filter used, the capacity of the sampler flow rate control system, and perhaps other factors. Nevertheless, all samplers are estimated to be capable of measuring 24-hour PM
3.3 Sample period. The required sample period for PM
4.0 Accuracy.
4.1 Because the size and volatility of the particles making up ambient particulate matter vary over a wide range and the mass concentration of particles varies with particle size, it is difficult to define the accuracy of PM
4.2 Measurement system bias. Results of collocated measurements where the duplicate sampler is a reference method sampler are used to assess a portion of the measurement system bias according to the schedule and procedure specified in part 58, appendix A of this chapter.
4.3 Audits with reference method samplers to determine system accuracy and bias. According to the schedule and procedure specified in part 58, appendix A of this chapter, a reference method sampler is required to be located at each of selected PM
4.4 Flow rate accuracy and bias. Part 58, appendix A of this chapter requires that the flow rate accuracy and bias of individual PM
5.0 Precision. A data quality objective of 10 percent coefficient of variation or better has been established for the operational precision of PM
5.1 Tests to establish initial operational precision for each reference method sampler are specified as a part of the requirements for designation as a reference method under § 53.58 of this chapter.
5.2 Measurement System Precision. Collocated sampler results, where the duplicate sampler is not a reference method sampler but is a sampler of the same designated method as the primary sampler, are used to assess measurement system precision according to the schedule and procedure specified in part 58, appendix A of this chapter. Part 58, appendix A of this chapter requires that these collocated sampler measurements be used to calculate quarterly and annual precision estimates for each primary sampler and for each designated method employed by each reporting organization. Reference 2 in section 13.0 of this appendix provides additional information and guidance on this requirement.
6.0 Filter for PM
6.1 Size. Circular, 46.2 mm diameter ±0.25 mm.
6.2 Medium. Polytetrafluoroethylene (PTFE Teflon), with integral support ring.
6.3 Support ring. Polymethylpentene (PMP) or equivalent inert material, 0.38 ±0.04 mm thick, outer diameter 46.2 mm ±0.25 mm, and width of 3.68 mm (±0.00, −0.51 mm).
6.4 Pore size. 2 µm as measured by ASTM F 316–94.
6.5 Filter thickness. 30 to 50 µm.
6.6 Maximum pressure drop (clean filter). 30 cm H
6.7 Maximum moisture pickup. Not more than 10 µg weight increase after 24-hour exposure to air of 40 percent relative humidity, relative to weight after 24-hour exposure to air of 35 percent relative humidity.
6.8 Collection efficiency. Greater than 99.7 percent, as measured by the DOP test (ASTM D 2986–91) with 0.3 µm particles at the sampler’s operating face velocity.
6.9 Filter weight stability. Filter weight loss shall be less than 20 µg, as measured in each of the following two tests specified in sections 6.9.1 and 6.9.2 of this appendix. The following conditions apply to both of these tests: Filter weight loss shall be the average difference between the initial and the final filter weights of a random sample of test filters selected from each lot prior to sale. The number of filters tested shall be not less than 0.1 percent of the filters of each manufacturing lot, or 10 filters, whichever is greater. The filters shall be weighed under laboratory conditions and shall have had no air sample passed through them, i.e., filter blanks. Each test procedure must include initial conditioning and weighing, the test, and final conditioning and weighing. Conditioning and weighing shall be in accordance with sections 8.0 through 8.2 of this appendix and general guidance provided in reference 2 of section 13.0 of this appendix.
6.9.1 Test for loose, surface particle contamination. After the initial weighing, install each test filter, in turn, in a filter cassette (Figures L–27, L–28, and L–29 of this appendix) and drop the cassette from a height of 25 cm to a flat hard surface, such as a particle-free wood bench. Repeat two times, for a total of three drop tests for each test filter. Remove the test filter from the cassette and weigh the filter. The average change in weight must be less than 20 µg.
6.9.2 Test for temperature stability. After weighing each filter, place the test filters in a drying oven set at 40 °C ±2 °C for not less than 48 hours. Remove, condition, and reweigh each test filter. The average change in weight must be less than 20 µg.
6.10 Alkalinity. Less than 25 microequivalents/gram of filter, as measured by the guidance given in reference 2 in section 13.0 of this appendix.
6.11 Supplemental requirements. Although not required for determination of PM
7.0 PM
7.1 Configuration. The sampler shall consist of a sample air inlet, downtube, particle size separator (impactor), filter holder assembly, air pump and flow rate control system, flow rate measurement device, ambient and filter temperature monitoring system, barometric pressure measurement system, timer, outdoor environmental enclosure, and suitable mechanical, electrical, or electronic control capability to meet or exceed the design and functional performance as specified in this section 7.0 of this appendix. The performance specifications require that the sampler:
(a) Provide automatic control of sample volumetric flow rate and other operational parameters.
(b) Monitor these operational parameters as well as ambient temperature and pressure.
(c) Provide this information to the sampler operator at the end of each sample period in digital form, as specified in table L–1 of section 7.4.19 of this appendix.
7.2 Nature of specifications. The PM
7.3 Design specifications. Except as indicated in this section 7.3 of this appendix, these components must be manufactured or reproduced exactly as specified, in an ISO 9001-registered facility, with registration initially approved and subsequently maintained during the period of manufacture. See § 53.1(t) of this chapter for the definition of an ISO-registered facility. Minor modifications or variances to one or more components that clearly would not affect the aerodynamic performance of the inlet, downtube, impactor, or filter cassette will be considered for specific approval. Any such proposed modifications shall be described and submitted to the EPA for specific individual acceptability either as part of a reference or equivalent method application under part 53 of this chapter or in writing in advance of such an intended application under part 53 of this chapter.
7.3.1 Sample inlet assembly. The sample inlet assembly, consisting of the inlet, downtube, and impactor shall be configured and assembled as indicated in Figure L–1 of this appendix and shall meet all associated requirements. A portion of this assembly shall also be subject to the maximum overall sampler leak rate specification under section 7.4.6 of this appendix.
7.3.2 Inlet. The sample inlet shall be fabricated as indicated in Figures L–2 through L–18 of this appendix and shall meet all associated requirements.
7.3.3 Downtube. The downtube shall be fabricated as indicated in Figure L–19 of this appendix and shall meet all associated requirements.
7.3.4 Particle size separator. The sampler shall be configured with either one of the two alternative particle size separators described in this section 7.3.4. One separator is an impactor-type separator (WINS impactor) described in sections 7.3.4.1, 7.3.4.2, and 7.3.4.3 of this appendix. The alternative separator is a cyclone-type separator (VSCC
7.3.4.1 The impactor (particle size separator) shall be fabricated as indicated in Figures L–20 through L–24 of this appendix and shall meet all associated requirements. Following the manufacture and finishing of each upper impactor housing (Figure L–21 of this appendix), the dimension of the impaction jet must be verified by the manufacturer using Class ZZ go/no-go plug gauges that are traceable to NIST.
7.3.4.2 Impactor filter specifications:
(a) Size. Circular, 35 to 37 mm diameter.
(b) Medium. Borosilicate glass fiber, without binder.
(c) Pore size. 1 to 1.5 micrometer, as measured by ASTM F 316–80.
(d) Thickness. 300 to 500 micrometers.
7.3.4.3 Impactor oil specifications:
(a) Composition. Dioctyl sebacate (DOS), single-compound diffusion oil.
(b) Vapor pressure. Maximum 2 × 10
(c) Viscosity. 36 to 40 centistokes at 25 °C.
(d) Density. 1.06 to 1.07 g/cm
(e) Quantity. 1 mL ±0.1 mL.
7.3.4.4 The cyclone-type separator is identified as a BGI VSCC
7.3.5 Filter holder assembly. The sampler shall have a sample filter holder assembly to adapt and seal to the down tube and to hold and seal the specified filter, under section 6.0 of this appendix, in the sample air stream in a horizontal position below the downtube such that the sample air passes downward through the filter at a uniform face velocity. The upper portion of this assembly shall be fabricated as indicated in Figures L–25 and L–26 of this appendix and shall accept and seal with the filter cassette, which shall be fabricated as indicated in Figures L–27 through L–29 of this appendix.
(a) The lower portion of the filter holder assembly shall be of a design and construction that:
(1) Mates with the upper portion of the assembly to complete the filter holder assembly,
(2) Completes both the external air seal and the internal filter cassette seal such that all seals are reliable over repeated filter changings, and
(3) Facilitates repeated changing of the filter cassette by the sampler operator.
(b) Leak-test performance requirements for the filter holder assembly are included in section 7.4.6 of this appendix.
(c) If additional or multiple filters are stored in the sampler as part of an automatic sequential sample capability, all such filters, unless they are currently and directly installed in a sampling channel or sampling configuration (either active or inactive), shall be covered or (preferably) sealed in such a way as to:
(1) Preclude significant exposure of the filter to possible contamination or accumulation of dust, insects, or other material that may be present in the ambient air, sampler, or sampler ventilation air during storage periods either before or after sampling; and
(2) To minimize loss of volatile or semi-volatile PM sample components during storage of the filter following the sample period.
7.3.6 Flow rate measurement adapter. A flow rate measurement adapter as specified in Figure L–30 of this appendix shall be furnished with each sampler.
7.3.7 Surface finish. All internal surfaces exposed to sample air prior to the filter shall be treated electrolytically in a sulfuric acid bath to produce a clear, uniform anodized surface finish of not less than 1000 mg/ft
7.3.8 Sampling height. The sampler shall be equipped with legs, a stand, or other means to maintain the sampler in a stable, upright position and such that the center of the sample air entrance to the inlet, during sample collection, is maintained in a horizontal plane and is 2.0 ±0.2 meters above the floor or other horizontal supporting surface. Suitable bolt holes, brackets, tie-downs, or other means should be provided to facilitate mechanically securing the sample to the supporting surface to prevent toppling of the sampler due to wind.
7.4 Performance specifications.
7.4.1 Sample flow rate. Proper operation of the impactor requires that specific air velocities be maintained through the device. Therefore, the design sample air flow rate through the inlet shall be 16.67 L/min (1.000 m
7.4.2 Sample air flow rate control system. The sampler shall have a sample air flow rate control system which shall be capable of providing a sample air volumetric flow rate within the specified range, under section 7.4.1 of this appendix, for the specified filter, under section 6.0 of this appendix, at any atmospheric conditions specified, under section 7.4.7 of this appendix, at a filter pressure drop equal to that of a clean filter plus up to 75 cm water column (55 mm Hg), and over the specified range of supply line voltage, under section 7.4.15.1 of this appendix. This flow control system shall allow for operator adjustment of the operational flow rate of the sampler over a range of at least ±15 percent of the flow rate specified in section 7.4.1 of this appendix.
7.4.3 Sample flow rate regulation. The sample flow rate shall be regulated such that for the specified filter, under section 6.0 of this appendix, at any atmospheric conditions specified, under section 7.4.7 of this appendix, at a filter pressure drop equal to that of a clean filter plus up to 75 cm water column (55 mm Hg), and over the specified range of supply line voltage, under section 7.4.15.1 of this appendix, the flow rate is regulated as follows:
7.4.3.1 The volumetric flow rate, measured or averaged over intervals of not more than 5 minutes over a 24-hour period, shall not vary more than ±5 percent from the specified 16.67 L/min flow rate over the entire sample period.
7.4.3.2 The coefficient of variation (sample standard deviation divided by the mean) of the flow rate, measured over a 24-hour period, shall not be greater than 2 percent.
7.4.3.3 The amplitude of short-term flow rate pulsations, such as may originate from some types of vacuum pumps, shall be attenuated such that they do not cause significant flow measurement error or affect the collection of particles on the particle collection filter.
7.4.4 Flow rate cut off. The sampler’s sample air flow rate control system shall terminate sample collection and stop all sample flow for the remainder of the sample period in the event that the sample flow rate deviates by more than 10 percent from the sampler design flow rate specified in section 7.4.1 of this appendix for more than 60 seconds. However, this sampler cut-off provision shall not apply during periods when the sampler is inoperative due to a temporary power interruption, and the elapsed time of the inoperative period shall not be included in the total sample time measured and reported by the sampler, under section 7.4.13 of this appendix.
7.4.5 Flow rate measurement.
7.4.5.1 The sampler shall provide a means to measure and indicate the instantaneous sample air flow rate, which shall be measured as volumetric flow rate at the temperature and pressure of the sample air entering the inlet, with an accuracy of ±2 percent. The measured flow rate shall be available for display to the sampler operator at any time in either sampling or standby modes, and the measurement shall be updated at least every 30 seconds. The sampler shall also provide a simple means by which the sampler operator can manually start the sample flow temporarily during non-sampling modes of operation, for the purpose of checking the sample flow rate or the flow rate measurement system.
7.4.5.2 During each sample period, the sampler’s flow rate measurement system shall automatically monitor the sample volumetric flow rate, obtaining flow rate measurements at intervals of not greater than 30 seconds.
(a) Using these interval flow rate measurements, the sampler shall determine or calculate the following flow-related parameters, scaled in the specified engineering units:
(1) The instantaneous or interval-average flow rate, in L/min.
(2) The value of the average sample flow rate for the sample period, in L/min.
(3) The value of the coefficient of variation (sample standard deviation divided by the average) of the sample flow rate for the sample period, in percent.
(4) The occurrence of any time interval during the sample period in which the measured sample flow rate exceeds a range of ±5 percent of the average flow rate for the sample period for more than 5 minutes, in which case a warning flag indicator shall be set.
(5) The value of the integrated total sample volume for the sample period, in m
(b) Determination or calculation of these values shall properly exclude periods when the sampler is inoperative due to temporary interruption of electrical power, under section 7.4.13 of this appendix, or flow rate cut off, under section 7.4.4 of this appendix.
(c) These parameters shall be accessible to the sampler operator as specified in table L–1 of section 7.4.19 of this appendix. In addition, it is strongly encouraged that the flow rate for each 5-minute interval during the sample period be available to the operator following the end of the sample period.
7.4.6 Leak test capability.
7.4.6.1 External leakage. The sampler shall include an external air leak-test capability consisting of components, accessory hardware, operator interface controls, a written procedure in the associated Operation/Instruction Manual, under section 7.4.18 of this appendix, and all other necessary functional capability to permit and facilitate the sampler operator to conveniently carry out a leak test of the sampler at a field monitoring site without additional equipment. The sampler components to be subjected to this leak test include all components and their interconnections in which external air leakage would or could cause an error in the sampler’s measurement of the total volume of sample air that passes through the sample filter.
(a) The suggested technique for the operator to use for this leak test is as follows:
(1) Remove the sampler inlet and installs the flow rate measurement adapter supplied with the sampler, under section 7.3.6 of this appendix.
(2) Close the valve on the flow rate measurement adapter and use the sampler air pump to draw a partial vacuum in the sampler, including (at least) the impactor, filter holder assembly (filter in place), flow measurement device, and interconnections between these devices, of at least 55 mm Hg (75 cm water column), measured at a location downstream of the filter holder assembly.
(3) Plug the flow system downstream of these components to isolate the components under vacuum from the pump, such as with a built-in valve.
(4) Stop the pump.
(5) Measure the trapped vacuum in the sampler with a built-in pressure measuring device.
(6) (i) Measure the vacuum in the sampler with the built-in pressure measuring device again at a later time at least 10 minutes after the first pressure measurement.
(ii)
(7) Upon completion of the test, open the adaptor valve, remove the adaptor and plugs, and restore the sampler to the normal operating configuration.
(b) The associated leak test procedure shall require that for successful passage of this test, the difference between the two pressure measurements shall not be greater than the number of mm of Hg specified for the sampler by the manufacturer, based on the actual internal volume of the sampler, that indicates a leak of less than 80 mL/min.
(c) Variations of the suggested technique or an alternative external leak test technique may be required for samplers whose design or configuration would make the suggested technique impossible or impractical. The specific proposed external leak test procedure, or particularly an alternative leak test technique, proposed for a particular candidate sampler may be described and submitted to the EPA for specific individual acceptability either as part of a reference or equivalent method application under part 53 of this chapter or in writing in advance of such an intended application under part 53 of this chapter.
7.4.6.2 Internal, filter bypass leakage. The sampler shall include an internal, filter bypass leak-check capability consisting of components, accessory hardware, operator interface controls, a written procedure in the Operation/Instruction Manual, and all other necessary functional capability to permit and facilitate the sampler operator to conveniently carry out a test for internal filter bypass leakage in the sampler at a field monitoring site without additional equipment. The purpose of the test is to determine that any portion of the sample flow rate that leaks past the sample filter without passing through the filter is insignificant relative to the design flow rate for the sampler.
(a) The suggested technique for the operator to use for this leak test is as follows:
(1) Carry out an external leak test as provided under section 7.4.6.1 of this appendix which indicates successful passage of the prescribed external leak test.
(2) Install a flow-impervious membrane material in the filter cassette, either with or without a filter, as appropriate, which effectively prevents air flow through the filter.
(3) Use the sampler air pump to draw a partial vacuum in the sampler, downstream of the filter holder assembly, of at least 55 mm Hg (75 cm water column).
(4) Plug the flow system downstream of the filter holder to isolate the components under vacuum from the pump, such as with a built-in valve.
(5) Stop the pump.
(6) Measure the trapped vacuum in the sampler with a built-in pressure measuring device.
(7) Measure the vacuum in the sampler with the built-in pressure measuring device again at a later time at least 10 minutes after the first pressure measurement.
(8) Remove the flow plug and membrane and restore the sampler to the normal operating configuration.
(b) The associated leak test procedure shall require that for successful passage of this test, the difference between the two pressure measurements shall not be greater than the number of mm of Hg specified for the sampler by the manufacturer, based on the actual internal volume of the portion of the sampler under vacuum, that indicates a leak of less than 80 mL/min.
(c) Variations of the suggested technique or an alternative internal, filter bypass leak test technique may be required for samplers whose design or configuration would make the suggested technique impossible or impractical. The specific proposed internal leak test procedure, or particularly an alternative internal leak test technique proposed for a particular candidate sampler may be described and submitted to the EPA for specific individual acceptability either as part of a reference or equivalent method application under part 53 of this chapter or in writing in advance of such intended application under part 53 of this chapter.
7.4.7 Range of operational conditions. The sampler is required to operate properly and meet all requirements specified in this appendix over the following operational ranges.
7.4.7.1 Ambient temperature. −30 to = 45 °C (Note: Although for practical reasons, the temperature range over which samplers are required to be tested under part 53 of this chapter is −20 to = 40 °C, the sampler shall be designed to operate properly over this wider temperature range.).
7.4.7.2 Ambient relative humidity. 0 to 100 percent.
7.4.7.3 Barometric pressure range. 600 to 800 mm Hg.
7.4.8 Ambient temperature sensor. The sampler shall have capability to measure the temperature of the ambient air surrounding the sampler over the range of −30 to = 45 °C, with a resolution of 0.1 °C and accuracy of ±2.0 °C, referenced as described in reference 3 in section 13.0 of this appendix, with and without maximum solar insolation.
7.4.8.1 The ambient temperature sensor shall be mounted external to the sampler enclosure and shall have a passive, naturally ventilated sun shield. The sensor shall be located such that the entire sun shield is at least 5 cm above the horizontal plane of the sampler case or enclosure (disregarding the inlet and downtube) and external to the vertical plane of the nearest side or protuberance of the sampler case or enclosure. The maximum temperature measurement error of the ambient temperature measurement system shall be less than 1.6 °C at 1 m/s wind speed and 1000 W/m2 solar radiation intensity.
7.4.8.2 The ambient temperature sensor shall be of such a design and mounted in such a way as to facilitate its convenient dismounting and immersion in a liquid for calibration and comparison to the filter temperature sensor, under section 7.4.11 of this appendix.
7.4.8.3 This ambient temperature measurement shall be updated at least every 30 seconds during both sampling and standby (non-sampling) modes of operation. A visual indication of the current (most recent) value of the ambient temperature measurement, updated at least every 30 seconds, shall be available to the sampler operator during both sampling and standby (non-sampling) modes of operation, as specified in table L–1 of section 7.4.19 of this appendix.
7.4.8.4 This ambient temperature measurement shall be used for the purpose of monitoring filter temperature deviation from ambient temperature, as required by section 7.4.11 of this appendix, and may be used for purposes of effecting filter temperature control, under section 7.4.10 of this appendix, or computation of volumetric flow rate, under sections 7.4.1 to 7.4.5 of this appendix, if appropriate.
7.4.8.5 Following the end of each sample period, the sampler shall report the maximum, minimum, and average temperature for the sample period, as specified in table L–1 of section 7.4.19 of this appendix.
7.4.9 Ambient barometric sensor. The sampler shall have capability to measure the barometric pressure of the air surrounding the sampler over a range of 600 to 800 mm Hg referenced as described in reference 3 in section 13.0 of this appendix; also see part 53, subpart E of this chapter. This barometric pressure measurement shall have a resolution of 5 mm Hg and an accuracy of ±10 mm Hg and shall be updated at least every 30 seconds. A visual indication of the value of the current (most recent) barometric pressure measurement, updated at least every 30 seconds, shall be available to the sampler operator during both sampling and standby (non-sampling) modes of operation, as specified in table L–1 of section 7.4.19 of this appendix. This barometric pressure measurement may be used for purposes of computation of volumetric flow rate, under sections 7.4.1 to 7.4.5 of this appendix, if appropriate. Following the end of a sample period, the sampler shall report the maximum, minimum, and mean barometric pressures for the sample period, as specified in table L–1 of section 7.4.19 of this appendix.
7.4.10 Filter temperature control (sampling and post-sampling). The sampler shall provide a means to limit the temperature rise of the sample filter (all sample filters for sequential samplers), from insolation and other sources, to no more 5 °C above the temperature of the ambient air surrounding the sampler, during both sampling and post-sampling periods of operation. The post-sampling period is the non-sampling period between the end of the active sampling period and the time of retrieval of the sample filter by the sampler operator.
7.4.11 Filter temperature sensor(s).
7.4.11.1 The sampler shall have the capability to monitor the temperature of the sample filter (all sample filters for sequential samplers) over the range of −30 to = 45 °C during both sampling and non-sampling periods. While the exact location of this temperature sensor is not explicitly specified, the filter temperature measurement system must demonstrate agreement, within 1 °C, with a test temperature sensor located within 1 cm of the center of the filter downstream of the filter during both sampling and non-sampling modes, as specified in the filter temperature measurement test described in part 53, subpart E of this chapter. This filter temperature measurement shall have a resolution of 0.1 °C and accuracy of ±1.0 °C, referenced as described in reference 3 in section 13.0 of this appendix. This temperature sensor shall be of such a design and mounted in such a way as to facilitate its reasonably convenient dismounting and immersion in a liquid for calibration and comparison to the ambient temperature sensor under section 7.4.8 of this appendix.
7.4.11.2 The filter temperature measurement shall be updated at least every 30 seconds during both sampling and standby (non-sampling) modes of operation. A visual indication of the current (most recent) value of the filter temperature measurement, updated at least every 30 seconds, shall be available to the sampler operator during both sampling and standby (non-sampling) modes of operation, as specified in table L–1 of section 7.4.19 of this appendix.
7.4.11.3 For sequential samplers, the temperature of each filter shall be measured individually unless it can be shown, as specified in the filter temperature measurement test described in § 53.57 of this chapter, that the temperature of each filter can be represented by fewer temperature sensors.
7.4.11.4 The sampler shall also provide a warning flag indicator following any occurrence in which the filter temperature (any filter temperature for sequential samplers) exceeds the ambient temperature by more than 5 °C for more than 30 consecutive minutes during either the sampling or post-sampling periods of operation, as specified in table L–1 of section 7.4.19 of this appendix, under section 10.12 of this appendix, regarding sample validity when a warning flag occurs. It is further recommended (not required) that the sampler be capable of recording the maximum differential between the measured filter temperature and the ambient temperature and its time and date of occurrence during both sampling and post-sampling (non-sampling) modes of operation and providing for those data to be accessible to the sampler operator following the end of the sample period, as suggested in table L–1 of section 7.4.19 of this appendix.
7.4.12 Clock/timer system.
(a) The sampler shall have a programmable real-time clock timing/control system that:
(1) Is capable of maintaining local time and date, including year, month, day-of-month, hour, minute, and second to an accuracy of ±1.0 minute per month.
(2) Provides a visual indication of the current system time, including year, month, day-of-month, hour, and minute, updated at least each minute, for operator verification.
(3) Provides appropriate operator controls for setting the correct local time and date.
(4) Is capable of starting the sample collection period and sample air flow at a specific, operator-settable time and date, and stopping the sample air flow and terminating the sampler collection period 24 hours (1440 minutes) later, or at a specific, operator-settable time and date.
(b) These start and stop times shall be readily settable by the sampler operator to within ±1.0 minute. The system shall provide a visual indication of the current start and stop time settings, readable to ±1.0 minute, for verification by the operator, and the start and stop times shall also be available via the data output port, as specified in table L–1 of section 7.4.19 of this appendix. Upon execution of a programmed sample period start, the sampler shall automatically reset all sample period information and warning flag indications pertaining to a previous sample period. Refer also to section 7.4.15.4 of this appendix regarding retention of current date and time and programmed start and stop times during a temporary electrical power interruption.
7.4.13 Sample time determination. The sampler shall be capable of determining the elapsed sample collection time for each PM
7.4.14 Outdoor environmental enclosure. The sampler shall have an outdoor enclosure (or enclosures) suitable to protect the filter and other non-weatherproof components of the sampler from precipitation, wind, dust, extremes of temperature and humidity; to help maintain temperature control of the filter (or filters, for sequential samplers); and to provide reasonable security for sampler components and settings.
7.4.15 Electrical power supply.
7.4.15.1 The sampler shall be operable and function as specified herein when operated on an electrical power supply voltage of 105 to 125 volts AC (RMS) at a frequency of 59 to 61 Hz. Optional operation as specified at additional power supply voltages and/or frequencies shall not be precluded by this requirement.
7.4.15.2 The design and construction of the sampler shall comply with all applicable National Electrical Code and Underwriters Laboratories electrical safety requirements.
7.4.15.3 The design of all electrical and electronic controls shall be such as to provide reasonable resistance to interference or malfunction from ordinary or typical levels of stray electromagnetic fields (EMF) as may be found at various monitoring sites and from typical levels of electrical transients or electronic noise as may often or occasionally be present on various electrical power lines.
7.4.15.4 In the event of temporary loss of electrical supply power to the sampler, the sampler shall not be required to sample or provide other specified functions during such loss of power, except that the internal clock/timer system shall maintain its local time and date setting within ±1 minute per week, and the sampler shall retain all other time and programmable settings and all data required to be available to the sampler operator following each sample period for at least 7 days without electrical supply power. When electrical power is absent at the operator-set time for starting a sample period or is interrupted during a sample period, the sampler shall automatically start or resume sampling when electrical power is restored, if such restoration of power occurs before the operator-set stop time for the sample period.
7.4.15.5 The sampler shall have the capability to record and retain a record of the year, month, day-of-month, hour, and minute of the start of each power interruption of more than 1 minute duration, up to 10 such power interruptions per sample period. (More than 10 such power interruptions shall invalidate the sample, except where an exceedance is measured, under section 3.3 of this appendix.) The sampler shall provide for these power interruption data to be available to the sampler operator following the end of the sample period, as specified in table L–1 of section 7.4.19 of this appendix.
7.4.16 Control devices and operator interface. The sampler shall have mechanical, electrical, or electronic controls, control devices, electrical or electronic circuits as necessary to provide the timing, flow rate measurement and control, temperature control, data storage and computation, operator interface, and other functions specified. Operator-accessible controls, data displays, and interface devices shall be designed to be simple, straightforward, reliable, and easy to learn, read, and operate under field conditions. The sampler shall have provision for operator input and storage of up to 64 characters of numeric (or alphanumeric) data for purposes of site, sampler, and sample identification. This information shall be available to the sampler operator for verification and change and for output via the data output port along with other data following the end of a sample period, as specified in table L–1 of section 7.4.19 of this appendix. All data required to be available to the operator following a sample collection period or obtained during standby mode in a post-sampling period shall be retained by the sampler until reset, either manually by the operator or automatically by the sampler upon initiation of a new sample collection period.
7.4.17 Data output port requirement. The sampler shall have a standard RS–232C data output connection through which digital data may be exported to an external data storage or transmission device. All information which is required to be available at the end of each sample period shall be accessible through this data output connection. The information that shall be accessible though this output port is summarized in table L–1 of section 7.4.19 of this appendix. Since no specific format for the output data is provided, the sampler manufacturer or vendor shall make available to sampler purchasers appropriate computer software capable of receiving exported sampler data and correctly translating the data into a standard spreadsheet format and optionally any other formats as may be useful to sampler users. This requirement shall not preclude the sampler from offering other types of output connections in addition to the required RS–232C port.
7.4.18 Operation/instruction manual. The sampler shall include an associated comprehensive operation or instruction manual, as required by part 53 of this chapter, which includes detailed operating instructions on the setup, operation, calibration, and maintenance of the sampler. This manual shall provide complete and detailed descriptions of the operational and calibration procedures prescribed for field use of the sampler and all instruments utilized as part of this reference method. The manual shall include adequate warning of potential safety hazards that may result from normal use or malfunction of the method and a description of necessary safety precautions. The manual shall also include a clear description of all procedures pertaining to installation, operation, periodic and corrective maintenance, and troubleshooting, and shall include parts identification diagrams.
7.4.19 Data reporting requirements. The various information that the sampler is required to provide and how it is to be provided is summarized in the following table L–1.
Table L–1 to Appendix L of Part 50—Summary of Information To Be Provided by the Sampler
Information to be provided | Appendix L section reference | Availability | Format | ||||
---|---|---|---|---|---|---|---|
Anytime 1 | End of period 2 | Visual display 3 | Data output 4 | Digital reading 5 | Units | ||
Flow rate, 30-second maximum interval | 7.4.5.1 | ✓ | ✓ | * | XX.X | L/min | |
Flow rate, average for the sample period | 7.4.5.2 | * | ✓ | * | ✓ | XX.X | L/min |
Flow rate, CV, for sample period | 7.4.5.2 | * | ✓ | * | ✓ | XX.X | % |
Flow rate, 5-min. average out of spec. (FLAG 6) | 7.4.5.2 | ✓ | ✓ | ✓ | ✓▪ | On/Off | |
Sample volume, total | 7.4.5.2 | * | ✓ | ✓ | ✓ | XX.X | m 3 |
Temperature, ambient, 30-second interval | 7.4.8 | ✓ | ✓ | XX.X | °C | ||
Temperature, ambient, min., max., average for the sample period | 7.4.8 | * | ✓ | ✓ | ✓▪ | XX.X | °C |
Baro. pressure, ambient, 30-second interval | 7.4.9 | ✓ | ✓ | XXX | mm Hg | ||
Baro. pressure, ambient, min., max., average for the sample period | 7.4.9 | * | ✓ | ✓ | ✓▪ | XXX | mm Hg |
Filter temperature, 30-second interval | 7.4.11 | ✓ | ✓ | XX.X | °C | ||
Filter temp. differential, 30-second interval, out of spec. (FLAG 6) | 7.4.11 | * | ✓ | ✓ | ✓▪ | On/Off | |
Filter temp., maximum differential from ambient, date, time of occurrence | 7.4.11 | * | * | * | * | X.X, YY/MM/DD HH.mm | °C, Yr/Mon/Day Hrs. min |
Date and Time | 7.4.12 | ✓ | ✓ | YY/MM/DD HH.mm | Yr/Mon/Day Hrs. min | ||
Sample start and stop time settings | 7.4.12 | ✓ | ✓ | ✓ | ✓ | YY/MM/DD HH.mm | Yr/Mon/Day Hrs. min |
Sample period start time | 7.4.12 | ✓ | ✓ | ✓ | YY/MM/DD HH.mm | Yr/Mon/Day Hrs. min | |
Elapsed sample time | 7.4.13 | * | ✓ | ✓ | ✓ | HH.mm | Hrs. min |
Elapsed sample time, out of spec. (FLAG 6) | 7.4.13 | ✓ | ✓ | ✓▪ | On/Off | ||
Power interruptions ≤1 min., start time of first 10 | 7.4.15.5 | * | ✓ | * | ✓ | 1HH.mm, 2HH.mm, etc. | Hrs. min |
User-entered information, such as sampler and site identification | 7.4.16 | ✓ | ✓ | ✓ | ✓▪ | As entered |
✓ Provision of this information is required.
* Provision of this information is optional. If information related to the entire sample period is optionally provided prior to the end of the sample period, the value provided should be the value calculated for the portion of the sampler period completed up to the time the information is provided.
▪ Indicates that this information is also required to be provided to the Air Quality System (AQS) data bank; see § 58.16 of this chapter. For ambient temperature and barometric pressure, only the average for the sample period must be reported.
1. Information is required to be available to the operator at any time the sampler is operating, whether sampling or not.
2. Information relates to the entire sampler period and must be provided following the end of the sample period until reset manually by the operator or automatically by the sampler upon the start of a new sample period.
3. Information shall be available to the operator visually.
4. Information is to be available as digital data at the sampler’s data output port specified in section 7.4.16 of this appendix following the end of the sample period until reset manually by the operator or automatically by the sampler upon the start of a new sample period.
5. Digital readings, both visual and data output, shall have not less than the number of significant digits and resolution specified.
6. Flag warnings may be displayed to the operator by a single flag indicator or each flag may be displayed individually. Only a set (on) flag warning must be indicated; an off (unset) flag may be indicated by the absence of a flag warning. Sampler users should refer to section 10.12 of this appendix regarding the validity of samples for which the sampler provided an associated flag warning.
8.0 Filter Weighing. See reference 2 in section 13.0 of this appendix, for additional, more detailed guidance.
8.1 Analytical balance. The analytical balance used to weigh filters must be suitable for weighing the type and size of filters specified, under section 6.0 of this appendix, and have a readability of ±1 µg. The balance shall be calibrated as specified by the manufacturer at installation and recalibrated immediately prior to each weighing session. See reference 2 in section 13.0 of this appendix for additional guidance.
8.2 Filter conditioning. All sample filters used shall be conditioned immediately before both the pre- and post-sampling weighings as specified below. See reference 2 in section 13.0 of this appendix for additional guidance.
8.2.1 Mean temperature. 20 – 23 °C.
8.2.2 Temperature control. ±2 °C over 24 hours.
8.2.3 Mean humidity. Generally, 30–40 percent relative humidity; however, where it can be shown that the mean ambient relative humidity during sampling is less than 30 percent, conditioning is permissible at a mean relative humidity within ±5 relative humidity percent of the mean ambient relative humidity during sampling, but not less than 20 percent.
8.2.4 Humidity control. ±5 relative humidity percent over 24 hours.
8.2.5 Conditioning time. Not less than 24 hours.
8.3 Weighing procedure.
8.3.1 New filters should be placed in the conditioning environment immediately upon arrival and stored there until the pre-sampling weighing. See reference 2 in section 13.0 of this appendix for additional guidance.
8.3.2 The analytical balance shall be located in the same controlled environment in which the filters are conditioned. The filters shall be weighed immediately following the conditioning period without intermediate or transient exposure to other conditions or environments.
8.3.3 Filters must be conditioned at the same conditions (humidity within ±5 relative humidity percent) before both the pre- and post-sampling weighings.
8.3.4 Both the pre- and post-sampling weighings should be carried out on the same analytical balance, using an effective technique to neutralize static charges on the filter, under reference 2 in section 13.0 of this appendix. If possible, both weighings should be carried out by the same analyst.
8.3.5 The pre-sampling (tare) weighing shall be within 30 days of the sampling period.
8.3.6 The post-sampling conditioning and weighing shall be completed within 240 hours (10 days) after the end of the sample period, unless the filter sample is maintained at temperatures below the average ambient temperature during sampling (or 4 °C or below for average sampling temperatures less than 4 °C) during the time between retrieval from the sampler and the start of the conditioning, in which case the period shall not exceed 30 days. Reference 2 in section 13.0 of this appendix has additional guidance on transport of cooled filters.
8.3.7 Filter blanks.
8.3.7.1 New field blank filters shall be weighed along with the pre-sampling (tare) weighing of each lot of PM
8.3.7.2 New laboratory blank filters shall be weighed along with the pre-sampling (tare) weighing of each set of PM
8.3.8 Additional guidance for proper filter weighing and related quality assurance activities is provided in reference 2 in section 13.0 of this appendix.
9.0 Calibration. Reference 2 in section 13.0 of this appendix contains additional guidance.
9.1 General requirements.
9.1.1 Multipoint calibration and single-point verification of the sampler’s flow rate measurement device must be performed periodically to establish and maintain traceability of subsequent flow measurements to a flow rate standard.
9.1.2 An authoritative flow rate standard shall be used for calibrating or verifying the sampler’s flow rate measurement device with an accuracy of ±2 percent. The flow rate standard shall be a separate, stand-alone device designed to connect to the flow rate measurement adapter, Figure L–30 of this appendix. This flow rate standard must have its own certification and be traceable to a National Institute of Standards and Technology (NIST) primary standard for volume or flow rate. If adjustments to the sampler’s flow rate measurement system calibration are to be made in conjunction with an audit of the sampler’s flow measurement system, such adjustments shall be made following the audit. Reference 2 in section 13.0 of this appendix contains additional guidance.
9.1.3 The sampler’s flow rate measurement device shall be re-calibrated after electromechanical maintenance or transport of the sampler.
9.2 Flow rate calibration/verification procedure.
9.2.1 PM
9.2.2 The flow rate standard used for flow rate calibration shall have its own certification and be traceable to a NIST primary standard for volume or flow rate. A calibration relationship for the flow rate standard, e.g., an equation, curve, or family of curves relating actual flow rate (Q
9.2.3 The sampler flow rate measurement device shall be calibrated or verified by removing the sampler inlet and connecting the flow rate standard to the sampler’s downtube in accordance with the operation/instruction manual, such that the flow rate standard accurately measures the sampler’s flow rate. The sampler operator shall first carry out a sampler leak check and confirm that the sampler passes the leak test and then verify that no leaks exist between the flow rate standard and the sampler.
9.2.4 The calibration relationship between the flow rate (in actual L/min) indicated by the flow rate standard and by the sampler’s flow rate measurement device shall be established or verified in accordance with the sampler operation/instruction manual. Temperature and pressure corrections to the flow rate indicated by the flow rate standard may be required for certain types of flow rate standards. Calibration of the sampler’s flow rate measurement device shall consist of at least three separate flow rate measurements (multipoint calibration) evenly spaced within the range of −10 percent to = 10 percent of the sampler’s operational flow rate, section 7.4.1 of this appendix. Verification of the sampler’s flow rate shall consist of one flow rate measurement at the sampler’s operational flow rate. The sampler operation/instruction manual and reference 2 in section 13.0 of this appendix provide additional guidance.
9.2.5 If during a flow rate verification the reading of the sampler’s flow rate indicator or measurement device differs by ±4 percent or more from the flow rate measured by the flow rate standard, a new multipoint calibration shall be performed and the flow rate verification must then be repeated.
9.2.6 Following the calibration or verification, the flow rate standard shall be removed from the sampler and the sampler inlet shall be reinstalled. Then the sampler’s normal operating flow rate (in L/min) shall be determined with a clean filter in place. If the flow rate indicated by the sampler differs by ±2 percent or more from the required sampler flow rate, the sampler flow rate must be adjusted to the required flow rate, under section 7.4.1 of this appendix.
9.3 Periodic calibration or verification of the calibration of the sampler’s ambient temperature, filter temperature, and barometric pressure measurement systems is also required. Reference 3 of section 13.0 of this appendix contains additional guidance.
10.0 PM
10.1 The sampler shall be set up, calibrated, and operated in accordance with the specific, detailed guidance provided in the specific sampler’s operation or instruction manual and in accordance with a specific quality assurance program developed and established by the user, based on applicable supplementary guidance provided in reference 2 in section 13.0 of this appendix.
10.2 Each new sample filter shall be inspected for correct type and size and for pinholes, particles, and other imperfections. Unacceptable filters should be discarded. A unique identification number shall be assigned to each filter, and an information record shall be established for each filter. If the filter identification number is not or cannot be marked directly on the filter, alternative means, such as a number-identified storage container, must be established to maintain positive filter identification.
10.3 Each filter shall be conditioned in the conditioning environment in accordance with the requirements specified in section 8.2 of this appendix.
10.4 Following conditioning, each filter shall be weighed in accordance with the requirements specified in section 8.0 of this appendix and the presampling weight recorded with the filter identification number.
10.5 A numbered and preweighed filter shall be installed in the sampler following the instructions provided in the sampler operation or instruction manual.
10.6 The sampler shall be checked and prepared for sample collection in accordance with instructions provided in the sampler operation or instruction manual and with the specific quality assurance program established for the sampler by the user.
10.7 The sampler’s timer shall be set to start the sample collection at the beginning of the desired sample period and stop the sample collection 24 hours later.
10.8 Information related to the sample collection (site location or identification number, sample date, filter identification number, and sampler model and serial number) shall be recorded and, if appropriate, entered into the sampler.
10.9 The sampler shall be allowed to collect the PM
10.10 Within 177 hours (7 days, 9 hours) of the end of the sample collection period, the filter, while still contained in the filter cassette, shall be carefully removed from the sampler, following the procedure provided in the sampler operation or instruction manual and the quality assurance program, and placed in a protective container. The protective container shall contain no loose material that could be transferred to the filter. The protective container shall hold the filter cassette securely such that the cover shall not come in contact with the filter’s surfaces. Reference 2 in section 13.0 of this appendix contains additional information.
10.11 The total sample volume in actual m
10.12 All factors related to the validity or representativeness of the sample, such as sampler tampering or malfunctions, unusual meteorological conditions, construction activity, fires or dust storms, etc. shall be recorded as required by the local quality assurance program. The occurrence of a flag warning during a sample period shall not necessarily indicate an invalid sample but rather shall indicate the need for specific review of the QC data by a quality assurance officer to determine sample validity.
10.13 After retrieval from the sampler, the exposed filter containing the PM
10.14. The exposed filter containing the PM
10.15. The filter shall be reweighed immediately after conditioning in accordance with the requirements specified in section 8.0 of this appendix, and the postsampling weight shall be recorded with the filter identification number.
10.16 The PM
11.0 Sampler Maintenance. The sampler shall be maintained as described by the sampler’s manufacturer in the sampler-specific operation or instruction manual required under section 7.4.18 of this appendix and in accordance with the specific quality assurance program developed and established by the user based on applicable supplementary guidance provided in reference 2 in section 13.0 of this appendix.
12.0 Calculations
12.1 (a) The PM
Total sample time must be between 1,380 and 1,500 minutes (23 and 25 hrs) for a fully valid PM
13.0 References.
1. Quality Assurance Handbook for Air Pollution Measurement Systems, Volume I, Principles. EPA/600/R–94/038a, April 1994. Available from CERI, ORD Publications, U.S. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, Ohio 45268.
2. Quality Assurance Guidance Document 2.12. Monitoring PM
3. Quality Assurance Handbook for Air Pollution Measurement Systems, Volume IV: Meteorological Measurements, (Revised Edition) EPA/600/R–94/038d, March, 1995. Available from CERI, ORD Publications, U.S. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, Ohio 45268.
4. Military standard specification (mil. spec.) 8625F, Type II, Class 1 as listed in Department of Defense Index of Specifications and Standards (DODISS), available from DODSSP-Customer Service, Standardization Documents Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia, PA 1911–5094.
14.0 Figures L–1 through L–30 to Appendix L.






























Appendix M to Part 50 [Reserved]
Appendix N to Part 50—Interpretation of the National Ambient Air Quality Standards for PM2.5
(a) This appendix explains the data handling conventions and computations necessary for determining when the national ambient air quality standards (NAAQS) for PM
(b) Decisions to exclude, retain, or make adjustments to the data affected by exceptional events, including natural events, are made according to the requirements and process deadlines specified in §§ 50.1, 50.14 and 51.930 of this chapter.
(c) The terms used in this appendix are defined as follows:
Annual mean refers to a weighted arithmetic mean, based on quarterly means, as defined in section 4.4 of this appendix.
The Air Quality System (AQS) is EPA’s official repository of ambient air data.
Collocated monitors refers to two or more air measurement instruments for the same parameter (e.g., PM
Combined site data record is the data set used for performing calculations in appendix N. It represents data for the primary monitors augmented with data from collocated monitors according to the procedure specified in section 3.0(d) of this appendix.
Creditable samples are daily values in the combined site record that are given credit for data completeness. The number of creditable samples (cn) for a given year also governs which value in the sorted series of daily values represents the 98th percentile for that year. Creditable samples include daily values collected on scheduled sampling days and valid make-up samples taken for missed or invalidated samples on scheduled sampling days.
Daily values refer to the 24-hour average concentrations of PM
Data substitution tests are diagnostic evaluations performed on an annual PM
(1) The 3-year average of PM
(2) The 3-year average of annual 98th percentile 24-hour average PM
Eligible sites are monitoring stations that meet the criteria specified in § 58.11 and § 58.30 of this chapter, and thus are approved for comparison to the annual PM
Extra samples are non-creditable samples. They are daily values that do not occur on scheduled sampling days and that cannot be used as make-up samples for missed or invalidated scheduled samples. Extra samples are used in mean calculations and are included in the series of all daily values subject to selection as a 98th percentile value, but are not used to determine which value in the sorted list represents the 98th percentile.
Make-up samples are samples collected to take the place of missed or invalidated required scheduled samples. Make-up samples can be made by either the primary or the collocated monitor. Make-up samples are either taken before the next required sampling day or exactly one week after the missed (or voided) sampling day.
The maximum quarterly value data substitution test substitutes actual “high” reported daily PM
The minimum quarterly value data substitution test substitutes actual “low” reported daily PM
98th percentile is the smallest daily value out of a year of PM
Primary monitors are suitable monitors designated by a state or local agency in their annual network plan (and in AQS) as the default data source for creating a combined site record for purposes of NAAQS comparisons. If there is only one suitable monitor at a particular site location, then it is presumed to be a primary monitor.
Quarter refers to a calendar quarter (e.g., January through March).
Quarterly data capture rate is the percentage of scheduled samples in a calendar quarter that have corresponding valid reported sample values. Quarterly data capture rates are specifically calculated as the number of creditable samples for the quarter divided by the number of scheduled samples for the quarter, the result then multiplied by 100 and rounded to the nearest integer.
Scheduled PM
Seasonal sampling is the practice of collecting data at a reduced frequency during a season of expected low concentrations.
Suitable monitors are instruments that use sampling and analysis methods approved for NAAQS comparisons. For the annual and 24-hour PM
Test design values (TDV) are numerical values that used in the data substitution tests described in sections 4.1(c)(i), 4.1(c)(ii) and 4.2(c)(i) of this appendix to determine if the PM
Year refers to a calendar year.
(a) Section 58.30 of this chapter provides special considerations for data comparisons to the annual PM
(b) Monitors meeting the network technical requirements detailed in § 58.11 of this chapter are suitable for comparison with the NAAQS for PM
(c) Section 58.12 of this chapter specifies the required minimum frequency of sampling for PM
(a) Except as otherwise provided in this appendix, all valid FRM/FEM/ARM PM
(b) PM
(c) Twenty-four-hour average concentrations will be computed in AQS from submitted hourly PM
(d) All calculations shown in this appendix shall be implemented on a site-level basis. Site level concentration data shall be processed as follows:
(1) The default dataset for PM
(2) Data for the primary monitors shall be augmented as much as possible with data from collocated monitors. If a valid daily value is not produced by the primary monitor for a particular day (scheduled or otherwise), but a value is available from a collocated monitor, then that collocated value shall be considered part of the combined site data record. If more than one collocated daily value is available, the average of those valid collocated values shall be used as the daily value. The data record resulting from this procedure is referred to as the “combined site data record.”
(e) All daily values in a combined site data record are used in the calculations specified in this appendix; however, not all daily values are given credit towards data completeness requirements. Only creditable samples are given credit for data completeness. Creditable samples include daily values in the combined site record that are collected on scheduled sampling days and valid make-up samples taken for missed or invalidated samples on scheduled sampling days. Days are considered scheduled according to the required sampling frequency of the designated primary monitor with one exception. The exception is, if a collocated continuous FEM/ARM monitor has a more intensive sampling frequency than the primary FRM monitor, then samples contributed to the combined site record from that continuous FEM/ARM monitor are always considered scheduled and, hence, also creditable. Daily values in the combined site data record that are reported for nonscheduled days, but that are not valid make-up samples are referred to as extra samples.
(a) The primary annual PM
(b) Three years of valid annual means are required to produce a valid annual PM
(c) In the case of one, two, or three years that do not meet the completeness requirements of section 4.1(b) of this appendix and thus would normally not be useable for the calculation of a valid annual PM
(i) An annual PM
Procedure: Identify for each deficient quarter (i.e., those with less than 11 creditable samples) the lowest reported daily value for that quarter, looking across those three months of all three years under consideration. If after substituting the lowest reported daily value for a quarter for (11− cn) daily values in the matching deficient quarter(s) (i.e., to bring the creditable number for those quarters up to 11), the procedure yields a recalculated annual PM
(ii) An annual PM
Procedure: Identify for each deficient quarter (i.e., those with less than 75 percent but at least 50 percent data capture) the highest reported daily value for that quarter, excluding state-flagged data affected by exceptional events which have been approved for exclusion by the Administrator, looking across those three quarters of all three years under consideration. If after substituting the highest reported daily PM
(d) An annual PM
(e) The equations for calculating the annual PM
(a) The primary and secondary 24-hour PM
(b) Three years of valid annual PM
(c) In the case of one, two, or three years that do not meet the completeness requirements of section 4.2(b) of this appendix and thus would normally not be useable for the calculation of a valid 24-hour PM
(i) A PM
Procedure: Identify for each deficient quarter (i.e., those with less than 75 percent but at least 50 percent data capture) the highest reported daily PM
(d) A 24-hour PM
(e) The procedures and equations for calculating the 24-hour PM
4.3 Rounding Conventions. For the purposes of comparing calculated PM
(a) Annual PM
(b) Twenty-four-hour PM
(a) An annual mean value for PM

(b) Equation 2 of this appendix is then used to calculate the site annual mean:

(c) The annual PM

(d) The annual PM
(a) When the data for a particular site and year meet the data completeness requirements in section 4.2 of this appendix, calculation of the 98th percentile is accomplished by the steps provided in this subsection. Table 1 of this appendix shall be used to identify annual 98th percentile values.
Identification of annual 98th percentile values using the Table 1 procedure will be based on the creditable number of samples (as described below), rather than on the actual number of samples. Credit will not be granted for extra (non-creditable) samples. Extra samples, however, are candidates for selection as the annual 98th percentile. [The creditable number of samples will determine how deep to go into the data distribution, but all samples (creditable and extra) will be considered when making the percentile assignment.] The annual creditable number of samples is the sum of the four quarterly creditable number of samples.
Procedure: Sort all the daily values from a particular site and year by descending value. (For example: (x[1], x[2], x[3], * * *, x[n]). In this case, x[1] is the largest number and x[n] is the smallest value.) The 98th percentile value is determined from this sorted series of daily values which is ordered from the highest to the lowest number. Using the left column of Table 1, determine the appropriate range for the annual creditable number of samples for year y (cn
Table 1
Annual number of creditable samples for year | The 98th percentile for year y (P th maximum 24-hour average value for the year where |
---|---|
1 to 50 | 1 |
51 to 100 | 2 |
101 to 150 | 3 |
151 to 200 | 4 |
201 to 250 | 5 |
251 to 300 | 6 |
301 to 350 | 7 |
351 to 366 | 8 |
(b) The 24-hour PM

P
P
(c) The 24-hour PM
Appendix O to Part 50—Reference Method for the Determination of Coarse Particulate Matter as PM10–2.5 in the Atmosphere
1.1 This method provides for the measurement of the mass concentration of coarse particulate matter (PM
1.2 For the purpose of this method, PM
1.3 For this reference method, PM
1.4 The PM
1.5 Quality assessment procedures are provided in part 58, appendix A of this chapter. The quality assurance procedures and guidance provided in reference 1 in section 13 of this appendix, although written specifically for PM
1.6 A method based on specific model PM
(a) The PM
(b) The method based on the specific samplers and associated operational procedures have been designated as a reference method in accordance with part 53 of this chapter.
1.7 PM
1.8 PM
1.9 PM
(a) The PM
(b) Such PM
2.1 Separate, collocated, electrically powered air samplers for PM
2.2 Each PM
2.3 Most requirements for PM
3.1 Lower concentration limit. The lower detection limit of the mass concentration measurement range is estimated to be approximately 3 µg/m
3.2 Upper concentration limit. The upper limit of the mass concentration range is determined principally by the PM
3.3 Sample period. The required sample period for PM
4.1 Because the size, density, and volatility of the particles making up ambient particulate matter vary over wide ranges and the mass concentration of particles varies with particle size, it is difficult to define the accuracy of PM
4.2 Measurement system bias for monitoring data is assessed according to the procedures and schedule set forth in part 58, appendix A of this chapter. The goal for the measurement uncertainty (as bias) for monitoring data is defined in part 58, appendix A of this chapter as an upper 95 percent confidence limit for the absolute bias of 15 percent. Reference 1 in section 13 of this appendix provides additional information and guidance on flow rate accuracy audits and assessment of bias.
5.1 Tests to establish initial measurement precision for each sampler of the reference method sampler pair are specified as a part of the requirements for designation as a reference method under part 53 of this chapter.
5.2 Measurement system precision is assessed according to the procedures and schedule set forth in appendix A to part 58 of this chapter. The goal for acceptable measurement uncertainty, as precision, of monitoring data is defined in part 58, appendix A of this chapter as an upper 95 percent confidence limit for the coefficient of variation (CV) of 15 percent. Reference 1 in section 13 of this appendix provides additional information and guidance on this requirement.
6.0 Filters for PM
7.0 Sampler. The PM
7.1 The PM
7.2 The PM
7.2.1 The particle size separator specified in section 7.3.4 of appendix L to this part shall be eliminated and replaced by a downtube extension fabricated as specified in Figure O–1 of this appendix.
7.2.2 The sampler shall be identified as a PM
7.2.3 The average temperature and average barometric pressure measured by the sampler during the sample period, as described in Table L–1 of appendix L to this part, need not be reported to EPA’s AQS data base, as required by section 7.4.19 and Table L–1 of appendix L to this part, provided such measurements for the sample period determined by the associated PM
7.3 In addition to the operation/instruction manual required by section 7.4.18 of appendix L to this part for each sampler, supplemental operational instructions shall be provided for the simultaneous operation of the samplers as a pair to collect concurrent PM
7.4 Capability for electrical interconnection of the samplers to simplify sample period programming and further ensure simultaneous operation is encouraged but not required. Any such capability for interconnection shall not supplant each sampler’s capability to operate independently, as required by section 7 of appendix L of this part.
8.1 Conditioning and weighing for both PM
8.2 Handling, conditioning, and weighing for both PM
8.3 Due care shall be exercised to accurately maintain the paired relationship of each set of concurrently collected PM
9.0 Calibration. Calibration of the flow rate, temperature measurement, and pressure measurement systems for both the PM
10.1 The PM
10.2 The measurement procedure for PM
10.3 The measurement procedure for PM
10.4 For the PM
10.5 Retrieval, transport, and storage of each PM
11.0 Sampler Maintenance. Both PM
12.1 Both concurrent PM
12.2 The PM
Total sample time must be between 1,380 and 1,500 minutes (23 and 25 hrs) for a fully valid PM
12.3 The PM
12.4 The PM
1. Quality Assurance Guidance Document 2.12. Monitoring PM
Figure O–1 is included as part of this appendix O.
Appendix P to Part 50—Interpretation of the Primary and Secondary National Ambient Air Quality Standards for Ozone
(a) This appendix explains the data handling conventions and computations necessary for determining whether the national 8-hour primary and secondary ambient air quality standards for ozone (O
(b) The terms used in this appendix are defined as follows:
8-hour average is the rolling average of eight hourly O
Annual fourth-highest daily maximum refers to the fourth highest value measured at a monitoring site during a particular year.
Daily maximum 8-hour average concentration refers to the maximum calculated 8-hour average for a particular day as explained in section 2 of this appendix.
Design values are the metrics (i.e., statistics) that are compared to the NAAQS levels to determine compliance, calculated as shown in section 3 of this appendix.
O
Year refers to calendar year.
Computing 8-hour averages. Hourly average concentrations shall be reported in parts per million (ppm) to the third decimal place, with additional digits to the right of the third decimal place truncated. Running 8-hour averages shall be computed from the hourly O
Daily maximum 8-hour average concentrations. (a) There are 24 possible running 8-hour average O
(b) An O
The standard-related summary statistic is the annual fourth-highest daily maximum 8-hour O
(a) The primary and secondary O
(b) This comparison shall be based on three consecutive, complete calendar years of air quality monitoring data. This requirement is met for the 3-year period at a monitoring site if daily maximum 8-hour average concentrations are available for at least 90% of the days within the O
(c) Years with concentrations greater than the level of the standard shall be included even if they have less than complete data. Thus, in computing the 3-year average fourth maximum concentration, calendar years with less than 75% data completeness shall be included in the computation if the 3-year average fourth-highest 8-hour concentration is greater than the level of the standard.
(d) Comparisons with the primary and secondary O
Example 1—Ambient Monitoring Site Attaining the Primary and Secondary O
Year | Percent valid days (within the required monitoring season) | 1st Highest daily max 8-hour Conc. (ppm) | 2nd Highest daily max 8-hour Conc. (ppm) | 3rd Highest daily max 8-hour Conc. (ppm) | 4th Highest daily max 8-hour Conc. (ppm) | 5th Highest daily max 8-hour Conc. (ppm) |
---|---|---|---|---|---|---|
2004 | 100 | 0.092 | 0.090 | 0.085 | 0.079 | 0.078 |
2005 | 96 | 0.084 | 0.083 | 0.075 | 0.072 | 0.070 |
2006 | 98 | 0.080 | 0.079 | 0.077 | 0.076 | 0.060 |
Average | 98 | 0.075 |
(1) As shown in Example 1, this monitoring site meets the primary and secondary O
Example 2—Ambient Monitoring Site Failing to Meet the Primary and Secondary O
Year | Percent valid days (within the required monitoring season) | 1st Highest daily max 8-hour Conc. (ppm) | 2nd Highest daily max 8-hour Conc. (ppm) | 3rd Highest daily max 8-hour Conc. (ppm) | 4th Highest daily max 8-hour Conc. (ppm) | 5th Highest daily max 8-hour Conc. (ppm) |
---|---|---|---|---|---|---|
2004 | 96 | 0.105 | 0.103 | 0.103 | 0.103 | 0.102 |
2005 | 74 | 0.104 | 0.103 | 0.092 | 0.091 | 0.088 |
2006 | 98 | 0.103 | 0.101 | 0.101 | 0.095 | 0.094 |
Average | 89 | 0.096 |
As shown in Example 2, the primary and secondary O
The air quality design value at a monitoring site is defined as that concentration that when reduced to the level of the standard ensures that the site meets the standard. For a concentration-based standard, the air quality design value is simply the standard-related test statistic. Thus, for the primary and secondary standards, the 3-year average annual fourth-highest daily maximum 8-hour average O
Appendix Q to Part 50—Reference Method for the Determination of Lead in Particulate Matter as PM10 Collected From Ambient Air
This Federal Reference Method (FRM) draws heavily from the specific analytical protocols used by the U.S. EPA.
1. Applicability and Principle
1.1 This method provides for the measurement of the lead (Pb) concentration in particulate matter that is 10 micrometers or less (PM
1.2 For this reference method, PM
1.3 The FRM will serve as the basis for approving Federal Equivalent Methods (FEMs) as specified in 40 CFR Part 53 (Reference and Equivalent Methods). This FRM specifically applies to the analysis of Pb in PM
1.4 The PM
1.5 Quality assurance (QA) procedures for the collection of monitoring data are contained in Part 58, appendix A.
2. PM
2.1 EDXRF Pb Measurement Range. The typical ambient air measurement range is 0.001 to 30 µg Pb/m
2.2 Detection Limit (DL). A typical estimate of the one-sigma detection limit (DL) is about 2 ng Pb/cm
3. Factors Affecting Bias and Precision of Lead Determination by EDXRF
3.1 Filter Deposit. X-ray spectra are subject to distortion if unusually heavy deposits are analyzed. This is the result of internal absorption of both primary and secondary X-rays within the sample; however, this is not an issue for Pb due to the energetic X-rays used to fluoresce Pb and the energetic characteristic X-rays emitted by Pb. The optimum mass filter loading for multi-elemental EDXRF analyis is about 100 µg/cm
3.2 Spectral Interferences and Spectral Overlap. Spectral interference occurs when the entirety of the analyte spectral lines of two species are nearly 100% overlapped. The presence of arsenic (As) is a problematic interference for EDXRF systems which use the Pb L
3.3 Particle Size Effects and Attenuation Correction Factors. X-ray attenuation is dependent on the X-ray energy, mass sample loading, composition, and particle size. In some cases, the excitation and fluorescent X-rays are attenuated as they pass through the sample. In order to relate the measured intensity of the X-rays to the thin-film calibration standards used, the magnitude of any attenuation present must be corrected for. See references 6, 7, and 8 for more discussion on this issue. Essentially no attenuation corrections are necessary for Pb in PM
4. Precision
4.1 Measurement system precision is assessed according to the procedures set forth in appendix A to part 58. Measurement method precision is assessed from collocated sampling and analysis. The goal for acceptable measurement uncertainty, as precision, is defined as an upper 90 percent confidence limit for the coefficient of variation (CV) of 20 percent.
5. Bias
5.1 Measurement system bias for monitoring data is assessed according to the procedures set forth in appendix A of part 58. The bias is assessed through an audit using spiked filters. The goal for measurement bias is defined as an upper 95 percent confidence limit for the absolute bias of 15 percent.
6. Measurement of PTFE Filters by EDXRF
6.1 Sampling
6.1.1 Low-Volume PM
6.1.2 PTFE Filters and Filter Acceptance Testing. The PTFE filters used for PM
6.1.2.1 Filter Blanks. Field blank filters shall be collected along with routine samples. Field blank filters will be collected that are transported to the sampling site and placed in the sampler for the duration of sampling without sampling. Laboratory blank filters from each filter lot used shall be analyzed with each batch of routine sample filters analyzed. Laboratory blank filters are used in background subtraction as discussed below in Section 6.2.4.
6.2 Analysis. The four main categories of random and systematic error encountered in X-ray fluorescence analysis include errors from sample collection, the X-ray source, the counting process, and inter-element effects. These errors are addressed through the calibration process and mathematical corrections in the instrument software. Spectral processing methods are well established and most commercial analyzers have software that can implement the most common approaches (references 9–11) to background subtraction, peak overlap correction, counting and deadtime corrections.
6.2.1 EDXRF Analysis Instrument. An energy-dispersive XRF system is used. Energy-dispersive XRF systems are available from a number of commercial vendors. Examples include Thermo (www.thermo.com), Spectro (http://www.spectro.com), Xenemetrix (http://www.xenemetrix.com) and PANalytical (http://www.panalytical.com).
6.2.2 Thin film standards. Thin film standards are used for calibration because they most closely resemble the layer of particles on a filter. Thin films standards are typically deposited on Nuclepore substrates. The preparation of thin film standards is discussed in reference 8, and 10. The NIST SRM 2783 (Air Particulate on Filter Media) is currently available on polycarbonate filters and contains a certified concentration for Pb. Thin film standards at 15 and 50 µg/cm
6.2.3 Filter Preparation. Filters used for sample collection are 46.2-mm PTFE filters with a pore size of 2 microns and filter deposit area 11.86 cm
6.2.4 Calibration. In general, calibration determines each element’s sensitivity, i.e., its response in x-ray counts/sec to each µg/cm
6.2.4.1 Spectral Peak Fitting. The EPA uses a library of pure element peak shapes (shape standards) to extract the elemental background-free peak areas from an unknown spectrum. It is also possible to fit spectra using peak stripping or analytically defined functions such as modified Gaussian functions. The EPA shape standards are generated from pure, mono-elemental thin film standards. The shape standards are acquired for sufficiently long times to provide a large number of counts in the peaks of interest. It is not necessary for the concentration of the standard to be known. A slight contaminant in the region of interest in a shape standard can have a significant and serious effect on the ability of the least squares fitting algorithm to fit the shapes to the unknown spectrum. It is these elemental peak shapes that are fitted to the peaks in an unknown sample during spectral processing by the analyzer. In addition to this library of elemental shapes there is also a background shape spectrum for the filter type used as discussed below in section 6.2.4.2 of this section.
6.2.4.2 Background Measurement and Correction. A background spectrum generated by the filter itself must be subtracted from the X-ray spectrum prior to extracting peak areas. Background spectra must be obtained for each filter lot used for sample collection. The background shape standards which are used for background fitting are created at the time of calibration. If a new lot of filters is used, new background spectra must be obtained. A minimum of 20 clean blank filters from each filter lot are kept in a sealed container and are used exclusively for background measurement and correction. The spectra acquired on individual blank filters are added together to produce a single spectrum for each of the secondary targets or fluorescers used in the analysis of lead. Individual blank filter spectra which show atypical contamination are excluded from the summed spectra. The summed spectra are fitted to the appropriate background during spectral processing. Background correction is automatically included during spectral processing of each sample.
7. Calculation.
7.1 PM
7.2 PM
The principal contributors to total uncertainty of XRF values include: field sampling; filter deposit area; XRF calibration; attenuation or loss of the x-ray signals due to the other components of the particulate sample; and determination of the Pb X-ray emission peak area by curve fitting. See reference 12 for a detailed discussion of how uncertainties are similarly calculated for the PM
The model for calculating total uncertainty is:
8. References
1. Inorganic Compendium Method IO–3.3; Determination of Metals in Ambient Particulate Matter Using X-Ray Fluorescence (XRF) Spectroscopy; U.S. Environmental Protection Agency, Cincinnati, OH 45268. EPA/625/R–96/010a. June 1999.
2. Jenkins, R., Gould, R.W., and Gedcke, D. Quantitative X-ray Spectrometry: Second Edition. Marcel Dekker, Inc., New York, NY. 1995.
3. Jenkins, R. X-Ray Fluorescence Spectrometry: Second Edition in Chemical Analysis, a Series of Monographs on Analytical Chemistry and Its Applications, Volume 152. Editor J.D.Winefordner; John Wiley & Sons, Inc., New York, NY. 1999.
4. Dzubay, T.G. X-ray Fluorescence Analysis of Environmental Samples, Ann Arbor Science Publishers Inc., 1977.
5. Code of Federal Regulations (CFR) 40, Part 136, Appendix B; Definition and Procedure for the Determination of the Method Detection Limit—Revision 1.1.
6. Drane, E.A, Rickel, D.G., and Courtney, W.J., “Computer Code for Analysis X-Ray Fluorescence Spectra of Airborne Particulate Matter,” in Advances in X-Ray Analysis, J.R. Rhodes, Ed., Plenum Publishing Corporation, New York, NY, p. 23 (1980).
7. Analysis of Energy-Dispersive X-ray Spectra of Ambient Aerosols with Shapes Optimization, Guidance Document; TR–WDE–06–02; prepared under contract EP–D–05–065 for the U.S. Environmental Protection Agency, National Exposure Research Laboratory. March 2006.
8. Billiet, J., Dams, R., and Hoste, J. (1980) Multielement Thin Film Standards for XRF Analysis, X-Ray Spectrometry, 9(4): 206–211.
9. Bonner, N.A.; Bazan, F.; and Camp, D.C. (1973). Elemental analysis of air filter samples using x-ray fluorescence. Report No. UCRL–51388. Prepared for U.S. Atomic Energy Commission, by Univ. of Calif., Lawrence Livermore Laboratory, Livermore, CA.
10. Dzubay, T.G.; Lamothe, P.J.; and Yoshuda, H. (1977). Polymer films as calibration standards for X-ray fluorescence analysis. Adv. X-Ray Anal., 20:411.
11. Giauque, R.D.; Garrett, R.B.; and Goda, L.Y. (1977). Calibration of energy-dispersive X-ray spectrometers for analysis of thin environmental samples. In X-Ray Fluorescence Analysis of Environmental Samples, T.G. Dzubay, Ed., Ann Arbor Science Publishers, Ann Arbor, MI, pp. 153–181.
12. Harmonization of Interlaboratory X-ray Fluorescence Measurement Uncertainties, Detailed Discussion Paper; August 4, 2006; prepared for the Office of Air Quality Planning and Standards under EPA contract 68–D–03–038. http://www.epa.gov/ttn/amtic/files/ambient/pm25/spec/xrfdet.pdf.
Appendix R to Part 50—Interpretation of the National Ambient Air Quality Standards for Lead
(a) This appendix explains the data handling conventions and computations necessary for determining when the primary and secondary national ambient air quality standards (NAAQS) for lead (Pb) specified in § 50.16 are met. The NAAQS indicator for Pb is defined as: lead and its compounds, measured as elemental lead in total suspended particulate (Pb-TSP), sampled and analyzed by a Federal reference method (FRM) based on appendix G to this part or by a Federal equivalent method (FEM) designated in accordance with part 53 of this chapter. Although Pb-TSP is the lead NAAQS indicator, surrogate Pb-TSP concentrations shall also be used for NAAQS comparisons; specifically, valid surrogate Pb-TSP data are concentration data for lead and its compounds, measured as elemental lead, in particles with an aerodynamic size of 10 microns or less (Pb-PM
(b) Whether to exclude, retain, or make adjustments to the data affected by exceptional events, including natural events, is determined by the requirements and process deadlines specified in §§ 50.1, 50.14, and 51.930 of this chapter.
(c) The terms used in this appendix are defined as follows:
Annual monitoring network plan refers to the plan required by section 58.10 of this chapter.
Creditable samples are samples that are given credit for data completeness. They include valid samples collected on required sampling days and valid “make-up” samples taken for missed or invalidated samples on required sampling days.
Daily values for Pb refer to the 24-hour mean concentrations of Pb (Pb-TSP or Pb-PM
Design value is the site-level metric (i.e., statistic) that is compared to the NAAQS level to determine compliance; the design value for the Pb NAAQS is selected according to the procedures in this appendix from among the valid three-month Pb-TSP and surrogate Pb-TSP (Pb-PM
Extra samples are non-creditable samples. They are daily values that do not occur on scheduled sampling days and that can not be used as “make-up samples” for missed or invalidated scheduled samples. Extra samples are used in mean calculations. For purposes of determining whether a sample must be treated as a make-up sample or an extra sample, Pb-TSP and Pb-PM
Make-up samples are samples taken to replace missed or invalidated required scheduled samples. Make-ups can be made by either the primary or collocated (same size fraction) instruments; to be considered a valid make-up, the sampling must be conducted with equipment and procedures that meet the requirements for scheduled sampling. Make-up samples are either taken before the next required sampling day or exactly one week after the missed (or voided) sampling day. Make-up samples can not span years; that is, if a scheduled sample for December is missed (or voided), it can not be made up in January. Make-up samples, however, may span months, for example a missed sample on January 31 may be made up on February 1, 2, 3, 4, 5, or 7 (with an assumed sampling frequency of every sixth day). Section 3(e) explains how such month-spanning make-up samples are to be treated for purposes of data completeness and mean calculations. Only two make-up samples are permitted each calendar month; these are counted according to the month in which the miss and not the makeup occurred. For purposes of determining whether a sample must be treated as a make-up sample or an extra sample, Pb-TSP and Pb-PM
Monthly mean refers to an arithmetic mean, calculated as specified in section 6(a) of this appendix. Monthly means are computed at each monitoring site separately for Pb-TSP and Pb-PM
Parameter refers either to Pb-TSP or to Pb-PM
Pollutant Occurrence Code (POC) refers to a numerical code (1, 2, 3, etc.) used to distinguish the data from two or more monitors for the same parameter at a single monitoring site.
Scheduled sampling day means a day on which sampling is scheduled based on the required sampling frequency for the monitoring site, as provided in section 58.12 of this chapter.
Three-month means are arithmetic averages of three consecutive monthly means. Three-month means are computed on a rolling, overlapping basis. Each distinct monthly mean will be included in three different 3-month means; for example, in a given year, a November mean would be included in: (1) The September-October-November 3-month mean, (2) the October-November-December 3-month mean, and (3) the November-December-January(of the following year) 3-month mean. Three-month means are computed separately for each parameter per section 6(a) (and are referred to as 3-month parameter means) and are validated according to the criteria specified in section 4(c). The parameter-specific 3-month means are then prioritized according to section 2(a) to determine a single 3-month site mean.
Year refers to a calendar year.
2. Use of Pb-PM
(a) As stipulated in section 2.10 of Appendix C to 40 CFR part 58, at some mandatory Pb monitoring locations, monitoring agencies are required to sample for Pb as Pb-TSP, and at other mandatory Pb monitoring sites, monitoring agencies are permitted to monitor for Pb-PM
(i) Whenever a valid 3-month Pb-PM
(ii) Otherwise (i.e., there is no valid violating 3-month Pb-PM
(A) If a valid 3-month Pb-TSP mean exists, then it will be the site-level mean for that (site’s) 3-month period, or
(B) If a valid 3-month Pb-TSP mean does not exist, then there is no valid 3-month site mean for that period (even if a valid non-violating 3-month Pb-PM
(b) As noted in section 1(a) of this appendix, FRM/FEM Pb-PM
3. Requirements for Data Used for Comparisons With the Pb NAAQS and Data Reporting Considerations.
(a) All valid FRM/FEM Pb-TSP data and all valid FRM/FEM Pb-PM
(b) Pb-TSP and Pb-PM
(c) At each monitoring location (site), Pb-TSP and Pb-PM
(d) Daily values for sites will be selected for a site on a size cut (Pb-TSP or Pb-PM
(i) The starting dataset for a site-parameter shall consist of the measured daily concentrations recorded from the designated primary FRM/FEM monitor for that parameter. The primary monitor for each parameter shall be designated in the appropriate state or local agency annual Monitoring Network Plan. If no primary monitor is designated, the Administrator will select which monitor to treat as primary. All daily values produced by the primary sampler are considered part of the site-parameter data record (i.e., that site-parameter’s set of daily values); this includes all creditable samples and all extra samples. For pre-rule Pb-TSP and Pb-PM
(ii) Data for the primary monitor for each parameter shall be augmented as much as possible with data from collocated (same parameter) FRM/FEM monitors. If a valid 24-hour measurement is not produced from the primary monitor for a particular day (scheduled or otherwise), but a valid sample is generated by a collocated (same parameter) FRM/FEM instrument, then that collocated value shall be considered part of the site-parameter data record (i.e., that site-parameter’s monthly set of daily values). If more than one valid collocated FRM/FEM value is available, the mean of those valid collocated values shall be used as the daily value. Note that this step will not be necessary for pre-rule data given the daily identification presumption for the primary monitor.
(e) All daily values in the composite site-parameter record are used in monthly mean calculations. However, not all daily values are given credit towards data completeness requirements. Only “creditable” samples are given credit for data completeness. Creditable samples include valid samples on scheduled sampling days and valid make-up samples. All other types of daily values are referred to as “extra” samples. Make-up samples taken in the (first week of the) month after the one in which the miss/void occurred will be credited for data capture in the month of the miss/void but will be included in the month actually taken when computing monthly means. For example, if a make-up sample was taken in February to replace a missed sample scheduled for January, the make-up concentration would be included in the February monthly mean but the sample credited in the January data capture rate.
4. Comparisons With the Pb NAAQS.
(a) The Pb NAAQS is met at a monitoring site when the identified design value is valid and less than or equal to 0.15 micrograms per cubic meter (µg/m
(b) The Pb NAAQS is violated at a monitoring site when the identified design value is valid and is greater than 0.15 µg/m
(c)(i) A 3-month parameter mean is considered valid (i.e., meets data completeness requirements) if the average of the data capture rate of the three constituent monthly means (i.e., the 3-month data capture rate) is greater than or equal to 75 percent. Monthly data capture rates (expressed as a percentage) are specifically calculated as the number of creditable samples for the month (including any make-up samples taken the subsequent month for missed samples in the month in question, and excluding any make-up samples taken in the month in question for missed samples in the previous month) divided by the number of scheduled samples for the month, the result then multiplied by 100 but not rounded. The 3-month data capture rate is the sum of the three corresponding unrounded monthly data capture rates divided by three and the result rounded to the nearest integer (zero decimal places). As noted in section 3(c), Pb-TSP and Pb-PM
(ii) A 3-month parameter mean that does not have at least 75 percent data capture and thus is not considered valid under 4(c)(i) shall be considered valid (and complete) if it passes either of the two following “data substitution” tests, one such test for validating an above NAAQS-level (i.e., violating) 3-month Pb-TSP or Pb-PM
(A) The “above NAAQS level” test is as follows: Data substitution will be done in each month of the 3-month period that has less than 75 percent data capture; monthly capture rates are temporarily rounded to integers (zero decimals) for this evaluation. If by substituting the lowest reported daily value for that month (year non-specific; e.g., for January) over the 38-month design value period in question for missing scheduled data in the deficient months (substituting only enough to meet the 75 percent data capture minimum), the computation yields a recalculated test 3-month parameter mean concentration above the level of the standard, then the 3-month period is deemed to have passed the diagnostic test and the level of the standard is deemed to have been exceeded in that 3-month period. As noted in section 4(c)(ii), in such a case, the 3-month parameter mean of the data actually reported, not the recalculated (“test”) result including the low values, shall be used to determine the design value.
(B) The “below NAAQS level” test is as follows: Data substitution will be performed for each month of the 3-month period that has less than 75 percent but at least 50 percent data capture; if any month has less than 50% data capture then the 3-month mean can not utilize this substitution test. Also, incomplete 3-month Pb-PM
(d) Months that do not meet the completeness criteria stated in 4(c)(i) or 4(c)(ii), and design values that do not meet the completeness criteria stated in 4(a) or 4(b), may also be considered valid (and complete) with the approval of, or at the initiative of, the Administrator, who may consider factors such as monitoring site closures/moves, monitoring diligence, the consistency and levels of the valid concentration measurements that are available, and nearby concentrations in determining whether to use such data.
(e) The site-level design value for a 38-month period (three calendar years plus two previous months) is identified from the available (between one and 36) valid 3-month site means. In a situation where there are valid 3-month means for both parameters (Pb-TSP and Pb-PM
(f) The procedures for calculating monthly means and 3-month means, and identifying Pb design values are given in section 6 of this appendix.
5. Rounding Conventions.
(a) Monthly means and monthly data capture rates are not rounded.
(b) Three-month means shall be rounded to the nearest hundredth µg/m
(c) Because a Pb design value is simply a (highest) 3-month mean and because the NAAQS level is stated to two decimal places, no additional rounding beyond what is specified for 3-month means is required before a design value is compared to the NAAQS.
6. Procedures and Equations for the Pb NAAQS.
(a)(i) A monthly mean value for Pb-TSP (or Pb-PM
(a)(ii) The Administrator may at his discretion use the following alternate approach to calculating the monthly mean concentration if the number of extra sampling days during a month is greater than the number of successfully completed scheduled and make-up sample days in that month. In exercising his discretion, the Administrator will consider whether the approach specified in 6(a)(i) might in the Administrator’s judgment result in an unrepresentative value for the monthly mean concentration. This provision is to protect the integrity of the monthly and 3-month mean concentration values in situations in which, by intention or otherwise, extra sampling days are concentrated in a period during which ambient concentrations are particularly high or low. The alternate approach is to average all extra and make-up samples (in the given month) taken after each scheduled sampling day (“Day X”) and before the next scheduled sampling day (e.g., “Day X + 6”, in the case of one-in-six sampling) with the sample taken on Day X (assuming valid data was obtained on the scheduled sampling day), and then averaging these averages to calculate the monthly mean. This approach has the effect of giving approximately equal weight to periods during a month that have equal number of days, regardless of how many samples were actually obtained during the periods, thus mitigating the potential for the monthly mean to be distorted. The first day of scheduled sampling typically will not fall on the first day of the calendar month, and there may be make-up and/or extra samples (in that same calendar month) preceding the first scheduled day of the month. These samples will not be shifted into the previous month’s mean concentration, but rather will stay associated with their actual calendar month as follows. Any extra and make-up samples taken in a month before the first scheduled sampling day of the month will be associated with and averaged with the last scheduled sampling day of that same month.
(b) Three-month parameter means are determined by averaging three consecutive monthly means of the same parameter using Equation 2 of this appendix.
(c) Three-month site means are determined from available 3-month parameter means according to the hierarchy established in 2(a) of this appendix.
(d) The site-level Pb design value is the highest valid 3-month site-level mean over the most recent 38-month period (i.e., the most recent 3-year calendar period plus two previous months). Section 4(a) of this appendix explains when the identified design value is itself considered valid for purposes of determining that the NAAQS is met or violated at a site.
Appendix S to Part 50—Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide)
(a) This appendix explains the data handling conventions and computations necessary for determining when the primary national ambient air quality standards for oxides of nitrogen as measured by nitrogen dioxide (“NO
(b) Whether to exclude, retain, or make adjustments to the data affected by exceptional events, including natural events, is determined by the requirements and process deadlines specified in 50.1, 50.14 and 51.930 of this chapter.
(c) The terms used in this appendix are defined as follows:
Annual mean refers to the annual average of all of the 1-hour concentration values as defined in section 5.1 of this appendix.
Daily maximum 1-hour values for NO
Design values are the metrics (i.e., statistics) that are compared to the NAAQS levels to determine compliance, calculated as specified in section 5 of this appendix. The design values for the primary NAAQS are:
(1) The annual mean value for a monitoring site for one year (referred to as the “annual primary standard design value”).
(2) The 3-year average of annual 98th percentile daily maximum 1-hour values for a monitoring site (referred to as the “1-hour primary standard design value”).
98th percentile daily maximum 1-hour value is the value below which nominally 98 percent of all daily maximum 1-hour concentration values fall, using the ranking and selection method specified in section 5.2 of this appendix.
Quarter refers to a calendar quarter.
Year refers to a calendar year.
(a) All valid FRM/FEM NO
(b) When two or more NO
(c) Hourly NO
(a) The annual primary NO
(b) An annual primary standard design value is valid when at least 75 percent of the hours in the year are reported.
(c) An annual primary standard design value based on data that do not meet the completeness criteria stated in section 3.1(b) may also be considered valid with the approval of, or at the initiative of, the Administrator, who may consider factors such as monitoring site closures/moves, monitoring diligence, the consistency and levels of the valid concentration measurements that are available, and nearby concentrations in determining whether to use such data.
(d) The procedures for calculating the annual primary standard design values are given in section 5.1 of this appendix.
(a) The 1-hour primary NO
(b) An NO
(c) In the case of one, two, or three years that do not meet the completeness requirements of section 3.2(b) of this appendix and thus would normally not be useable for the calculation of a valid 3-year 1-hour primary standard design value, the 3-year 1-hour primary standard design value shall nevertheless be considered valid if one of the following conditions is true.
(i) At least 75 percent of the days in each quarter of each of three consecutive years have at least one reported hourly value, and the design value calculated according to the procedures specified in section 5.2 is above the level of the primary 1-hour standard.
(ii)(A) A 1-hour primary standard design value that is below the level of the NAAQS can be validated if the substitution test in section 3.2(c)(ii)(B) results in a “test design value” that is below the level of the NAAQS. The test substitutes actual “high” reported daily maximum 1-hour values from the same site at about the same time of the year (specifically, in the same calendar quarter) for unknown values that were not successfully measured. Note that the test is merely diagnostic in nature, intended to confirm that there is a very high likelihood that the original design value (the one with less than 75 percent data capture of hours by day and of days by quarter) reflects the true under-NAAQS-level status for that 3-year period; the result of this data substitution test (the “test design value”, as defined in section 3.2(c)(ii)(B)) is not considered the actual design value. For this test, substitution is permitted only if there are at least 200 days across the three matching quarters of the three years under consideration (which is about 75 percent of all possible daily values in those three quarters) for which 75 percent of the hours in the day, including State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator, have reported concentrations. However, maximum 1-hour values from days with less than 75 percent of the hours reported shall also be considered in identifying the high value to be used for substitution.
(B) The substitution test is as follows: Data substitution will be performed in all quarter periods that have less than 75 percent data capture but at least 50 percent data capture, including State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator; if any quarter has less than 50 percent data capture then this substitution test cannot be used. Identify for each quarter (e.g., January–March) the highest reported daily maximum 1-hour value for that quarter, excluding State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator, looking across those three months of all three years under consideration. All daily maximum 1-hour values from all days in the quarter period shall be considered when identifying this highest value, including days with less than 75 percent data capture. If after substituting the highest non-excluded reported daily maximum 1-hour value for a quarter for as much of the missing daily data in the matching deficient quarter(s) as is needed to make them 100 percent complete, the procedure in section 5.2 yields a recalculated 3-year 1-hour standard “test design value” below the level of the standard, then the 1-hour primary standard design value is deemed to have passed the diagnostic test and is valid, and the level of the standard is deemed to have been met in that 3-year period. As noted in section 3.2(c)(i), in such a case, the 3-year design value based on the data actually reported, not the “test design value”, shall be used as the valid design value.
(iii)(A) A 1-hour primary standard design value that is above the level of the NAAQS can be validated if the substitution test in section 3.2(c)(iii)(B) results in a “test design value” that is above the level of the NAAQS. The test substitutes actual “low” reported daily maximum 1-hour values from the same site at about the same time of the year (specifically, in the same three months of the calendar) for unknown values that were not successfully measured. Note that the test is merely diagnostic in nature, intended to confirm that there is a very high likelihood that the original design value (the one with less than 75 percent data capture of hours by day and of days by quarter) reflects the true above-NAAQS-level status for that 3-year period; the result of this data substitution test (the “test design value”, as defined in section 3.2(c)(iii)(B)) is not considered the actual design value. For this test, substitution is permitted only if there are a minimum number of available daily data points from which to identify the low quarter-specific daily maximum 1-hour values, specifically if there are at least 200 days across the three matching quarters of the three years under consideration (which is about 75 percent of all possible daily values in those three quarters) for which 75 percent of the hours in the day have reported concentrations. Only days with at least 75 percent of the hours reported shall be considered in identifying the low value to be used for substitution.
(B) The substitution test is as follows: Data substitution will be performed in all quarter periods that have less than 75 percent data capture. Identify for each quarter (e.g., January-March) the lowest reported daily maximum 1-hour value for that quarter, looking across those three months of all three years under consideration. All daily maximum 1-hour values from all days with at least 75 percent capture in the quarter period shall be considered when identifying this lowest value. If after substituting the lowest reported daily maximum 1-hour value for a quarter for as much of the missing daily data in the matching deficient quarter(s) as is needed to make them 75 percent complete, the procedure in section 5.2 yields a recalculated 3-year 1-hour standard “test design value” above the level of the standard, then the 1-hour primary standard design value is deemed to have passed the diagnostic test and is valid, and the level of the standard is deemed to have been exceeded in that 3-year period. As noted in section 3.2(c)(i), in such a case, the 3-year design value based on the data actually reported, not the “test design value”, shall be used as the valid design value.
(d) A 1-hour primary standard design value based on data that do not meet the completeness criteria stated in 3.2(b) and also do not satisfy section 3.2(c), may also be considered valid with the approval of, or at the initiative of, the Administrator, who may consider factors such as monitoring site closures/moves, monitoring diligence, the consistency and levels of the valid concentration measurements that are available, and nearby concentrations in determining whether to use such data.
(e) The procedures for calculating the 1-hour primary standard design values are given in section 5.2 of this appendix.
(a) Hourly NO
(b) The annual primary standard design value is calculated pursuant to section 5.1 and then rounded to the nearest whole number or 1 ppb (decimals 0.5 and greater are rounded up to the nearest whole number, and any decimal lower than 0.5 is rounded down to the nearest whole number).
(a) Hourly NO
(b) Daily maximum 1-hour values are not rounded.
(c) The 1-hour primary standard design value is calculated pursuant to section 5.2 and then rounded to the nearest whole number or 1 ppb (decimals 0.5 and greater are rounded up to the nearest whole number, and any decimal lower than 0.5 is rounded down to the nearest whole number).
(a) When the data for a site and year meet the data completeness requirements in section 3.1(b) of this appendix, or if the Administrator exercises the discretionary authority in section 3.1(c), the annual mean is simply the arithmetic average of all of the reported 1-hour values.
(b) The annual primary standard design value for a site is the valid annual mean rounded according to the conventions in section 4.1.
(a) Procedure for identifying annual 98th percentile values. When the data for a particular site and year meet the data completeness requirements in section 3.2(b), or if one of the conditions of section 3.2(c) is met, or if the Administrator exercises the discretionary authority in section 3.2(d), identification of annual 98th percentile value is accomplished as follows.
(i) The annual 98th percentile value for a year is the higher of the two values resulting from the following two procedures.
(1) Procedure 1.
(A) For the year, determine the number of days with at least 75 percent of the hourly values reported including State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator.
(B) For the year, from only the days with at least 75 percent of the hourly values reported, select from each day the maximum hourly value excluding State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator.
(C) Sort all these daily maximum hourly values from a particular site and year by descending value. (For example: (x[1], x[2], x[3], * * *, x[n]). In this case, x[1] is the largest number and x[n] is the smallest value.) The 98th percentile is determined from this sorted series of daily values which is ordered from the highest to the lowest number. Using the left column of Table 1, determine the appropriate range (i.e., row) for the annual number of days with valid data for year y (cn
(2) Procedure 2.
(A) For the year, determine the number of days with at least one hourly value reported including State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator.
(B) For the year, from all the days with at least one hourly value reported, select from each day the maximum hourly value excluding State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator.
(C) Sort all these daily maximum values from a particular site and year by descending value. (For example: (x[1], x[2], x[3], * * *, x[n]). In this case, x[1] is the largest number and x[n] is the smallest value.) The 98th percentile is determined from this sorted series of daily values which is ordered from the highest to the lowest number. Using the left column of Table 1, determine the appropriate range (i.e., row) for the annual number of days with valid data for year y (cn
(b) The 1-hour primary standard design value for a site is mean of the three annual 98th percentile values, rounded according to the conventions in section 4.
Table 1
Annual number of days with valid data for year “y” (cn | P nth maximum value of the year, where n is the listed number |
---|---|
1–50 | 1 |
51–100 | 2 |
101–150 | 3 |
151–200 | 4 |
201–250 | 5 |
251–300 | 6 |
301–350 | 7 |
351–366 | 8 |
Appendix T to Part 50—Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide)
(a) This appendix explains the data handling conventions and computations necessary for determining when the primary national ambient air quality standards for Oxides of Sulfur as measured by Sulfur Dioxide (“SO
(b) Decisions to exclude, retain, or make adjustments to the data affected by exceptional events, including natural events, are made according to the requirements and process deadlines specified in §§ 50.1, 50.14 and 51.930 of this chapter.
(c) The terms used in this appendix are defined as follows:
Daily maximum 1-hour values for SO
Design values are the metrics (i.e., statistics) that are compared to the NAAQS levels to determine compliance, calculated as specified in section 5 of this appendix. The design value for the primary 1-hour NAAQS is the 3-year average of annual 99th percentile daily maximum 1-hour values for a monitoring site (referred to as the “1-hour primary standard design value”).
99th percentile daily maximum 1-hour value is the value below which nominally 99 percent of all daily maximum 1-hour concentration values fall, using the ranking and selection method specified in section 5 of this appendix.
Pollutant Occurrence Code (POC) refers to a numerical code (1, 2, 3, etc.) used to distinguish the data from two or more monitors for the same parameter at a single monitoring site.
Quarter refers to a calendar quarter.
Year refers to a calendar year.
(a) All valid FRM/FEM SO
(b) Data from two or more monitors from the same year at the same site reported to EPA under distinct Pollutant Occurrence Codes shall not be combined in an attempt to meet data completeness requirements. The Administrator will combine annual 99th percentile daily maximum concentration values from different monitors in different years, selected as described here, for the purpose of developing a valid 1-hour primary standard design value. If more than one of the monitors meets the completeness requirement for all four quarters of a year, the steps specified in section 5(a) of this appendix shall be applied to the data from the monitor with the highest average of the four quarterly completeness values to derive a valid annual 99th percentile daily maximum concentration. If no monitor is complete for all four quarters in a year, the steps specified in section 3(c) and 5(a) of this appendix shall be applied to the data from the monitor with the highest average of the four quarterly completeness values in an attempt to derive a valid annual 99th percentile daily maximum concentration. This paragraph does not prohibit a monitoring agency from making a local designation of one physical monitor as the primary monitor for a Pollutant Occurrence Code and substituting the 1-hour data from a second physical monitor whenever a valid concentration value is not obtained from the primary monitor; if a monitoring agency substitutes data in this manner, each substituted value must be accompanied by an AQS qualifier code indicating that substitution with a value from a second physical monitor has taken place.
(c) Hourly SO
(a) The 1-hour primary SO
(b) An SO
(c) In the case of one, two, or three years that do not meet the completeness requirements of section 3(b) of this appendix and thus would normally not be useable for the calculation of a valid 3-year 1-hour primary standard design value, the 3-year 1-hour primary standard design value shall nevertheless be considered valid if one of the following conditions is true.
(i) At least 75 percent of the days in each quarter of each of three consecutive years have at least one reported hourly value, and the design value calculated according to the procedures specified in section 5 is above the level of the primary 1-hour standard.
(ii)(A) A 1-hour primary standard design value that is equal to or below the level of the NAAQS can be validated if the substitution test in section 3(c)(ii)(B) results in a “test design value” that is below the level of the NAAQS. The test substitutes actual “high” reported daily maximum 1-hour values from the same site at about the same time of the year (specifically, in the same calendar quarter) for unknown values that were not successfully measured. Note that the test is merely diagnostic in nature, intended to confirm that there is a very high likelihood that the original design value (the one with less than 75 percent data capture of hours by day and of days by quarter) reflects the true under-NAAQS-level status for that 3-year period; the result of this data substitution test (the “test design value”, as defined in section 3(c)(ii)(B)) is not considered the actual design value. For this test, substitution is permitted only if there are at least 200 days across the three matching quarters of the three years under consideration (which is about 75 percent of all possible daily values in those three quarters) for which 75 percent of the hours in the day, including State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator, have reported concentrations. However, maximum 1-hour values from days with less than 75 percent of the hours reported shall also be considered in identifying the high value to be used for substitution.
(B) The substitution test is as follows: Data substitution will be performed in all quarter periods that have less than 75 percent data capture but at least 50 percent data capture, including State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator; if any quarter has less than 50 percent data capture then this substitution test cannot be used. Identify for each quarter (e.g., January–March) the highest reported daily maximum 1-hour value for that quarter, excluding State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator, looking across those three months of all three years under consideration. All daily maximum 1-hour values from all days in the quarter period shall be considered when identifying this highest value, including days with less than 75 percent data capture. If after substituting the highest reported daily maximum 1-hour value for a quarter for as much of the missing daily data in the matching deficient quarter(s) as is needed to make them 100 percent complete, the procedure in section 5 yields a recalculated 3-year 1-hour standard “test design value” less than or equal to the level of the standard, then the 1-hour primary standard design value is deemed to have passed the diagnostic test and is valid, and the level of the standard is deemed to have been met in that 3-year period. As noted in section 3(c)(i), in such a case, the 3-year design value based on the data actually reported, not the “test design value”, shall be used as the valid design value.
(iii)(A) A 1-hour primary standard design value that is above the level of the NAAQS can be validated if the substitution test in section 3(c)(iii)(B) results in a “test design value” that is above the level of the NAAQS. The test substitutes actual “low” reported daily maximum 1-hour values from the same site at about the same time of the year (specifically, in the same three months of the calendar) for unknown hourly values that were not successfully measured. Note that the test is merely diagnostic in nature, intended to confirm that there is a very high likelihood that the original design value (the one with less than 75 percent data capture of hours by day and of days by quarter) reflects the true above-NAAQS-level status for that 3-year period; the result of this data substitution test (the “test design value”, as defined in section 3(c)(iii)(B)) is not considered the actual design value. For this test, substitution is permitted only if there are a minimum number of available daily data points from which to identify the low quarter-specific daily maximum 1-hour values, specifically if there are at least 200 days across the three matching quarters of the three years under consideration (which is about 75 percent of all possible daily values in those three quarters) for which 75 percent of the hours in the day have reported concentrations. Only days with at least 75 percent of the hours reported shall be considered in identifying the low value to be used for substitution.
(B) The substitution test is as follows: Data substitution will be performed in all quarter periods that have less than 75 percent data capture. Identify for each quarter (e.g., January–March) the lowest reported daily maximum 1-hour value for that quarter, looking across those three months of all three years under consideration. All daily maximum 1-hour values from all days with at least 75 percent capture in the quarter period shall be considered when identifying this lowest value. If after substituting the lowest reported daily maximum 1-hour value for a quarter for as much of the missing daily data in the matching deficient quarter(s) as is needed to make them 75 percent complete, the procedure in section 5 yields a recalculated 3-year 1-hour standard “test design value” above the level of the standard, then the 1-hour primary standard design value is deemed to have passed the diagnostic test and is valid, and the level of the standard is deemed to have been exceeded in that 3-year period. As noted in section 3(c)(i), in such a case, the 3-year design value based on the data actually reported, not the “test design value”, shall be used as the valid design value.
(d) A 1-hour primary standard design value based on data that do not meet the completeness criteria stated in 3(b) and also do not satisfy section 3(c), may also be considered valid with the approval of, or at the initiative of, the Administrator, who may consider factors such as monitoring site closures/moves, monitoring diligence, the consistency and levels of the valid concentration measurements that are available, and nearby concentrations in determining whether to use such data.
(e) The procedures for calculating the 1-hour primary standard design values are given in section 5 of this appendix.
(a) Hourly SO
(b) Daily maximum 1-hour values and therefore the annual 99th percentile of those daily values are not rounded.
(c) The 1-hour primary standard design value is calculated pursuant to section 5 and then rounded to the nearest whole number or 1 ppb (decimals 0.5 and greater are rounded up to the nearest whole number, and any decimal lower than 0.5 is rounded down to the nearest whole number).
(a) Procedure for identifying annual 99th percentile values. When the data for a particular ambient air quality monitoring site and year meet the data completeness requirements in section 3(b), or if one of the conditions of section 3(c) is met, or if the Administrator exercises the discretionary authority in section 3(d), identification of annual 99th percentile value is accomplished as follows.
(i) The annual 99th percentile value for a year is the higher of the two values resulting from the following two procedures.
(1) Procedure 1. For the year, determine the number of days with at least 75 percent of the hourly values reported.
(A) For the year, determine the number of days with at least 75 percent of the hourly values reported including State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator.
(B) For the year, from only the days with at least 75 percent of the hourly values reported, select from each day the maximum hourly value excluding State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator.
(C) Sort all these daily maximum hourly values from a particular site and year by descending value. (For example: (x[1], x[2], x[3], * * *, x[n]). In this case, x[1] is the largest number and x[n] is the smallest value.) The 99th percentile is determined from this sorted series of daily values which is ordered from the highest to the lowest number. Using the left column of Table 1, determine the appropriate range (i.e., row) for the annual number of days with valid data for year y (cn
(2) Procedure 2. For the year, determine the number of days with at least one hourly value reported.
(A) For the year, determine the number of days with at least one hourly value reported including State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator.
(B) For the year, from all the days with at least one hourly value reported, select from each day the maximum hourly value excluding State-flagged data affected by exceptional events which have been approved for exclusion by the Administrator.
(C) Sort all these daily maximum values from a particular site and year by descending value. (For example: (x[1], x[2], x[3], * * *, x[n]). In this case, x[1] is the largest number and x[n] is the smallest value.) The 99th percentile is determined from this sorted series of daily values which is ordered from the highest to the lowest number. Using the left column of Table 1, determine the appropriate range (i.e., row) for the annual number of days with valid data for year y (cn
(b) The 1-hour primary standard design value for an ambient air quality monitoring site is mean of the three annual 99th percentile values, rounded according to the conventions in section 4.
Table 1
Annual number of days with valid data for year “y” (cn | P maximum value of the year, where n is the listed number |
---|---|
1–100 | 1 |
101–200 | 2 |
201–300 | 3 |
301–366 | 4 |
Appendix U to Part 50—Interpretation of the Primary and Secondary National Ambient Air Quality Standards for Ozone
(a) This appendix explains the data handling conventions and computations necessary for determining whether the primary and secondary national ambient air quality standards (NAAQS) for ozone (O
(b) Whether to exclude or retain the data affected by exceptional events is determined by the requirements under §§ 50.1, 50.14 and 51.930.
(c) The terms used in this appendix are defined as follows:
8-hour average refers to the moving average of eight consecutive hourly O
Annual fourth-highest daily maximum refers to the fourth highest value measured at a site during a year.
Collocated monitors refers to the instance of two or more O
Daily maximum 8-hour average O
Design value refers to the metric (i.e., statistic) that is used to compare ambient O
Minimum data completeness requirements refer to the amount of data that a site is required to collect in order to make a valid determination that the site is meeting the NAAQS.
Monitor refers to a physical instrument used to measure ambient O
O
Site refers to an ambient O
Site data record refers to the set of hourly O
Year refers to calendar year.
(a) All valid hourly O
(b) All design value calculations shall be implemented on a site-level basis. If data are reported to EPA from collocated monitors, those data shall be combined into a single site data record as follows:
(i) The monitoring agency shall designate one monitor as the primary monitor for the site.
(ii) Hourly O
(c) In certain circumstances, including but not limited to site closures or relocations, data from two nearby sites may be combined into a single site data record for the purpose of calculating a valid design value. The appropriate Regional Administrator may approve such combinations after taking into consideration factors such as distance between sites, spatial and temporal patterns in air quality, local emissions and meteorology, jurisdictional boundaries, and terrain features.
(a) Hourly average O
(b) Moving 8-hour averages shall be computed from the hourly O
(c) The daily maximum 8-hour average O
(d) A daily maximum 8-hour average O
(e) The primary and secondary O
(a) The primary and secondary national ambient air quality standards for O
(b) A design value greater than the level of the NAAQS is always considered to be valid. A design value less than or equal to the level of the NAAQS must meet minimum data completeness requirements in order to be considered valid. These requirements are met for a 3-year period at a site if valid daily maximum 8-hour average O
(c) When computing whether the minimum data completeness requirements have been met, meteorological or ambient data may be sufficient to demonstrate that meteorological conditions on missing days were not conducive to concentrations above the level of the NAAQS. Missing days assumed less than the level of the NAAQS are counted for the purpose of meeting the minimum data completeness requirements, subject to the approval of the appropriate Regional Administrator.
(d) Comparisons with the primary and secondary O
Example 1—Site Meeting the Primary and Secondary O
Year | Percent valid days within O completeness) | 1st highest daily max 8-hour O (ppm) | 2nd highest daily max 8-hour O (ppm) | 3rd highest daily max 8-hour O (ppm) | 4th highest daily max 8-hour O (ppm) | 5th highest daily max 8-hour O (ppm) |
---|---|---|---|---|---|---|
2014 | 100 | 0.082 | 0.080 | 0.075 | 0.069 | 0.068 |
2015 | 96 | 0.074 | 0.073 | 0.065 | 0.062 | 0.060 |
2016 | 98 | 0.070 | 0.069 | 0.067 | 0.066 | 0.060 |
Average | 98 | 0.065 |
As shown in Example 1, this site meets the primary and secondary O
Example 2—Site Failing to Meet the Primary and Secondary O3 O
Year | Percent valid days within O | 1st highest daily max 8-hour O (ppm) | 2nd highest daily max 8-hour O (ppm) | 3rd highest daily max 8-hour O (ppm) | 4th highest daily max 8-hour O (ppm) | 5th highest daily max 8-hour O (ppm) |
---|---|---|---|---|---|---|
2014 | 96 | 0.085 | 0.080 | 0.079 | 0.074 | 0.072 |
2015 | 74 | 0.084 | 0.083 | 0.072 | 0.071 | 0.068 |
2016 | 98 | 0.083 | 0.081 | 0.081 | 0.075 | 0.074 |
Average | 89 | 0.073 |
As shown in Example 2, this site fails to meet the primary and secondary O
PART 51—REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS
Subpart A—Air Emissions Reporting Requirements
General Information for Inventory Preparers
§ 51.1 Who is responsible for actions described in this subpart?
States must inventory emission sources located on nontribal lands and report this information to EPA.
§ 51.5 What tools are available to help prepare and report emissions data?
(a) We urge your state to use estimation procedures described in documents from the Emission Inventory Improvement Program (EIIP), available at the following Internet address: http://www.epa.gov/ttn/chief/eiip. These procedures are standardized and ranked according to relative uncertainty for each emission estimating technique. Using this guidance will enable others to use your state’s data and evaluate its quality and consistency with other data.
(b) Where current EIIP guidance materials have been supplanted by state-of-the-art emission estimation approaches or are not applicable to sources or source categories, states are urged to use applicable, state-of-the-art techniques for estimating emissions.
§ 51.10 [Reserved]
Specific Reporting Requirements
§ 51.15 What data does my state need to report to EPA?
(a) Pollutants. Report actual emissions of the following (see § 51.50 for precise definitions as required):
(1) Required pollutants for triennial reports of annual (12-month) emissions for all sources and every-year reports of annual emissions from Type A sources:
(i) Sulfur dioxide (SO
(ii) Volatile organic compounds (VOC).
(iii) Nitrogen oxides (NO
(iv) Carbon monoxide (CO).
(v) Lead and lead compounds.
(vi) Primary PM
(vii) Primary PM
(viii) Ammonia (NH
(2) A state may, at its option, choose to report NO
(3) A state may, at its option, choose to report ozone season day emissions of NO
(4) A state may, at its option, include estimates of emissions for additional pollutants (such as hazardous air pollutants) in its emission inventory reports.
(b) Sources. Emissions should be reported from the following sources in all parts of the state, excluding sources located on tribal lands:
(1) Point.
(2) Nonpoint. States may choose to meet the requirements for some of their nonpoint sources by accepting the EPA’s estimates for the sources for which the EPA makes calculations. In such instances, states are encouraged to review and update the activity values or other calculational inputs used by the EPA for these sources.
(3) Onroad and Nonroad mobile. (i) Emissions for onroad and nonroad mobile sources must be reported as inputs to the latest EPA-developed mobile emissions models, such as the Motor Vehicle Emissions Simulator (MOVES) for onroad sources or the NMIM for nonroad sources. States using these models may report, at their discretion, emissions values computed from these models in addition to the model inputs.
(ii) In lieu of submitting model inputs for onroad and nonroad mobile sources, California must submit emissions values.
(iii) In lieu of submitting any data, states may accept existing EPA emission estimates.
(4) Emissions for wild and prescribed fires are not required to be reported by states. If states wish to optionally report these sources, they must be reported to the events data category. The events data category is a day-specific accounting of these large-scale but usually short duration emissions. Submissions must include both daily emissions estimates as well as daily acres burned values. In lieu of submitting this information, states may accept the EPA estimates or they may submit inputs (e.g., acres burned, fuel loads) for us to use in the EPA’s estimation approach.
(c) Supporting information. You must report the data elements in Tables 2a and 2b in Appendix A of this subpart. We may ask you for other data on a voluntary basis to meet special purposes.
(d) Confidential data. We do not consider the data in Tables 2a and 2b in Appendix A of this subpart confidential, but some states limit release of these types of data. Any data that you submit to EPA under this subpart will be considered in the public domain and cannot be treated as confidential. If Federal and state requirements are inconsistent, consult your EPA Regional Office for a final reconciliation.
§ 51.20 What are the emission thresholds that separate point and nonpoint sources?
(a) All anthropogenic stationary sources must be included in your inventory as either point or nonpoint sources.
(b) Sources that meet the definition of point source in this subpart must be reported as point sources. All pollutants specified in § 51.15(a) must be reported for point sources, not just the pollutant(s) that qualify the source as a point source.
(c) If your state has lower emission reporting thresholds for point sources than paragraph (b) of this section, then you may use these in reporting your emissions to EPA.
(d) All stationary source emissions that are not reported as point sources must be reported as nonpoint sources. Episodic wind-generated particulate matter (PM) emissions from sources that are not major sources may be excluded, for example dust lifted by high winds from natural or tilled soil. Emissions of nonpoint sources should be aggregated to the resolution required by the EIS as described in the current National Emission Inventory (NEI) inventory year plan posted at http://www.epa.gov/ttn/chief/eiinformation.html. In most cases, this is county level and must be separated and identified by source classification code (SCC). Nonpoint source categories or emission events reasonably estimated by the state to represent a de minimis percentage of total county and state emissions of a given pollutant may be omitted.
(1) The reporting of wild and prescribed fires is encouraged but not required and should be done via only the “Events” data category.
(2) Agricultural fires (also referred to as crop residue burning) must be reported to the nonpoint data category.
§ 51.25 What geographic area must my state’s inventory cover?
Because of the regional nature of these pollutants, your state’s inventory must be statewide, regardless of any area’s attainment status.
§ 51.30 When does my state report which emissions data to EPA?
All states are required to report two basic types of emission inventories to the EPA: An every-year inventory; and a triennial inventory.
(a) Every-year inventory. See Tables 2a and 2b of Appendix A of this subpart for the specific data elements to report every year.
(1) All states are required to report every year the annual (12-month) emissions data described in § 51.15 from Type A (large) point sources, as defined in Table 1 of Appendix A of this subpart. The first every-year cycle inventory will be for the 2009 inventory year and must be submitted to the EPA within 12 months, i.e., by December 31, 2010.
(2) In inventory years that fall under the triennial inventory requirements, the reporting required by the triennial inventory satisfies the every-year reporting requirements of paragraph (a) of this section.
(b) Triennial inventory. See Tables 2a and 2b to Appendix A of subpart A for the specific data elements that must be reported for the triennial inventories.
(1) All states are required to report for every third inventory year the annual (12-month) emissions data as described in § 51.15. The first triennial inventory will be for the 2011 inventory and must be submitted to the EPA within 12 months, i.e., by December 31, 2012. Subsequent triennial inventories (2014, 2017, etc.) will be due 12 months after the end of the inventory year, i.e., by December 31 of the following year.
(2) [Reserved]
§ 51.35 How can my state equalize the emission inventory effort from year to year?
(a) Compiling a triennial inventory means more effort every 3 years. As an option, your state may ease this workload spike by using the following approach:
(1) Each year, collect and report data for all Type A (large) point sources (this is required for all Type A point sources).
(2) Each year, collect data for one-third of your sources that are not Type A point sources. Collect data for a different third of these sources each year so that data has been collected for all of the sources that are not Type A point sources by the end of each 3-year cycle. You must save 3 years of data and then report all emissions from the sources that are not Type A point sources on the triennial inventory due date.
(3) Each year, collect data for one-third of the nonpoint, nonroad mobile, and onroad mobile sources. You must save 3 years of data for each such source and then report all of these data on the triennial inventory due date.
(b) For the sources described in paragraph (a) of this section, your state will have data from 3 successive years at any given time, rather than from the single year in which it is compiled.
(c) If your state chooses the method of inventorying one-third of your sources that are not Type A point sources and triennial inventory nonpoint, nonroad mobile, and onroad mobile sources each year, your state must compile each year of the 3-year period identically. For example, if a process has not changed for a source category or individual plant, your state must use the same emission factors to calculate emissions for each year of the 3-year period. If your state has revised emission factors during the 3 years for a process that has not changed, you must compute previous years’ data using the revised factor. If your state uses models to estimate emissions, you must make sure that the model is the same for all 3 years.
§ 51.40 In what form and format should my state report the data to EPA?
You must report your emission inventory data to us in electronic form. We support specific electronic data reporting formats, and you are required to report your data in a format consistent with these. The term “format” encompasses the definition of one or more specific data fields for each of the data elements listed in Tables 2a and 2b in Appendix A of this subpart; allowed code values for certain data fields; transmittal information; and data table relational structure. Because electronic reporting technology may change, contact the EPA Emission Inventory and Analysis Group (EIAG) for the latest specific formats. You can find information on the current formats at the following Internet address: http://www.epa.gov/ttn/chief/eis/2011nei/xml_data_eis.pdf. You may also call the air emissions contact in your EPA Regional Office or our Info CHIEF help desk at (919) 541–1000 or send email to [email protected].
§ 51.45 Where should my state report the data?
(a) Your state submits or reports data by providing it directly to EPA.
(b) The latest information on data reporting procedures is available at the following Internet address: http://www.epa.gov/ttn/chief. You may also call our Info CHIEF help desk at (919) 541–1000 or e-mail to [email protected].
§ 51.50 What definitions apply to this subpart?
Aircraft engine type means a code defining a unique combination of aircraft and engine used as an input parameter for calculating emissions from aircraft.
Annual emissions means actual emissions for a plant, point, or process that are measured or calculated to represent a calendar year.
Control measure means a unique code for the type of control device or operational measure (e.g., wet scrubber, flaring, process change, ban) used to reduce emissions.
Emission calculation method means the code describing how the emissions for a pollutant were calculated, e.g., by stack test, continuous emissions monitor, EPA emission factor, etc.
Emission factor means the ratio relating emissions of a specific pollutant to an activity throughput level.
Emission operating type means the operational status of an emissions unit for the time period for which emissions are being reported, i.e., Routine, Startup, Shutdown, or Upset.
Emission process identifier means a unique code for the process generating the emissions.
Emission type means the type of emissions produced for onroad and nonroad sources or the mode of operation for marine vessels.
Emissions year means the calendar year for which the emissions estimates are reported.
Facility site identifier means the unique code for a plant or facility treated as a point source, containing one or more pollutant-emitting units. The EPA’s reporting format allows for state submittals to use either the state’s data system identifiers or the EPA’s Emission Inventory System identifiers.
Facility site name means the name of the facility.
Lead (Pb) means lead as defined in 40 CFR 50.12. Emissions of Pb which occur either as elemental Pb or as a chemical compound containing Pb should be reported as the mass of the Pb atoms only.
Mobile source means a motor vehicle, nonroad engine or nonroad vehicle, where:
(1) A motor vehicle is any self-propelled vehicle used to carry people or property on a street or highway;
(2) A nonroad engine is an internal combustion engine (including fuel system) that is not used in a motor vehicle or a vehicle used solely for competition, or that is not affected by sections 111 or 202 of the CAA; and
(3) A nonroad vehicle is a vehicle that is run by a nonroad engine and that is not a motor vehicle or a vehicle used solely for competition.
NAICS means North American Industry Classification System code. The NAICS codes are U.S. Department of Commerce’s codes for categorizing businesses by products or services and have replaced Standard Industrial Classification codes.
Nitrogen oxides (NO
Nonpoint sources collectively represent individual sources that have not been inventoried as specific point or mobile sources. These individual sources treated collectively as nonpoint sources are typically too small, numerous, or difficult to inventory using the methods for the other classes of sources.
Particulate matter (PM) is a criteria air pollutant. For the purpose of this subpart, the following definitions apply:
(1) Filterable PM
(2) Condensable PM: Material that is vapor phase at stack conditions, but which condenses and/or reacts upon cooling and dilution in the ambient air to form solid or liquid PM immediately after discharge from the stack. Note that all condensable PM, if present from a source, is typically in the PM
(3) Primary PM
(4) Primary PM
(5) Secondary PM: Particles that form or grow in mass through chemical reactions in the ambient air well after dilution and condensation have occurred. Secondary PM is usually formed at some distance downwind from the source. Secondary PM should not be reported in the emission inventory and is not covered by this subpart.
Percent control approach capture efficiency means the percentage of an exhaust gas stream actually collected for routing to a set of control devices.
Percent control approach effectiveness means the percentage of time or activity throughput that a control approach is operating as designed, including the capture and reduction devices. This percentage accounts for the fact that controls typically are not 100 percent effective because of equipment downtime, upsets and decreases in control efficiencies.
Percent control approach penetration means the percentage of a nonpoint source category activity that is covered by the reported control measures.
Percent control measures reduction efficiency means the net emission reduction efficiency across all emissions control devices. It does not account for capture device efficiencies.
Physical address means the location address (street address or other physical location description), locality name, state, and postal zip code of a facility. This is the physical location where the emissions occur; not the corporate headquarters or a mailing address.
Point source means large, stationary (non-mobile), identifiable sources of emissions that release pollutants into the atmosphere. A point source is a facility that is a major source under 40 CFR part 70 for one or more of the pollutants for which reporting is required by § 51.15 (a)(1). This does not include the emissions of hazardous air pollutants, which are not considered in determining whether a source is a point source under this subpart. The minimum point source reporting thresholds are shown in Table 1 of Appendix A.
Pollutant code means a unique code for each reported pollutant assigned by the reporting format specified by the EPA for each inventory year.
Release point apportionment percent means the average percentage(s) of an emissions exhaust stream directed to a given release point.
Release point exit gas flow rate means the numeric value of the flow rate of a stack gas.
Release point exit gas temperature means the numeric value of the temperature of an exit gas stream in degrees Fahrenheit.
Release point exit gas velocity means the numeric value of the velocity of an exit gas stream.
Release point identifier means a unique code for the point where emissions from one or more processes release into the atmosphere.
Release point stack diameter means the inner physical diameter of a stack.
Release point stack height means physical height of a stack above the surrounding terrain.
Release point type code means the code for physical configuration of the release point.
Reporting period type means the code describing the time period covered by the emissions reported, i.e., Annual, 5-month ozone season, summer day, or winter.
Source classification code (SCC) means a process-level code that describes the equipment and/or operation which is emitting pollutants.
State and county FIPS code means the system of unique identifiers in the Federal Information Placement System (FIPS) used to identify states, counties and parishes for the entire United States, Puerto Rico, and Guam.
Throughput means a measurable factor or parameter that relates directly or indirectly to the emissions of an air pollution source during the period for which emissions are reported. Depending on the type of source category, activity information may refer to the amount of fuel combusted, raw material processed, product manufactured, or material handled or processed. It may also refer to population, employment, or number of units. Activity throughput is typically the value that is multiplied against an emission factor to generate an emissions estimate.
Type A source means large point sources with a potential to emit greater than or equal to any of the thresholds listed in Table 1 of Appendix A of this subpart. If a source is a Type A source for any pollutant listed in Table 1, then the emissions for all pollutants required by § 51.15 must be reported for that source.
Unit design capacity means a measure of the size of a point source, based on the reported maximum continuous throughput or output capacity of the unit.
Unit identifier means a unique code for the unit that generates emissions, typically a physical piece of equipment or a closely related set of equipment.
VOC means volatile organic compounds. The EPA’s regulatory definition of VOC is in 40 CFR 51.100.
Appendix A to Subpart A of Part 51—Tables
Table 1 to Appendix A of Subpart A—Emission Thresholds
1 by Pollutant for Treatment as Point Source Under 40 CFR 51.30
Pollutant | Every-year | Triennial | |
---|---|---|---|
Type A sources 2 | Type B sources | NAA sources 3 | |
(1) SO | ≥2500 | ≥100 | ≥100. |
PM | |||
(2) VOC | ≥250 | ≥100 | ≥100. |
within OTR 4 ≥50 | within OTR ≥50. | ||
O | |||
O | |||
O | |||
PM | |||
(3) NO | ≥2500 | ≥100 | ≥100. |
O | |||
O | |||
O | |||
PM | |||
(4) CO | ≥2500 | ≥1000 | ≥1000. |
CO (all areas) ≥100. | |||
(5) Lead | ≥0.5 (actual) | ≥0.5 (actual). | |
(6) Primary PM | ≥250 | ≥100 | ≥100. |
PM | |||
(7) Primary PM | ≥250 | ≥100 | ≥100. |
PM | |||
(8) NH | ≥250 | ≥100 | ≥100. |
PM |
1 Thresholds for point source determination shown in tons per year of potential to emit as defined in 40 CFR part 70, with the exception of lead. Reported emissions should be in actual tons emitted for the required time period.
2 Type A sources are a subset of the Type B sources and are the larger emitting sources by pollutant.
3 NAA = Nonattainment Area. The point source reporting thresholds vary by attainment status for SO
4 OTR = Ozone Transport Region (see 40 CFR 51.1300(k)).
Table 2
1 Data Elements for Reporting Emissions From Point Sources, Where Required by 40 CFR 51.30
Data elements |
---|
(1) Emissions Year. |
(2) State and County FIPS Code or Tribal Code. |
(3) Facility Site Identifier. |
(4) Unit Identifier. |
(5) Emission Process Identifier. |
(6) Release Point Identifier. |
(7) Facility Site Name. |
(8) Physical Address (Location Address, Locality Name, State and Postal Code). |
(9) Latitude and Longitude at facility level. |
(10) Source Classification Code. |
(11) Aircraft Engine Type (where applicable). |
(12) Facility Site Status and Year. |
(13) Release Point Stack Height and Unit of Measure. |
(14) Release Point Stack Diameter and Unit of Measure. |
(15) Release Point Exit Gas Temperature and Unit of Measure. |
(16) Release Point Exit Gas Velocity or Release Point Exit Gas Flow Rate and Unit of Measure. |
(17) Release Point Status and Year. |
(18) NAICS at facility level. |
(19) Unit Design Capacity and Unit of Measure (for some unit types). |
(20) Unit Type. |
(21) Unit Status and Year. |
(22) Release Point Apportionment Percent. |
(23) Release Point Type. |
(24) Control Measure and Control Pollutant (where applicable). |
(25) Percent Control Approach Capture Efficiency (where applicable). |
(26) Percent Control Measures Reduction Efficiency (where applicable). |
(27) Percent Control Approach Effectiveness (where applicable). |
1 Facility Inventory data elements need only be reported once to the EIS and then revised if needed. They do not need to be reported for each triennial or every-year emissions inventory.
Table 2
Data elements | Point | Nonpoint | Onroad | Nonroad |
---|---|---|---|---|
(1) Emissions Year | Y | Y | Y | Y |
(2) FIPS code | Y | Y | Y | Y |
(3) Shape Identifiers (where applicable) | Y | |||
(4) Source Classification Code | Y | Y | Y | |
(5) Emission Type (where applicable) | Y | Y | Y | |
(8) Emission Factor | Y | Y | ||
(9) Throughput (Value, Material, Unit of Measure, and Type) | Y | Y | Y | |
(10) Pollutant Code | Y | Y | Y | Y |
(11) Annual Emissions and Unit of Measure | Y | Y | Y | Y |
(12) Reporting Period Type (Annual) | Y | Y | Y | Y |
(13) Emission Operating Type (Routine) | Y | |||
(14) Emission Calculation Method | Y | Y | ||
(15) Control Measure and Control Pollutant (where applicable) | Y | |||
(16) Percent Control Measures Reduction Efficiency (where applicable) | Y | |||
(17) Percent Control Approach Effectiveness (where applicable) | Y | |||
(18) Percent Control Approach Penetration (where applicable) | Y |
Subparts B–E [Reserved]
Subpart F—Procedural Requirements
§ 51.100 Definitions.
As used in this part, all terms not defined herein will have the meaning given them in the Act:
(a) Act means the Clean Air Act (42 U.S.C. 7401 et seq., as amended by Pub. L. 91–604, 84 Stat. 1676 Pub. L. 95–95, 91 Stat., 685 and Pub. L. 95–190, 91 Stat., 1399.)
(b) Administrator means the Administrator of the Environmental Protection Agency (EPA) or an authorized representative.
(c) Primary standard means a national primary ambient air quality standard promulgated pursuant to section 109 of the Act.
(d) Secondary standard means a national secondary ambient air quality standard promulgated pursuant to section 109 of the Act.
(e) National standard means either a primary or secondary standard.
(f) Owner or operator means any person who owns, leases, operates, controls, or supervises a facility, building, structure, or installation which directly or indirectly result or may result in emissions of any air pollutant for which a national standard is in effect.
(g) Local agency means any local government agency other than the State agency, which is charged with responsibility for carrying out a portion of the plan.
(h) Regional Office means one of the ten (10) EPA Regional Offices.
(i) State agency means the air pollution control agency primarily responsible for development and implementation of a plan under the Act.
(j) Plan means an implementation plan approved or promulgated under section 110 of 172 of the Act.
(k) Point source means the following:
(1) For particulate matter, sulfur oxides, carbon monoxide, volatile organic compounds (VOC) and nitrogen dioxide—
(i) Any stationary source the actual emissions of which are in excess of 90.7 metric tons (100 tons) per year of the pollutant in a region containing an area whose 1980 urban place population, as defined by the U.S. Bureau of the Census, was equal to or greater than 1 million.
(ii) Any stationary source the actual emissions of which are in excess of 22.7 metric tons (25 tons) per year of the pollutant in a region containing an area whose 1980 urban place population, as defined by the U.S. Bureau of the Census, was less than 1 million; or
(2) For lead or lead compounds measured as elemental lead, any stationary source that actually emits a total of 4.5 metric tons (5 tons) per year or more.
(l) Area source means any small residential, governmental, institutional, commercial, or industrial fuel combustion operations; onsite solid waste disposal facility; motor vehicles, aircraft vessels, or other transportation facilities or other miscellaneous sources identified through inventory techniques similar to those described in the “AEROS Manual series, Vol. II AEROS User’s Manual,” EPA–450/2–76–029 December 1976.
(m) Region means an area designated as an air quality control region (AQCR) under section 107(c) of the Act.
(n) Control strategy means a combination of measures designated to achieve the aggregate reduction of emissions necessary for attainment and maintenance of national standards including, but not limited to, measures such as:
(1) Emission limitations.
(2) Federal or State emission charges or taxes or other economic incentives or disincentives.
(3) Closing or relocation of residential, commercial, or industrial facilities.
(4) Changes in schedules or methods of operation of commercial or industrial facilities or transportation systems, including, but not limited to, short-term changes made in accordance with standby plans.
(5) Periodic inspection and testing of motor vehicle emission control systems, at such time as the Administrator determines that such programs are feasible and practicable.
(6) Emission control measures applicable to in-use motor vehicles, including, but not limited to, measures such as mandatory maintenance, installation of emission control devices, and conversion to gaseous fuels.
(7) Any transportation control measure including those transportation measures listed in section 108(f) of the Clean Air Act as amended.
(8) Any variation of, or alternative to any measure delineated herein.
(9) Control or prohibition of a fuel or fuel additive used in motor vehicles, if such control or prohibition is necessary to achieve a national primary or secondary air quality standard and is approved by the Administrator under section 211(c)(4)(C) of the Act.
(o) Reasonably available control technology (RACT) means devices, systems, process modifications, or other apparatus or techniques that are reasonably available taking into account:
(1) The necessity of imposing such controls in order to attain and maintain a national ambient air quality standard;
(2) The social, environmental, and economic impact of such controls; and
(3) Alternative means of providing for attainment and maintenance of such standard. (This provision defines RACT for the purposes of § 51.341(b) only.)
(p) Compliance schedule means the date or dates by which a source or category of sources is required to comply with specific emission limitations contained in an implementation plan and with any increments of progress toward such compliance.
(q) Increments of progress means steps toward compliance which will be taken by a specific source, including:
(1) Date of submittal of the source’s final control plan to the appropriate air pollution control agency;
(2) Date by which contracts for emission control systems or process modifications will be awarded; or date by which orders will be issued for the purchase of component parts to accomplish emission control or process modification;
(3) Date of initiation of on-site construction or installation of emission control equipment or process change;
(4) Date by which on-site construction or installation of emission control equipment or process modification is to be completed; and
(5) Date by which final compliance is to be achieved.
(r) Transportation control measure means any measure that is directed toward reducing emissions of air pollutants from transportation sources. Such measures include, but are not limited to, those listed in section 108(f) of the Clean Air Act.
(s) Volatile organic compounds (VOC) means any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions.
(1) This includes any such organic compound other than the following, which have been determined to have negligible photochemical reactivity: methane; ethane; methylene chloride (dichloromethane); 1,1,1-trichloroethane (methyl chloroform); 1,1,2-trichloro-1,2,2-trifluoroethane (CFC–113); trichlorofluoromethane (CFC–11); dichlorodifluoromethane (CFC–12); chlorodifluoromethane (HCFC–22); trifluoromethane (HFC–23); 1,2-dichloro 1,1,2,2-tetrafluoroethane (CFC–114); chloropentafluoroethane (CFC–115); 1,1,1-trifluoro 2,2-dichloroethane (HCFC–123); 1,1,1,2-tetrafluoroethane (HFC–134a); 1,1-dichloro 1-fluoroethane (HCFC–141b); 1-chloro 1,1-difluoroethane (HCFC–142b); 2-chloro-1,1,1,2-tetrafluoroethane (HCFC–124); pentafluoroethane (HFC–125); 1,1,2,2-tetrafluoroethane (HFC–134); 1,1,1-trifluoroethane (HFC–143a); 1,1-difluoroethane (HFC–152a); parachlorobenzotrifluoride (PCBTF); cyclic, branched, or linear completely methylated siloxanes; acetone; perchloroethylene (tetrachloroethylene); 3,3-dichloro-1,1,1,2,2-pentafluoropropane (HCFC–225ca); 1,3-dichloro-1,1,2,2,3-pentafluoropropane (HCFC–225cb); 1,1,1,2,3,4,4,5,5,5-decafluoropentane (HFC 43–10mee); difluoromethane (HFC–32); ethylfluoride (HFC–161); 1,1,1,3,3,3-hexafluoropropane (HFC–236fa); 1,1,2,2,3-pentafluoropropane (HFC–245ca); 1,1,2,3,3-pentafluoropropane (HFC–245ea); 1,1,1,2,3-pentafluoropropane (HFC–245eb); 1,1,1,3,3-pentafluoropropane (HFC–245fa); 1,1,1,2,3,3-hexafluoropropane (HFC–236ea); 1,1,1,3,3-pentafluorobutane (HFC–365mfc); chlorofluoromethane (HCFC–31); 1 chloro-1-fluoroethane (HCFC–151a); 1,2-dichloro-1,1,2-trifluoroethane (HCFC–123a); 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane (C
(i) Cyclic, branched, or linear, completely fluorinated alkanes;
(ii) Cyclic, branched, or linear, completely fluorinated ethers with no unsaturations;
(iii) Cyclic, branched, or linear, completely fluorinated tertiary amines with no unsaturations; and
(iv) Sulfur containing perfluorocarbons with no unsaturations and with sulfur bonds only to carbon and fluorine.
(2) For purposes of determining compliance with emissions limits, VOC will be measured by the test methods in the approved State implementation plan (SIP) or 40 CFR part 60, appendix A, as applicable. Where such a method also measures compounds with negligible photochemical reactivity, these negligibility-reactive compounds may be excluded as VOC if the amount of such compounds is accurately quantified, and such exclusion is approved by the enforcement authority.
(3) As a precondition to excluding these compounds as VOC or at any time thereafter, the enforcement authority may require an owner or operator to provide monitoring or testing methods and results demonstrating, to the satisfaction of the enforcement authority, the amount of negligibly-reactive compounds in the source’s emissions.
(4) For purposes of Federal enforcement for a specific source, the EPA shall use the test methods specified in the applicable EPA-approved SIP, in a permit issued pursuant to a program approved or promulgated under title V of the Act, or under 40 CFR part 51, subpart I or appendix S, or under 40 CFR parts 52 or 60. The EPA shall not be bound by any State determination as to appropriate methods for testing or monitoring negligibly-reactive compounds if such determination is not reflected in any of the above provisions.
(5) [Reserved]
(6) For the purposes of determining compliance with California’s aerosol coatings reactivity-based regulation, (as described in the California Code of Regulations, Title 17, Division 3, Chapter 1, Subchapter 8.5, Article 3), any organic compound in the volatile portion of an aerosol coating is counted towards that product’s reactivity-based limit. Therefore, the compounds identified in paragraph (s) of this section as negligibly reactive and excluded from EPA’s definition of VOCs are to be counted towards a product’s reactivity limit for the purposes of determining compliance with California’s aerosol coatings reactivity-based regulation.
(7) For the purposes of determining compliance with EPA’s aerosol coatings reactivity based regulation (as described in 40 CFR part 59—National Volatile Organic Compound Emission Standards for Consumer and Commercial Products) any organic compound in the volatile portion of an aerosol coating is counted towards the product’s reactivity-based limit, as provided in 40 CFR part 59, subpart E. Therefore, the compounds that are used in aerosol coating products and that are identified in paragraphs (s)(1) or (s)(5) of this section as excluded from EPA’s definition of VOC are to be counted towards a product’s reactivity limit for the purposes of determining compliance with EPA’s aerosol coatings reactivity-based national regulation, as provided in 40 CFR part 59, subpart E.
(t)–(w) [Reserved]
(x) Time period means any period of time designated by hour, month, season, calendar year, averaging time, or other suitable characteristics, for which ambient air quality is estimated.
(y) Variance means the temporary deferral of a final compliance date for an individual source subject to an approved regulation, or a temporary change to an approved regulation as it applies to an individual source.
(z) Emission limitation and emission standard mean a requirement established by a State, local government, or the Administrator which limits the quantity, rate, or concentration of emissions of air pollutants on a continuous basis, including any requirements which limit the level of opacity, prescribe equipment, set fuel specifications, or prescribe operation or maintenance procedures for a source to assure continuous emission reduction.
(aa) Capacity factor means the ratio of the average load on a machine or equipment for the period of time considered to the capacity rating of the machine or equipment.
(bb) Excess emissions means emissions of an air pollutant in excess of an emission standard.
(cc) Nitric acid plant means any facility producing nitric acid 30 to 70 percent in strength by either the pressure or atmospheric pressure process.
(dd) Sulfuric acid plant means any facility producing sulfuric acid by the contact process by burning elemental sulfur, alkylation acid, hydrogen sulfide, or acid sludge, but does not include facilities where conversion to sulfuric acid is utilized primarily as a means of preventing emissions to the atmosphere of sulfur dioxide or other sulfur compounds.
(ee) Fossil fuel-fired steam generator means a furnance or bioler used in the process of burning fossil fuel for the primary purpose of producing steam by heat transfer.
(ff) Stack means any point in a source designed to emit solids, liquids, or gases into the air, including a pipe or duct but not including flares.
(gg) A stack in existence means that the owner or operator had (1) begun, or caused to begin, a continuous program of physical on-site construction of the stack or (2) entered into binding agreements or contractual obligations, which could not be cancelled or modified without substantial loss to the owner or operator, to undertake a program of construction of the stack to be completed within a reasonable time.
(hh)(1) Dispersion technique means any technique which attempts to affect the concentration of a pollutant in the ambient air by:
(i) Using that portion of a stack which exceeds good engineering practice stack height:
(ii) Varying the rate of emission of a pollutant according to atmospheric conditions or ambient concentrations of that pollutant; or
(iii) Increasing final exhaust gas plume rise by manipulating source process parameters, exhaust gas parameters, stack parameters, or combining exhaust gases from several existing stacks into one stack; or other selective handling of exhaust gas streams so as to increase the exhaust gas plume rise.
(2) The preceding sentence does not include:
(i) The reheating of a gas stream, following use of a pollution control system, for the purpose of returning the gas to the temperature at which it was originally discharged from the facility generating the gas stream;
(ii) The merging of exhaust gas streams where:
(A) The source owner or operator demonstrates that the facility was originally designed and constructed with such merged gas streams;
(B) After July 8, 1985 such merging is part of a change in operation at the facility that includes the installation of pollution controls and is accompanied by a net reduction in the allowable emissions of a pollutant. This exclusion from the definition of dispersion techniques shall apply only to the emission limitation for the pollutant affected by such change in operation; or
(C) Before July 8, 1985, such merging was part of a change in operation at the facility that included the installation of emissions control equipment or was carried out for sound economic or engineering reasons. Where there was an increase in the emission limitation or, in the event that no emission limitation was in existence prior to the merging, an increase in the quantity of pollutants actually emitted prior to the merging, the reviewing agency shall presume that merging was significantly motivated by an intent to gain emissions credit for greater dispersion. Absent a demonstration by the source owner or operator that merging was not significantly motivated by such intent, the reviewing agency shall deny credit for the effects of such merging in calculating the allowable emissions for the source;
(iii) Smoke management in agricultural or silvicultural prescribed burning programs;
(iv) Episodic restrictions on residential woodburning and open burning; or
(v) Techniques under § 51.100(hh)(1)(iii) which increase final exhaust gas plume rise where the resulting allowable emissions of sulfur dioxide from the facility do not exceed 5,000 tons per year.
(ii) Good engineering practice (GEP) stack height means the greater of:
(1) 65 meters, measured from the ground-level elevation at the base of the stack:
(2)(i) For stacks in existence on January 12, 1979, and for which the owner or operator had obtained all applicable permits or approvals required under 40 CFR parts 51 and 52.
(ii) For all other stacks,
(3) The height demonstrated by a fluid model or a field study approved by the EPA State or local control agency, which ensures that the emissions from a stack do not result in excessive concentrations of any air pollutant as a result of atmospheric downwash, wakes, or eddy effects created by the source itself, nearby structures or nearby terrain features.
(jj) Nearby as used in § 51.100(ii) of this part is defined for a specific structure or terrain feature and
(1) For purposes of applying the formulae provided in § 51.100(ii)(2) means that distance up to five times the lesser of the height or the width dimension of a structure, but not greater than 0.8 km (
(2) For conducting demonstrations under § 51.100(ii)(3) means not greater than 0.8 km (
(kk) Excessive concentration is defined for the purpose of determining good engineering practice stack height under § 51.100(ii)(3) and means:
(1) For sources seeking credit for stack height exceeding that established under § 51.100(ii)(2) a maximum ground-level concentration due to emissions from a stack due in whole or part to downwash, wakes, and eddy effects produced by nearby structures or nearby terrain features which individually is at least 40 percent in excess of the maximum concentration experienced in the absence of such downwash, wakes, or eddy effects and which contributes to a total concentration due to emissions from all sources that is greater than an ambient air quality standard. For sources subject to the prevention of significant deterioration program (40 CFR 51.166 and 52.21), an excessive concentration alternatively means a maximum ground-level concentration due to emissions from a stack due in whole or part to downwash, wakes, or eddy effects produced by nearby structures or nearby terrain features which individually is at least 40 percent in excess of the maximum concentration experienced in the absence of such downwash, wakes, or eddy effects and greater than a prevention of significant deterioration increment. The allowable emission rate to be used in making demonstrations under this part shall be prescribed by the new source performance standard that is applicable to the source category unless the owner or operator demonstrates that this emission rate is infeasible. Where such demonstrations are approved by the authority administering the State implementation plan, an alternative emission rate shall be established in consultation with the source owner or operator.
(2) For sources seeking credit after October 11, 1983, for increases in existing stack heights up to the heights established under § 51.100(ii)(2), either (i) a maximum ground-level concentration due in whole or part to downwash, wakes or eddy effects as provided in paragraph (kk)(1) of this section, except that the emission rate specified by any applicable State implementation plan (or, in the absence of such a limit, the actual emission rate) shall be used, or (ii) the actual presence of a local nuisance caused by the existing stack, as determined by the authority administering the State implementation plan; and
(3) For sources seeking credit after January 12, 1979 for a stack height determined under § 51.100(ii)(2) where the authority administering the State implementation plan requires the use of a field study or fluid model to verify GEP stack height, for sources seeking stack height credit after November 9, 1984 based on the aerodynamic influence of cooling towers, and for sources seeking stack height credit after December 31, 1970 based on the aerodynamic influence of structures not adequately represented by the equations in § 51.100(ii)(2), a maximum ground-level concentration due in whole or part to downwash, wakes or eddy effects that is at least 40 percent in excess of the maximum concentration experienced in the absence of such downwash, wakes, or eddy effects.
(ll)–(mm) [Reserved]
(nn) Intermittent control system (ICS) means a dispersion technique which varies the rate at which pollutants are emitted to the atmosphere according to meteorological conditions and/or ambient concentrations of the pollutant, in order to prevent ground-level concentrations in excess of applicable ambient air quality standards. Such a dispersion technique is an ICS whether used alone, used with other dispersion techniques, or used as a supplement to continuous emission controls (i.e., used as a supplemental control system).
(oo) Particulate matter means any airborne finely divided solid or liquid material with an aerodynamic diameter smaller than 100 micrometers.
(pp) Particulate matter emissions means all finely divided solid or liquid material, other than uncombined water, emitted to the ambient air as measured by applicable reference methods, or an equivalent or alternative method, specified in this chapter, or by a test method specified in an approved State implementation plan.
(qq) PM
(rr) PM
(ss) Total suspended particulate means particulate matter as measured by the method described in appendix B of part 50 of this chapter.
§ 51.101 Stipulations.
Nothing in this part will be construed in any manner:
(a) To encourage a State to prepare, adopt, or submit a plan which does not provide for the protection and enhancement of air quality so as to promote the public health and welfare and productive capacity.
(b) To encourage a State to adopt any particular control strategy without taking into consideration the cost-effectiveness of such control strategy in relation to that of alternative control strategies.
(c) To preclude a State from employing techniques other than those specified in this part for purposes of estimating air quality or demonstrating the adequacy of a control strategy, provided that such other techniques are shown to be adequate and appropriate for such purposes.
(d) To encourage a State to prepare, adopt, or submit a plan without taking into consideration the social and economic impact of the control strategy set forth in such plan, including, but not limited to, impact on availability of fuels, energy, transportation, and employment.
(e) To preclude a State from preparing, adopting, or submitting a plan which provides for attainment and maintenance of a national standard through the application of a control strategy not specifically identified or described in this part.
(f) To preclude a State or political subdivision thereof from adopting or enforcing any emission limitations or other measures or combinations thereof to attain and maintain air quality better than that required by a national standard.
(g) To encourage a State to adopt a control strategy uniformly applicable throughout a region unless there is no satisfactory alternative way of providing for attainment and maintenance of a national standard throughout such region.
§ 51.102 Public hearings.
(a) Except as otherwise provided in paragraph (c) of this section and within the 30 day notification period as required by paragraph (d) of this section, States must provide notice, provide the opportunity to submit written comments and allow the public the opportunity to request a public hearing. The State must hold a public hearing or provide the public the opportunity to request a public hearing. The notice announcing the 30 day notification period must include the date, place and time of the public hearing. If the State provides the public the opportunity to request a public hearing and a request is received the State must hold the scheduled hearing or schedule a public hearing (as required by paragraph (d) of this section). The State may cancel the public hearing through a method it identifies if no request for a public hearing is received during the 30 day notification period and the original notice announcing the 30 day notification period clearly states: If no request for a public hearing is received the hearing will be cancelled; identifies the method and time for announcing that the hearing has been cancelled; and provides a contact phone number for the public to call to find out if the hearing has been cancelled. These requirements apply for adoption and submission to EPA of:
(1) Any plan or revision of it required by § 51.104(a).
(2) Any individual compliance schedule under (§ 51.260).
(3) Any revision under § 51.104(d).
(b) Separate hearings may be held for plans to implement primary and secondary standards.
(c) No hearing will be required for any change to an increment of progress in an approved individual compliance schedule unless such change is likely to cause the source to be unable to comply with the final compliance date in the schedule. The requirements of §§ 51.104 and 51.105 will be applicable to such schedules, however.
(d) Any hearing required by paragraph (a) of this section will be held only after reasonable notice, which will be considered to include, at least 30 days prior to the date of such hearing(s):
(1) Notice given to the public by prominent advertisement in the area affected announcing the date(s), time(s), and place(s) of such hearing(s);
(2) Availability of each proposed plan or revision for public inspection in at least one location in each region to which it will apply, and the availability of each compliance schedule for public inspection in at least one location in the region in which the affected source is located;
(3) Notification to the Administrator (through the appropriate Regional Office);
(4) Notification to each local air pollution control agency which will be significantly impacted by such plan, schedule or revision;
(5) In the case of an interstate region, notification to any other States included, in whole or in part, in the regions which are significantly impacted by such plan or schedule or revision.
(e) The State must prepare and retain, for inspection by the Administrator upon request, a record of each hearing. The record must contain, as a minimum, a list of witnesses together with the text of each presentation.
(f) The State must submit with the plan, revision, or schedule, a certification that the requirements in paragraph (a) and (d) of this section were met. Such certification will include the date and place of any public hearing(s) held or that no public hearing was requested during the 30 day notification period.
(g) Upon written application by a State agency (through the appropriate Regional Office), the Administrator may approve State procedures for public hearings. The following criteria apply:
(1) Procedures approved under this section shall be deemed to satisfy the requirement of this part regarding public hearings.
(2) Procedures different from this part may be approved if they—
(i) Ensure public participation in matters for which hearings are required; and
(ii) Provide adequate public notification of the opportunity to participate.
(3) The Administrator may impose any conditions on approval he or she deems necessary.
§ 51.103 Submission of plans, preliminary review of plans.
(a) The State makes an official plan submission to EPA only when the submission conforms to the requirements of appendix V to this part and the State delivers the submission to EPA through one of the three following methods: An electronic submission through EPA’s eSIP submission system; one paper submission to the appropriate Regional Office with an exact duplicate electronic version, preferably in a word searchable format; or three paper submissions. Any State submission under this part, whether through the eSIP submission system or in paper copy form, will serve as the official submission.
(b) Upon request by a State, the Administrator will work with the State to provide preliminary review of a plan or portion thereof submitted in advance of the date such plan is due. Such requests must be made to the appropriate Regional Office, and must indicate changes (such as redline/strikethrough) to the existing approved plan where applicable, and be submitted using a format agreed upon by the State and Regional Office. Requests for preliminary review do not relieve a State of the responsibility of adopting and submitting plans in accordance with prescribed due dates.
(c) In addition to conforming to the requirements of appendix V to this part for complete SIP submissions, the EPA requests that the state consult with the appropriate Regional Office regarding any additional guidance for submitting a plan to EPA.
§ 51.104 Revisions.
(a) States may revise the plan from time to time consistent with the requirements applicable to implementation plans under this part.
(b) The States must submit any revision of any regulation or any compliance schedule under paragraph (c) of this section to the Administrator no later than 60 days after its adoption.
(c) EPA will approve revisions only after applicable hearing requirements of § 51.102 have been satisfied.
(d) In order for a variance to be considered for approval as a revision to the State implementation plan, the State must submit it in accordance with the requirements of this section.
§ 51.105 Approval of plans.
Revisions of a plan, or any portion thereof, will not be considered part of an applicable plan until such revisions have been approved by the Administrator in accordance with this part.
Subpart G—Control Strategy
§ 51.110 Attainment and maintenance of national standards.
(a) Each plan providing for the attainment of a primary or secondary standard must specify the projected attainment date.
(b)–(f) [Reserved]
(g) During developing of the plan, EPA encourages States to identify alternative control strategies, as well as the costs and benefits of each such alternative for attainment or maintenance of the national standard.
§ 51.111 Description of control measures.
Each plan must set forth a control strategy which includes the following:
(a) A description of enforcement methods including, but not limited to:
(1) Procedures for monitoring compliance with each of the selected control measures,
(2) Procedures for handling violations, and
(3) A designation of agency responsibility for enforcement of implementation.
(b) [Reserved]
§ 51.112 Demonstration of adequacy.
(a) Each plan must demonstrate that the measures, rules, and regulations contained in it are adequate to provide for the timely attainment and maintenance of the national standard that it implements.
(1) The adequacy of a control strategy shall be demonstrated by means of applicable air quality models, data bases, and other requirements specified in appendix W of this part (Guideline on Air Quality Models).
(2) Where an air quality model specified in appendix W of this part (Guideline on Air Quality Models) is inappropriate, the model may be modified or another model substituted. Such a modification or substitution of a model may be made on a case-by-case basis or, where appropriate, on a generic basis for a specific State program. Written approval of the Administrator must be obtained for any modification or substitution. In addition, use of a modified or substituted model must be subject to notice and opportunity for public comment under procedures set forth in § 51.102.
(b) The demonstration must include the following:
(1) A summary of the computations, assumptions, and judgments used to determine the degree of reduction of emissions (or reductions in the growth of emissions) that will result from the implementation of the control strategy.
(2) A presentation of emission levels expected to result from implementation of each measure of the control strategy.
(3) A presentation of the air quality levels expected to result from implementation of the overall control strategy presented either in tabular form or as an isopleth map showing expected maximum pollutant concentrations.
(4) A description of the dispersion models used to project air quality and to evaluate control strategies.
(5) For interstate regions, the analysis from each constituent State must, where practicable, be based upon the same regional emission inventory and air quality baseline.
§ 51.113 [Reserved]
§ 51.114 Emissions data and projections.
(a) Except for lead, each plan must contain a detailed inventory of emissions from point and area sources. Lead requirements are specified in § 51.117. The inventory must be based upon measured emissions or, where measured emissions are not available, documented emission factors.
(b) Each plan must contain a summary of emission levels projected to result from application of the new control strategy.
(c) Each plan must identify the sources of the data used in the projection of emissions.
§ 51.115 Air quality data and projections.
(a) Each plan must contain a summary of data showing existing air quality.
(b) Each plan must:
(1) Contain a summary of air quality concentrations expected to result from application of the control strategy, and
(2) Identify and describe the dispersion model, other air quality model, or receptor model used.
(c) Actual measurements of air quality must be used where available if made by methods specified in appendix C to part 58 of this chapter. Estimated air quality using appropriate modeling techniques may be used to supplement measurements.
(d) For purposes of developing a control strategy, background concentration shall be taken into consideration with respect to particulate matter. As used in this subpart, background concentration is that portion of the measured ambient levels that cannot be reduced by controlling emissions from man-made sources.
(e) In developing an ozone control strategy for a particular area, background ozone concentrations and ozone transported into an area must be considered. States may assume that the ozone standard will be attained in upwind areas.
§ 51.116 Data availability.
(a) The State must retain all detailed data and calculations used in the preparation of each plan or each plan revision, and make them available for public inspection and submit them to the Administrator at his request.
(b) The detailed data and calculations used in the preparation of plan revisions are not considered a part of the plan.
(c) Each plan must provide for public availability of emission data reported by source owners or operators or otherwise obtained by a State or local agency. Such emission data must be correlated with applicable emission limitations or other measures. As used in this paragraph, correlated means presented in such a manner as to show the relationship between measured or estimated amounts of emissions and the amounts of such emissions allowable under the applicable emission limitations or other measures.
§ 51.117 Additional provisions for lead.
In addition to other requirements in §§ 51.100 through 51.116 the following requirements apply to lead. To the extent they conflict, there requirements are controlling over those of the proceeding sections.
(a) Control strategy demonstration. Each plan must contain a demonstration showing that the plan will attain and maintain the standard in the following areas:
(1) Areas in the vicinity of the following point sources of lead: Primary lead smelters, Secondary lead smelters, Primary copper smelters, Lead gasoline additive plants, Lead-acid storage battery manufacturing plants that produce 2,000 or more batteries per day. Any other stationary source that actually emits 25 or more tons per year of lead or lead compounds measured as elemental lead.
(2) Any other area that has lead air concentrations in excess of the national ambient air quality standard concentration for lead, measured since January 1, 1974.
(b) Time period for demonstration of adequacy. The demonstration of adequacy of the control strategy required under § 51.112 may cover a longer period if allowed by the appropriate EPA Regional Administrator.
(c) Special modeling provisions. (1) For urbanized areas with measured lead concentrations in excess of 4.0 µg/m
(2) For each point source listed in § 51.117(a), that plan must employ an atmospheric dispersion model for demonstration of attainment, consistent with requirements contained in § 51.112(a).
(3) For each area in the vicinity of an air quality monitor that has recorded lead concentrations in excess of the lead national standard concentration, the plan must employ the modified rollback model as a minimum, but may use an atmospheric dispersion model if desired for the demonstration of attainment, consistent with requirements contained in § 51.112(a).
(d) Air quality data and projections. (1) Each State must submit to the appropriate EPA Regional Office with the plan, but not part of the plan, all lead air quality data measured since January 1, 1974. This requirement does not apply if the data has already been submitted.
(2) The data must be submitted in accordance with the procedures and data forms specified in Chapter 3.4.0 of the “AEROS User’s Manual” concerning storage and retrieval of aerometric data (SAROAD) except where the Regional Administrator waives this requirement.
(3) If additional lead air quality data are desired to determine lead air concentrations in areas suspected of exceeding the lead national ambient air quality standard, the plan may include data from any previously collected filters from particulate matter high volume samplers. In determining the lead content of the filters for control strategy demonstration purposes, a State may use, in addition to the reference method, X-ray fluorescence or any other method approved by the Regional Administrator.
(e) Emissions data. (1) The point source inventory on which the summary of the baseline for lead emissions inventory is based must contain all sources that emit 0.5 or more tons of lead per year.
(2) Each State must submit lead emissions data to the appropriate EPA Regional Office with the original plan. The submission must be made with the plan, but not as part of the plan, and must include emissions data and information related to point and area source emissions. The emission data and information should include the information identified in the Hazardous and Trace Emissions System (HATREMS) point source coding forms for all point sources and the area source coding forms for all sources that are not point sources, but need not necessarily be in the format of those forms.
§ 51.118 Stack height provisions.
(a) The plan must provide that the degree of emission limitation required of any source for control of any air pollutant must not be affected by so much of any source’s stack height that exceeds good engineering practice or by any other dispersion technique, except as provided in § 51.118(b). The plan must provide that before a State submits to EPA a new or revised emission limitation that is based on a good engineering practice stack height that exceeds the height allowed by § 51.100(ii) (1) or (2), the State must notify the public of the availabilty of the demonstration study and must provide opportunity for a public hearing on it. This section does not require the plan to restrict, in any manner, the actual stack height of any source.
(b) The provisions of § 51.118(a) shall not apply to (1) stack heights in existence, or dispersion techniques implemented on or before December 31, 1970, except where pollutants are being emitted from such stacks or using such dispersion techniques by sources, as defined in section 111(a)(3) of the Clean Air Act, which were constructed, or reconstructed, or for which major modifications, as defined in §§ 51.165(a)(1)(v)(A), 51.166(b)(2)(i) and 52.21(b)(2)(i), were carried out after December 31, 1970; or (2) coal-fired steam electric generating units subject to the provisions of section 118 of the Clean Air Act, which commenced operation before July 1, 1957, and whose stacks were construced under a construction contract awarded before February 8, 1974.
§ 51.119 Intermittent control systems.
(a) The use of an intermittent control system (ICS) may be taken into account in establishing an emission limitation for a pollutant under a State implementation plan, provided:
(1) The ICS was implemented before December 31, 1970, according to the criteria specified in § 51.119(b).
(2) The extent to which the ICS is taken into account is limited to reflect emission levels and associated ambient pollutant concentrations that would result if the ICS was the same as it was before December 31, 1970, and was operated as specified by the operating system of the ICS before December 31, 1970.
(3) The plan allows the ICS to compensate only for emissions from a source for which the ICS was implemented before December 31, 1970, and, in the event the source has been modified, only to the extent the emissions correspond to the maximum capacity of the source before December 31, 1970. For purposes of this paragraph, a source for which the ICS was implemented is any particular structure or equipment the emissions from which were subject to the ICS operating procedures.
(4) The plan requires the continued operation of any constant pollution control system which was in use before December 31, 1970, or the equivalent of that system.
(5) The plan clearly defines the emission limits affected by the ICS and the manner in which the ICS is taken into account in establishing those limits.
(6) The plan contains requirements for the operation and maintenance of the qualifying ICS which, together with the emission limitations and any other necessary requirements, will assure that the national ambient air quality standards and any applicable prevention of significant deterioration increments will be attained and maintained. These requirements shall include, but not necessarily be limited to, the following:
(i) Requirements that a source owner or operator continuously operate and maintain the components of the ICS specified at § 51.119(b)(3) (ii)–(iv) in a manner which assures that the ICS is at least as effective as it was before December 31, 1970. The air quality monitors and meteorological instrumentation specified at § 51.119(b) may be operated by a local authority or other entity provided the source has ready access to the data from the monitors and instrumentation.
(ii) Requirements which specify the circumstances under which, the extent to which, and the procedures through which, emissions shall be curtailed through the activation of ICS.
(iii) Requirements for recordkeeping which require the owner or operator of the source to keep, for periods of at least 3 years, records of measured ambient air quality data, meteorological information acquired, and production data relating to those processes affected by the ICS.
(iv) Requirements for reporting which require the owner or operator of the source to notify the State and EPA within 30 days of a NAAQS violation pertaining to the pollutant affected by the ICS.
(7) Nothing in this paragraph affects the applicability of any new source review requirements or new source performance standards contained in the Clean Air Act or 40 CFR subchapter C. Nothing in this paragraph precludes a State from taking an ICS into account in establishing emission limitations to any extent less than permitted by this paragraph.
(b) An intermittent control system (ICS) may be considered implemented for a pollutant before December 31, 1970, if the following criteria are met:
(1) The ICS must have been established and operational with respect to that pollutant prior to December 31, 1970, and reductions in emissions of that pollutant must have occurred when warranted by meteorological and ambient monitoring data.
(2) The ICS must have been designed and operated to meet an air quality objective for that pollutant such as an air quality level or standard.
(3) The ICS must, at a minimum, have included the following components prior to December 31, 1970:
(i) Air quality monitors. An array of sampling stations whose location and type were consistent with the air quality objective and operation of the system.
(ii) Meteorological instrumentation. A meteorological data acquisition network (may be limited to a single station) which provided meteorological prediction capabilities sufficient to determine the need for, and degree of, emission curtailments necessary to achieve the air quality design objective.
(iii) Operating system. A system of established procedures for determining the need for curtailments and for accomplishing such curtailments. Documentation of this system, as required by paragraph (n)(4), may consist of a compendium of memoranda or comparable material which define the criteria and procedures for curtailments and which identify the type and number of personnel authorized to initiate curtailments.
(iv) Meteorologist. A person, schooled in meteorology, capable of interpreting data obtained from the meteorological network and qualified to forecast meteorological incidents and their effect on ambient air quality. Sources may have obtained meteorological services through a consultant. Services of such a consultant could include sufficient training of source personnel for certain operational procedures, but not for design, of the ICS.
(4) Documentation sufficient to support the claim that the ICS met the criteria listed in this paragraph must be provided. Such documentation may include affidavits or other documentation.
§ 51.120 Requirements for State Implementation Plan revisions relating to new motor vehicles.
(a) The EPA Administrator finds that the State Implementation Plans (SIPs) for the States of Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont, the portion of Virginia included (as of November 15, 1990) within the Consolidated Metropolitan Statistical Area that includes the District of Columbia, are substantially inadequate to comply with the requirements of section 110(a)(2)(D) of the Clean Air Act, 42 U.S.C. 7410(a)(2)(D), and to mitigate adequately the interstate pollutant transport described in section 184 of the Clean Air Act, 42 U.S.C. 7511C, to the extent that they do not provide for emission reductions from new motor vehicles in the amount that would be achieved by the Ozone Transport Commission low emission vehicle (OTC LEV) program described in paragraph (c) of this section. This inadequacy will be deemed cured for each of the aforementioned States (including the District of Columbia) in the event that EPA determines through rulemaking that a national LEV-equivalent new motor vehicle emission control program is an acceptable alternative for OTC LEV and finds that such program is in effect. In the event no such finding is made, each of those States must adopt and submit to EPA by February 15, 1996 a SIP revision meeting the requirements of paragraph (b) of this section in order to cure the SIP inadequacy.
(b) If a SIP revision is required under paragraph (a) of this section, it must contain the OTC LEV program described in paragraph (c) of this section unless the State adopts and submits to EPA, as a SIP revision, other emission-reduction measures sufficient to meet the requirements of paragraph (d) of this section. If a State adopts and submits to EPA, as a SIP revision, other emission-reduction measures pursuant to paragraph (d) of this section, then for purposes of determining whether such a SIP revision is complete within the meaning of section 110(k)(1) (and hence is eligible at least for consideration to be approved as satisfying paragraph (d) of this section), such a SIP revision must contain other adopted emission-reduction measures that, together with the identified potentially broadly practicable measures, achieve at least the minimum level of emission reductions that could potentially satisfy the requirements of paragraph (d) of this section. All such measures must be fully adopted and enforceable.
(c) The OTC LEV program is a program adopted pursuant to section 177 of the Clean Air Act.
(1) The OTC LEV program shall contain the following elements:
(i) It shall apply to all new 1999 and later model year passenger cars and light-duty trucks (0–5750 pounds loaded vehicle weight), as defined in Title 13, California Code of Regulations, section 1900(b)(11) and (b)(8), respectively, that are sold, imported, delivered, purchased, leased, rented, acquired, received, or registered in any area of the State that is in the Northeast Ozone Transport Region as of December 19, 1994.
(ii) All vehicles to which the OTC LEV program is applicable shall be required to have a certificate from the California Air Resources Board (CARB) affirming compliance with California standards.
(iii) All vehicles to which this LEV program is applicable shall be required to meet the mass emission standards for Non-Methane Organic Gases (NMOG), Carbon Monoxide (CO), Oxides of Nitrogen (NO
(iv) All manufacturers of vehicles subject to the OTC LEV program shall be required to meet the fleet average NMOG exhaust emission values for production and delivery for sale of their passenger cars, light-duty trucks 0–3750 pounds loaded vehicle weight, and light-duty trucks 3751–5750 pounds loaded vehicle weight specified in Title 13, California Code of Regulations, section 1960.1(g)(2) for each model year beginning in 1999. A State may determine not to implement the NMOG fleet average in the first model year of the program if the State begins implementation of the program late in a calendar year. However, all States must implement the NMOG fleet average in any full model years of the LEV program.
(v) All manufacturers shall be allowed to average, bank and trade credits in the same manner as allowed under the program specified in Title 13, California Code of Regulations, section 1960.1(g)(2) footnote 7 for each model year beginning in 1999. States may account for credits banked by manufacturers in California or New York in years immediately preceding model year 1999, in a manner consistent with California banking and discounting procedures.
(vi) The provisions for small volume manufacturers and intermediate volume manufacturers, as applied by Title 13, California Code of Regulations to California’s LEV program, shall apply. Those manufacturers defined as small volume manufacturers and intermediate volume manufacturers in California under California’s regulations shall be considered small volume manufacturers and intermediate volume manufacturers under this program.
(vii) The provisions for hybrid electric vehicles (HEVs), as defined in Title 13 California Code of Regulations, section 1960.1, shall apply for purposes of calculating fleet average NMOG values.
(viii) The provisions for fuel-flexible vehicles and dual-fuel vehicles specified in Title 13, California Code of Regulations, section 1960.1(g)(1) footnote 4 shall apply.
(ix) The provisions for reactivity adjustment factors, as defined by Title 13, California Code of Regulations, shall apply.
(x) The aforementioned State OTC LEV standards shall be identical to the aforementioned California standards as such standards exist on December 19, 1994.
(xi) All States’ OTC LEV programs must contain any other provisions of California’s LEV program specified in Title 13, California Code of Regulations necessary to comply with section 177 of the Clean Air Act.
(2) States are not required to include the mandate for production of ZEVs specified in Title 13, California Code of Regulations, section 1960.1(g)(2) footnote 9.
(3) Except as specified elsewhere in this section, States may implement the OTC LEV program in any manner consistent with the Act that does not decrease the emissions reductions or jeopardize the effectiveness of the program.
(d) The SIP revision that paragraph (b) of this section describes as an alternative to the OTC LEV program described in paragraph (c) of this section must contain a set of State-adopted measures that provides at least the following amount of emission reductions in time to bring serious ozone nonattainment areas into attainment by their 1999 attainment date:
(1) Reductions at least equal to the difference between:
(i) The nitrogen oxides (NO
(ii) A reduction in NO
(2) Reductions at least equal to the difference between:
(i) The VOC emission reductions from the 1990 statewide emissions inventory achievable through implementation of all of the Clean Air Act-mandated and potentially broadly practicable control measures in all portions of the State in, or near and upwind of, any of the serious or severe ozone nonattainment areas lying in the series of such areas running northeast from the Washington, DC, ozone nonattainment area to and including the Portsmouth, New Hampshire ozone nonattainment area; and
(ii) A reduction in VOC emissions from the 1990 emissions inventory in all such areas of 50% or whatever greater reduction is necessary to prevent significant contribution to nonattainment in, or interference with maintenance by, any downwind State.
§ 51.121 Findings and requirements for submission of State implementation plan revisions relating to emissions of nitrogen oxides.
(a)(1) The Administrator finds that the State implementation plan (SIP) for each jurisdiction listed in paragraph (c) of this section is substantially inadequate to comply with the requirements of section 110(a)(2)(D)(i)(I) of the Clean Air Act (CAA), 42 U.S.C. 7410(a)(2)(D)(i)(I), because the SIP does not include adequate provisions to prohibit sources and other activities from emitting nitrogen oxides (“NO
(2) [Reserved]
(3) As used in this section, these terms shall have the following meanings:
Nitrogen oxides or NO
Ozone season means the period from May 1 to September 30 of a year.
Phase I SIP submission means a SIP revision submitted by a State on or before October 30, 2000 in compliance with paragraph (b)(1)(ii) of this section to limit projected NO
Phase II SIP submission means a SIP revision submitted by a State in compliance with paragraph (b)(1)(ii) of this section to limit projected NO
(b)(1) For each jurisdiction listed in paragraph (c) of this section, each SIP revision required under paragraph (a) of this section will contain adequate provisions, for purposes of complying with section 110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 7410(a)(2)(D)(i)(I), only if the SIP revision:
(i) Contains control measures adequate to prohibit emissions of NO
(ii) Requires full implementation of all such control measures by no later than May 31, 2004 for the sources covered by a Phase I SIP submission and May 1, 2007 for the sources covered by a Phase II SIP submission; and
(iii) Meets the other requirements of this section. The SIP revision’s compliance with the requirement of paragraph (b)(1)(i) of this section shall be considered compliance with the jurisdiction’s NO
(2) [Reserved]
(c) The following jurisdictions (hereinafter referred to as “States”) are subject to the requirement of this section:
(1) Connecticut, Delaware, Illinois, Indiana, Kentucky, Maryland, Massachusetts, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, West Virginia, and the District of Columbia.
(2) The portions of Alabama, Michigan, and Missouri within the fine grid of the OTAG modeling domain. The fine grid is the area encompassed by a box with the following geographic coordinates: Southwest Corner, 92 degrees West longitude and 32 degrees North latitude; and Northeast Corner, 69.5 degrees West longitude and 44 degrees North latitude.
(d)(1) [Reserved]
(2) Each SIP submission under this section must comply with § 51.103 (regarding submission of plans).
(e)(1) Except as provided in paragraph (e)(2)(ii) of this section, the NO
(2)(i) The State-by-State amounts of the Phase I and final NO
Table 1 to Paragraph (
State | Phase I NO (2004–2006) | Final NO (2007 and thereafter) |
---|---|---|
Alabama | 124,795 | 119,827 |
Connecticut | 42,891 | 42,850 |
Delaware | 23,522 | 22,862 |
District of Columbia | 6,658 | 6,657 |
Illinois | 278,146 | 271,091 |
Indiana | 234,625 | 230,381 |
Kentucky | 165,075 | 162,519 |
Maryland | 82,727 | 81,947 |
Massachusetts | 85,871 | 84,848 |
Michigan | 191,941 | 190,908 |
Missouri | 61,406 | |
New Jersey | 95,882 | 96,876 |
New York | 241,981 | 240,322 |
North Carolina | 171,332 | 165,306 |
Ohio | 252,282 | 249,541 |
Pennsylvania | 268,158 | 257,928 |
Rhode Island | 9,570 | 9,378 |
South Carolina | 127,756 | 123,496 |
Tennessee | 201,163 | 198,286 |
Virginia | 186,689 | 180,521 |
West Virginia | 85,045 | 83,921 |
(ii) (A) For purposes of paragraph (e)(2)(i) of this section, in the case of each State listed in paragraphs (e)(2)(ii)(B) through (E) of this section, the NO
(B) In the case of Alabama, the counties are: Autauga, Bibb, Blount, Calhoun, Chambers, Cherokee, Chilton, Clay, Cleburne, Colbert, Coosa, Cullman, Dallas, DeKalb, Elmore, Etowah, Fayette, Franklin, Greene, Hale, Jackson, Jefferson, Lamar, Lauderdale, Lawrence, Lee, Limestone, Macon, Madison, Marion, Marshall, Morgan, Perry, Pickens, Randolph, Russell, St. Clair, Shelby, Sumter, Talladega, Tallapoosa, Tuscaloosa, Walker, and Winston.
(C) [Reserved]
(D) In the case of Michigan, the counties are: Allegan, Barry, Bay, Berrien, Branch, Calhoun, Cass, Clinton, Eaton, Genesee, Gratiot, Hillsdale, Ingham, Ionia, Isabella, Jackson, Kalamazoo, Kent, Lapeer, Lenawee, Livingston, Macomb, Mecosta, Midland, Monroe, Montcalm, Muskegon, Newaygo, Oakland, Oceana, Ottawa, Saginaw, St. Clair, St. Joseph, Sanilac, Shiawassee, Tuscola, Van Buren, Washtenaw, and Wayne.
(E) In the case of Missouri, the counties are: Bollinger, Butler, Cape Girardeau, Carter, Clark, Crawford, Dent, Dunklin, Franklin, Gasconade, Iron, Jefferson, Lewis, Lincoln, Madison, Marion, Mississippi, Montgomery, New Madrid, Oregon, Pemiscot, Perry, Pike, Ralls, Reynolds, Ripley, St. Charles, St. Francois, St. Louis, St. Louis City, Ste. Genevieve, Scott, Shannon, Stoddard, Warren, Washington, and Wayne.
(f) Each SIP revision must set forth control measures to meet the NO
(1) A description of enforcement methods including, but not limited to:
(i) Procedures for monitoring compliance with each of the selected control measures;
(ii) Procedures for handling violations; and
(iii) A designation of agency responsibility for enforcement of implementation.
(2) Should a State elect to impose control measures on fossil fuel-fired NO
(i)(A) Impose a NO
(B) Impose a NO
(C) Impose any other regulatory requirement which the State has demonstrated to EPA provides equivalent or greater assurance than options in paragraph (f)(2)(i)(A) or (B) of this section that the State will comply with its NO
(ii) Impose enforceable mechanisms, in accordance with paragraphs (b)(1)(i) and (ii) of this section, to assure that collectively all such sources, including new or modified units, will not exceed in the 2007 ozone season the total NO
(3) For purposes of paragraph (f)(2) of this section, the term “fossil fuel-fired” means, with regard to a NO
(i) The combustion of fossil fuel, alone or in combination with any other fuel, where fossil fuel actually combusted comprises more than 50 percent of the annual heat input on a Btu basis during any year starting in 1995 or, if a NO
(ii) The combustion of fossil fuel, alone or in combination with any other fuel, where fossil fuel is projected to comprise more than 50 percent of the annual heat input on a Btu basis during any year; provided that the NO
(g)(1) Each SIP revision must demonstrate that the control measures contained in it are adequate to provide for the timely compliance with the State’s NO
(2) The demonstration must include the following:
(i) Each revision must contain a detailed baseline inventory of NO
(ii) [Reserved]
(iii) Each revision must contain a summary of NO
(iv) Each revision must identify the sources of the data used in the projection of emissions.
(h) Each revision must comply with § 51.116 (regarding data availability).
(i) Each revision must provide for monitoring the status of compliance with any control measures adopted to meet the NO
(1) The revision must provide for legally enforceable procedures for requiring owners or operators of stationary sources to maintain records of and periodically report to the State:
(i) Information on the amount of NO
(ii) Other information as may be necessary to enable the State to determine whether the sources are in compliance with applicable portions of the control measures;
(2) The revision must comply with § 51.212 (regarding testing, inspection, enforcement, and complaints);
(3) If the revision contains any transportation control measures, then the revision must comply with § 51.213 (regarding transportation control measures);
(4) If the revision contains measures to control fossil fuel-fired NO
(5) For purposes of paragraph (i)(4) of this section, the term “fossil fuel-fired” has the meaning set forth in paragraph (f)(3) of this section.
(j) Each revision must show that the State has legal authority to carry out the revision, including authority to:
(1) Adopt emissions standards and limitations and any other measures necessary for attainment and maintenance of the State’s NO
(2) Enforce applicable laws, regulations, and standards, and seek injunctive relief;
(3) Obtain information necessary to determine whether air pollution sources are in compliance with applicable laws, regulations, and standards, including authority to require recordkeeping and to make inspections and conduct tests of air pollution sources;
(4) Require owners or operators of stationary sources to install, maintain, and use emissions monitoring devices and to make periodic reports to the State on the nature and amounts of emissions from such stationary sources; also authority for the State to make such data available to the public as reported and as correlated with any applicable emissions standards or limitations.
(k)(1) The provisions of law or regulation which the State determines provide the authorities required under this section must be specifically identified, and copies of such laws or regulations must be submitted with the SIP revision.
(2) Legal authority adequate to fulfill the requirements of paragraphs (j)(3) and (4) of this section may be delegated to the State under section 114 of the CAA, 42 U.S.C. 7414.
(l)(1) A revision may assign legal authority to local agencies in accordance with § 51.232.
(2) Each revision must comply with § 51.240 (regarding general plan requirements).
(m) Each revision must comply with § 51.280 (regarding resources).
(n) For purposes of the SIP revisions required by this section, EPA may make a finding as applicable under section 179(a)(1)–(4) of the CAA, 42 U.S.C. 7509(a)(1)–(4), starting the sanctions process set forth in section 179(a) of the CAA. Any such finding will be deemed a finding under 40 CFR 52.31(c) and sanctions will be imposed in accordance with the order of sanctions and the terms for such sanctions established in 40 CFR 52.31.
(o) Each revision must provide for State compliance with the reporting requirements set forth in § 51.122.
(p)–(q) [Reserved]
(r)(1) Notwithstanding any provisions of subparts A through I of 40 CFR part 96 and any State’s SIP to the contrary, with regard to any ozone season that occurs after September 30, 2008, the Administrator will not carry out any of the functions set forth for the Administrator in subparts A through I of 40 CFR part 96 or in any emissions trading program provisions in a State’s SIP approved under this section.
(2) Except as provided in 40 CFR 52.38(b)(13)(ii), a State whose SIP is approved as meeting the requirements of this section and that includes or included an emissions trading program approved under this section must revise the SIP to adopt control measures that satisfy the same portion of the State’s NO
§ 51.122 Emissions reporting requirements for SIP revisions relating to budgets for NOX emissions.
(a) As used in this section, words and terms shall have the meanings set forth in § 51.50. In addition, the following terms shall apply to this section:
(1) Ozone season emissions means emissions during the period from May 1 through September 30 of a year.
(2) Summer day emissions means an average day’s emissions for a typical summer work weekday. The state will select the particular month(s) in summer and the day(s) in the work week to be represented.
(b) For its transport SIP revision under § 51.121, each state must submit to EPA NO
(c) Each revision must provide for periodic reporting by the state of NO
(1) For the every-year reporting cycle, each revision must provide for reporting of NO
(i) The state must report to EPA emissions data from all NO
(ii) If sources report NO
(2) For the 3-year cycle reporting, each plan must provide for triennial (i.e., every third year) reporting of NO
(3) The data availability requirements in § 51.116 must be followed for all data submitted to meet the requirements of paragraphs (c)(1) and (2) of this section.
(d) [Reserved]
(e) Each state must submit for EPA approval an example of the calculation procedure used to calculate ozone season emissions along with sufficient information to verify the calculated value of ozone season emissions.
(f) Data collection is to begin during the ozone season 1 year prior to the state’s NO
(g) The state shall report emissions as point sources according to the point source emissions thresholds of the Air Emissions Reporting Rule (AERR), 40 CFR part 51, subpart A. The detail of the emissions inventory shall be consistent with the data elements required by 40 CFR part 51, subpart A. When submitting a formal NO
§ 51.123 Findings and requirements for submission of State implementation plan revisions relating to emissions of oxides of nitrogen pursuant to the Clean Air Interstate Rule.
(a)(1) Under section 110(a)(1) of the CAA, 42 U.S.C. 7410(a)(1), the Administrator determines that each State identified in paragraph (c)(1) and (2) of this section must submit a SIP revision to comply with the requirements of section 110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 7410(a)(2)(D)(i)(I), through the adoption of adequate provisions prohibiting sources and other activities from emitting NO
(2)(a) Under section 110(a)(1) of the CAA, 42 U.S.C. 7410(a)(1), the Administrator determines that each State identified in paragraph (c)(1) and (3) of this section must submit a SIP revision to comply with the requirements of section 110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 7410(a)(2)(D)(i)(I), through the adoption of adequate provisions prohibiting sources and other activities from emitting NO
(3) Notwithstanding the other provisions of this section, such provisions are not applicable as they relate to the State of Minnesota as of December 3, 2009.
(b) For each State identified in paragraph (c) of this section, the SIP revision required under paragraph (a) of this section will contain adequate provisions, for purposes of complying with section 110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 7410(a)(2)(D)(i)(I), only if the SIP revision contains control measures that assure compliance with the applicable requirements of this section.
(c) In addition to being subject to the requirements in paragraphs (b) and (d) of this section:
(1) Alabama, Delaware, Florida, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maryland, Michigan, Mississippi, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Virginia, West Virginia, Wisconsin, and the District of Columbia shall be subject to the requirements contained in paragraphs (e) through (cc) of this section;
(2) Georgia, Minnesota, and Texas shall be subject to the requirements in paragraphs (e) through (o) and (cc) of this section; and
(3) Arkansas, Connecticut, and Massachusetts shall be subject to the requirements contained in paragraphs (q) through (cc) of this section.
(d)(1) The State’s SIP revision under paragraph (a) of this section must be submitted to EPA by no later than September 11, 2006.
(2) The requirements of appendix V to this part shall apply to the SIP revision under paragraph (a) of this section.
(3) The State shall deliver 5 copies of the SIP revision under paragraph (a) of this section to the appropriate Regional Office, with a letter giving notice of such action.
(e) The State’s SIP revision shall contain control measures and demonstrate that they will result in compliance with the State’s Annual EGU NO
(1)(i) The Annual EGU NO
(ii) The Annual Non-EGU NO
(iii) If a State meets the requirements of paragraph (a)(1) of this section by imposing control measures on both EGUs and non-EGUs, then:
(A) The Annual Non-EGU NO
(B) The Annual EGU NO
(2) For a State that complies with the requirements of paragraph (a)(1) of this section by imposing control measures on only EGUs, the amount of the Annual EGU NO
State | Annual EGU NO | Annual EGU NO |
---|---|---|
Alabama | 69,020 | 57,517 |
Delaware | 4,166 | 3,472 |
District of Columbia | 144 | 120 |
Florida | 99,445 | 82,871 |
Georgia | 66,321 | 55,268 |
Illinois | 76,230 | 63,525 |
Indiana | 108,935 | 90,779 |
Iowa | 32,692 | 27,243 |
Kentucky | 83,205 | 69,337 |
Louisiana | 35,512 | 29,593 |
Maryland | 27,724 | 23,104 |
Michigan | 65,304 | 54,420 |
Minnesota | 31,443 | 26,203 |
Mississippi | 17,807 | 14,839 |
Missouri | 59,871 | 49,892 |
New Jersey | 12,670 | 10,558 |
New York | 45,617 | 38,014 |
North Carolina | 62,183 | 51,819 |
Ohio | 108,667 | 90,556 |
Pennsylvania | 99,049 | 82,541 |
South Carolina | 32,662 | 27,219 |
Tennessee | 50,973 | 42,478 |
Texas | 181,014 | 150,845 |
Virginia | 36,074 | 30,062 |
West Virginia | 74,220 | 61,850 |
Wisconsin | 40,759 | 33,966 |
(3) For a State that complies with the requirements of paragraph (a)(1) of this section by imposing control measures on only non-EGUs, the amount of the Annual Non-EGU NO
(4)(i) Notwithstanding the State’s obligation to comply with paragraph (e)(2) or (3) of this section, the State’s SIP revision may allow sources required by the revision to implement control measures to demonstrate compliance using credit issued from the State’s compliance supplement pool, as set forth in paragraph (e)(4)(ii) of this section.
(ii) The State-by-State amounts of the compliance supplement pool are as follows:
State | Compliance supplement pool |
---|---|
Alabama | 10,166 |
Delaware | 843 |
District of Columbia | 0 |
Florida | 8,335 |
Georgia | 12,397 |
Illinois | 11,299 |
Indiana | 20,155 |
Iowa | 6,978 |
Kentucky | 14,935 |
Louisiana | 2,251 |
Maryland | 4,670 |
Michigan | 8,347 |
Minnesota | 6,528 |
Mississippi | 3,066 |
Missouri | 9,044 |
New Jersey | 660 |
New York | 0 |
North Carolina | 0 |
Ohio | 25,037 |
Pennsylvania | 16,009 |
South Carolina | 2,600 |
Tennessee | 8,944 |
Texas | 772 |
Virginia | 5,134 |
West Virginia | 16,929 |
Wisconsin | 4,898 |
(iii) The SIP revision may provide for the distribution of credits from the compliance supplement pool to sources that are required to implement control measures using one or both of the following two mechanisms:
(A) The State may issue credit from compliance supplement pool to sources that are required by the SIP revision to implement NO
(1) The State shall complete the issuance process by January 1, 2010.
(2) The emissions reductions for which credits are issued must have been demonstrated by the owners and operators of the source to have occurred during 2007 and 2008 and not to be necessary to comply with any applicable State or federal emissions limitation.
(3) The emissions reductions for which credits are issued must have been quantified by the owners and operators of the source:
(i) For EGUs and for fossil-fuel-fired non-EGUs that are boilers or combustion turbines with a maximum design heat input greater than 250 mmBut/hr, using emissions data determined in accordance with subpart H of part 75 of this chapter; and
(ii) For non-EGUs not described in paragraph (e)(4)(iii)(A)(3)(i) of this section, using emissions data determined in accordance with subpart H of part 75 of this chapter or, if the State demonstrates that compliance with subpart H of part 75 of this chapter is not practicable, determined, to the extent practicable, with the same degree of assurance with which emissions data are determined for sources subject to subpart H of part 75.
(4) If the SIP revision contains approved provisions for an emissions trading program, the owners and operators of sources that receive credit according to the requirements of this paragraph may transfer the credit to other sources or persons according to the provisions in the emissions trading program.
(B) The State may issue credit from the compliance supplement pool to sources that are required by the SIP revision to implement NO
(1) The State shall complete the issuance process by January 1, 2010.
(2) The State shall issue credit to a source only if the owners and operators of the source demonstrate that:
(i) For a source used to generate electricity, implementation of the SIP revision’s applicable control measures by 2009 would create undue risk for the reliability of the electricity supply. This demonstration must include a showing that it would not be feasible for the owners and operators of the source to obtain a sufficient amount of electricity, to prevent such undue risk, from other electricity generation facilities during the installation of control technology at the source necessary to comply with the SIP revision.
(ii) For a source not used to generate electricity, compliance with the SIP revision’s applicable control measures by 2009 would create undue risk for the source or its associated industry to a degree that is comparable to the risk described in paragraph (e)(4)(iii)(B)(2)(i) of this section.
(iii) This demonstration must include a showing that it would not be possible for the source to comply with applicable control measures by obtaining sufficient credits under paragraph (e)(4)(iii)(A) of this section, or by acquiring sufficient credits from other sources or persons, to prevent undue risk.
(f) Each SIP revision must set forth control measures to meet the amounts specified in paragraph (e) of this section, as applicable, including the following:
(1) A description of enforcement methods including, but not limited to:
(i) Procedures for monitoring compliance with each of the selected control measures;
(ii) Procedures for handling violations; and
(iii) A designation of agency responsibility for enforcement of implementation.
(2)(i) If a State elects to impose control measures on EGUs, then those measures must impose an annual NO
(ii) If a State elects to impose control measures on fossil fuel-fired non-EGUs that are boilers or combustion turbines with a maximum design heat input greater than 250 mmBtu/hr, then those measures must impose an annual NO
(iii) If a State elects to impose control measures on non-EGUs other than those described in paragraph (f)(2)(ii) of this section, then those measures must impose an annual NO
(g)(1) Each SIP revision that contains control measures covering non-EGUs as part or all of a State’s obligation in meeting its requirement under paragraph (a)(1) of this section must demonstrate that such control measures are adequate to provide for the timely compliance with the State’s Annual Non-EGU NO
(2) The demonstration under paragraph (g)(1) of this section must include the following, with respect to each source category of non-EGUs for which the SIP revision requires control measures:
(i) A detailed historical baseline inventory of NO
(A) This inventory must represent estimates of actual emissions based on monitoring data in accordance with subpart H of part 75 of this chapter, if the source category is subject to monitoring requirements in accordance with subpart H of part 75 of this chapter.
(B) In the absence of monitoring data in accordance with subpart H of part 75 of this chapter, actual emissions must be quantified, to the maximum extent practicable, with the same degree of assurance with which emissions are quantified for sources subject to subpart H of part 75 of this chapter and using source-specific or source-category-specific assumptions that ensure a source’s or source category’s actual emissions are not overestimated. If a State uses factors to estimate emissions, production or utilization, or effectiveness of controls or rules for a source category, such factors must be chosen to ensure that emissions are not overestimated.
(C) For measures to reduce emissions from motor vehicles, emission estimates must be based on an emissions model that has been approved by EPA for use in SIP development and must be consistent with the planning assumptions regarding vehicle miles traveled and other factors current at the time of the SIP development.
(D) For measures to reduce emissions from nonroad engines or vehicles, emission estimates methodologies must be approved by EPA.
(ii) A detailed baseline inventory of NO
(A) These inventories must account for implementation of any control measures that are otherwise required by final rules already promulgated, as of May 12, 2005, or adopted or implemented by any federal agency, as of the date of submission of the SIP revision by the State to EPA, and must exclude any control measures specified in the SIP revision to meet the NO
(B) Economic and population forecasts must be as specific as possible to the applicable industry, State, and county of the source or source category and must be consistent with both national projections and relevant official planning assumptions, including estimates of population and vehicle miles traveled developed through consultation between State and local transportation and air quality agencies. However, if these official planning assumptions are inconsistent with official U.S. Census projections of population or with energy consumption projections contained in the U.S. Department of Energy’s most recent Annual Energy Outlook, then the SIP revision must make adjustments to correct the inconsistency or must demonstrate how the official planning assumptions are more accurate.
(C) These inventories must account for any changes in production method, materials, fuels, or efficiency that are expected to occur between the historical baseline year and 2009 or 2015, as appropriate.
(iii) A projection of NO
(A) These inventories must address the possibility that the State’s new control measures may cause production or utilization, and emissions, to shift to unregulated or less stringently regulated sources in the source category in the same or another State, and these inventories must include any such amounts of emissions that may shift to such other sources.
(B) The State must provide EPA with a summary of the computations, assumptions, and judgments used to determine the degree of reduction in projected 2009 and 2015 NO
(iv) The result of subtracting the amounts in paragraph (g)(2)(iii) of this section for 2009 and 2015, respectively, from the lower of the amounts in paragraph (g)(2)(i) or (g)(2)(ii) of this section for 2009 and 2015, respectively, may be credited towards the State’s Annual Non-EGU NO
(v) Each SIP revision must identify the sources of the data used in each estimate and each projection of emissions.
(h) Each SIP revision must comply with § 51.116 (regarding data availability).
(i) Each SIP revision must provide for monitoring the status of compliance with any control measures adopted to meet the State’s requirements under paragraph (e) of this section as follows:
(1) The SIP revision must provide for legally enforceable procedures for requiring owners or operators of stationary sources to maintain records of, and periodically report to the State:
(i) Information on the amount of NO
(ii) Other information as may be necessary to enable the State to determine whether the sources are in compliance with applicable portions of the control measures;
(2) The SIP revision must comply with § 51.212 (regarding testing, inspection, enforcement, and complaints);
(3) If the SIP revision contains any transportation control measures, then the SIP revision must comply with § 51.213 (regarding transportation control measures);
(4)(i) If the SIP revision contains measures to control EGUs, then the SIP revision must require such sources to comply with the monitoring, recordkeeping, and reporting provisions of subpart H of part 75 of this chapter.
(ii) If the SIP revision contains measures to control fossil fuel-fired non-EGUs that are boilers or combustion turbines with a maximum design heat input greater than 250 mmBtu/hr, then the SIP revision must require such sources to comply with the monitoring, recordkeeping, and reporting provisions of subpart H of part 75 of this chapter.
(iii) If the SIP revision contains measures to control any other non-EGUs that are not described in paragraph (i)(4)(ii) of this section, then the SIP revision must require such sources to comply with the monitoring, recordkeeping, and reporting provisions of subpart H of part 75 of this chapter, or the State must demonstrate why such requirements are not practicable and adopt alternative requirements that ensure that the required emissions reductions will be quantified, to the maximum extent practicable, with the same degree of assurance with which emissions are quantified for sources subject to subpart H of part 75 of this chapter.
(j) Each SIP revision must show that the State has legal authority to carry out the SIP revision, including authority to:
(1) Adopt emissions standards and limitations and any other measures necessary for attainment and maintenance of the State’s relevant Annual EGU NO
(2) Enforce applicable laws, regulations, and standards and seek injunctive relief;
(3) Obtain information necessary to determine whether air pollution sources are in compliance with applicable laws, regulations, and standards, including authority to require recordkeeping and to make inspections and conduct tests of air pollution sources; and
(4)(i) Require owners or operators of stationary sources to install, maintain, and use emissions monitoring devices and to make periodic reports to the State on the nature and amounts of emissions from such stationary sources; and
(ii) Make the data described in paragraph (j)(4)(i) of this section available to the public within a reasonable time after being reported and as correlated with any applicable emissions standards or limitations.
(k)(1) The provisions of law or regulation that the State determines provide the authorities required under this section must be specifically identified, and copies of such laws or regulations must be submitted with the SIP revision.
(2) Legal authority adequate to fulfill the requirements of paragraphs (j)(3) and (4) of this section may be delegated to the State under section 114 of the CAA.
(l)(1) A SIP revision may assign legal authority to local agencies in accordance with § 51.232.
(2) Each SIP revision must comply with § 51.240 (regarding general plan requirements).
(m) Each SIP revision must comply with § 51.280 (regarding resources).
(n) Each SIP revision must provide for State compliance with the reporting requirements in § 51.125.
(o)(1) Notwithstanding any other provision of this section, if a State adopts regulations substantively identical to subparts AA through II of part 96 of this chapter (CAIR NO
(2) If a State adopts an emissions trading program that differs substantively from subparts AA through II of part 96 of this chapter only as follows, then the emissions trading program is approved as set forth in paragraph (o)(1) of this section.
(i) The State may decline to adopt the CAIR NO
(A) Subpart II of this part and the provisions applicable only to CAIR NO
(B) Section 96.188(b) of this chapter and the provisions of subpart II of this part applicable only to CAIR NO
(C) Section 96.188(c) of this chapter and the provisions of subpart II of this part applicable only to CAIR NO
(ii) The State may decline to adopt the allocation provisions set forth in subpart EE of part 96 of this chapter and may instead adopt any methodology for allocating CAIR NO
(A) The State’s methodology must not allow the State to allocate CAIR NO
(B) The State’s methodology must require that, for EGUs commencing operation before January 1, 2001, the State will determine, and notify the Administrator of, each unit’s allocation of CAIR NO
(C) The State’s methodology must require that, for EGUs commencing operation on or after January 1, 2001, the State will determine, and notify the Administrator of, each unit’s allocation of CAIR NO
(D) The State’s methodology for allocating the compliance supplement pool must be substantively identical to § 97.143 (except that the permitting authority makes the allocations and the Administrator records the allocations made by the permitting authority) or otherwise in accordance with paragraph (e)(4) of this section.
(3) A State that adopts an emissions trading program in accordance with paragraph (o)(1) or (2) of this section is not required to adopt an emissions trading program in accordance with paragraph (aa)(1) or (2) of this section or § 96.124(o)(1) or (2).
(4) If a State adopts an emissions trading program that differs substantively from subparts AA through HH of part 96 of this chapter, other than as set forth in paragraph (o)(2) of this section, then such emissions trading program is not automatically approved as set forth in paragraph (o)(1) or (2) of this section and will be reviewed by the Administrator for approvability in accordance with the other provisions of this section, provided that the NO
(p) Notwithstanding any other provision of this section, a State may adopt, and include in a SIP revision submitted by March 31, 2007, regulations relating to the Federal CAIR NO
(1) The State may adopt, as CAIR NO
(i) Allocation provisions substantively identical to subpart EE of part 96 of this chapter, under which the permitting authority makes the allocations; or
(ii) Any methodology for allocating CAIR NO
(A) The State’s methodology must not allow the permitting authority to allocate CAIR NO
(B) The State’s methodology must require that, for EGUs commencing operation before January 1, 2001, the permitting authority will determine, and notify the Administrator of, each unit’s allocation of CAIR NO
(C) The State’s methodology must require that, for EGUs commencing operation on or after January 1, 2001, the permitting authority will determine, and notify the Administrator of, each unit’s allocation of CAIR NO
(2) The State may adopt, as compliance supplement pool provisions replacing the provisions in § 97.143 of this chapter:
(i) Provisions for allocating the State’s compliance supplement pool that are substantively identical to § 97.143 of this chapter, except that the permitting authority makes the allocations and the Administrator records the allocations made by the permitting authority;
(ii) Provisions for allocating the State’s compliance supplement pool that are substantively identical to § 96.143 of this chapter; or
(iii) Other provisions for allocating the State’s compliance supplement pool that are in accordance with paragraph (e)(4) of this section.
(3) The State may adopt CAIR opt-in unit provisions as follows:
(i) Provisions for CAIR opt-in units, including provisions for applications for CAIR opt-in permits, approval of CAIR opt-in permits, treatment of units as CAIR opt-in units, and allocation and recordation of CAIR NO
(ii) Provisions for CAIR opt-in units, including provisions for applications for CAIR opt-in permits, approval of CAIR opt-in permits, treatment of units as CAIR opt-in units, and allocation and recordation of CAIR NO
(iii) Provisions for applications for CAIR opt-in units, including provisions for CAIR opt-in permits, approval of CAIR opt-in permits, treatment of units as CAIR opt-in units, and allocation and recordation of CAIR NO
(q) The State’s SIP revision shall contain control measures and demonstrate that they will result in compliance with the State’s Ozone Season EGU NO
(1)(i) The Ozone Season EGU NO
(ii) The Ozone Season Non-EGU NO
(iii) If a State meets the requirements of paragraph (a)(2) of this section by imposing control measures on both EGUs and non-EGUs, then:
(A) The Ozone Season Non-EGU NO
(B) The Ozone Season EGU NO
(2) For a State that complies with the requirements of paragraph (a)(2) of this section by imposing control measures on only EGUs, the amount of the Ozone Season EGU NO
State | Ozone season EGU NO | Ozone season EGU NO |
---|---|---|
Alabama | 32,182 | 26,818 |
Arkansas | 11,515 | 9,596 |
Connecticut | 2,559 | 2,559 |
Delaware | 2,226 | 1,855 |
District of Columbia | 112 | 94 |
Florida | 47,912 | 39,926 |
Illinois | 30,701 | 28,981 |
Indiana | 45,952 | 39,273 |
Iowa | 14,263 | 11,886 |
Kentucky | 36,045 | 30,587 |
Louisiana | 17,085 | 14,238 |
Maryland | 12,834 | 10,695 |
Massachusetts | 7,551 | 6,293 |
Michigan | 28,971 | 24,142 |
Mississippi | 8,714 | 7,262 |
Missouri | 26,678 | 22,231 |
New Jersey | 6,654 | 5,545 |
New York | 20,632 | 17,193 |
North Carolina | 28,392 | 23,660 |
Ohio | 45,664 | 39,945 |
Pennsylvania | 42,171 | 35,143 |
South Carolina | 15,249 | 12,707 |
Tennessee | 22,842 | 19,035 |
Virginia | 15,994 | 13,328 |
West Virginia | 26,859 | 26,525 |
Wisconsin | 17,987 | 14,989 |
(3) For a State that complies with the requirements of paragraph (a)(2) of this section by imposing control measures on only non-EGUs, the amount of the Ozone Season Non-EGU NO
(4) Notwithstanding the State’s obligation to comply with paragraph (q)(2) or (3) of this section, the State’s SIP revision may allow sources required by the revision to implement NO
(r) Each SIP revision must set forth control measures to meet the amounts specified in paragraph (q) of this section, as applicable, including the following:
(1) A description of enforcement methods including, but not limited to:
(i) Procedures for monitoring compliance with each of the selected control measures;
(ii) Procedures for handling violations; and
(iii) A designation of agency responsibility for enforcement of implementation.
(2)(i) If a State elects to impose control measures on EGUs, then those measures must impose an ozone season NO
(ii) If a State elects to impose control measures on fossil fuel-fired non-EGUs that are boilers or combustion turbines with a maximum design heat input greater than 250 mmBtu/hr, then those measures must impose an ozone season NO
(iii) If a State elects to impose control measures on non-EGUs other than those described in paragraph (r)(2)(ii) of this section, then those measures must impose an ozone season NO
(s)(1) Each SIP revision that contains control measures covering non-EGUs as part or all of a State’s obligation in meeting its requirement under paragraph (a)(2) of this section must demonstrate that such control measures are adequate to provide for the timely compliance with the State’s Ozone Season Non-EGU NO
(2) The demonstration under paragraph (s)(1) of this section must include the following, with respect to each source category of non-EGUs for which the SIP revision requires control measures:
(i) A detailed historical baseline inventory of NO
(A) This inventory must represent estimates of actual emissions based on monitoring data in accordance with subpart H of part 75 of this chapter, if the source category is subject to monitoring requirements in accordance with subpart H of part 75 of this chapter.
(B) In the absence of monitoring data in accordance with subpart H of part 75 of this chapter, actual emissions must be quantified, to the maximum extent practicable, with the same degree of assurance with which emissions are quantified for sources subject to subpart H of part 75 of this chapter and using source-specific or source-category-specific assumptions that ensure a source’s or source category’s actual emissions are not overestimated. If a State uses factors to estimate emissions, production or utilization, or effectiveness of controls or rules for a source category, such factors must be chosen to ensure that emissions are not overestimated.
(C) For measures to reduce emissions from motor vehicles, emission estimates must be based on an emissions model that has been approved by EPA for use in SIP development and must be consistent with the planning assumptions regarding vehicle miles traveled and other factors current at the time of the SIP development.
(D) For measures to reduce emissions from nonroad engines or vehicles, emission estimates methodologies must be approved by EPA.
(ii) A detailed baseline inventory of NO
(A) These inventories must account for implementation of any control measures that are adopted or implemented by the State, as of May 12, 2005, or adopted or implemented by the federal government, as of the date of submission of the SIP revision by the State to EPA, and must exclude any control measures specified in the SIP revision to meet the NO
(B) Economic and population forecasts must be as specific as possible to the applicable industry, State, and county of the source or source category and must be consistent with both national projections and relevant official planning assumptions including estimates of population and vehicle miles traveled developed through consultation between State and local transportation and air quality agencies. However, if these official planning assumptions are inconsistent with official U.S. Census projections of population or with energy consumption projections contained in the U.S. Department of Energy’s most recent Annual Energy Outlook, then the SIP revision must make adjustments to correct the inconsistency or must demonstrate how the official planning assumptions are more accurate.
(C) These inventories must account for any changes in production method, materials, fuels, or efficiency that are expected to occur between the historical baseline ozone season and ozone season 2009 or ozone season 2015, as appropriate.
(iii) A projection of NO
(A) These inventories must address the possibility that the State’s new control measures may cause production or utilization, and emissions, to shift to unregulated or less stringently regulated sources in the source category in the same or another State, and these inventories must include any such amounts of emissions that may shift to such other sources.
(B) The State must provide EPA with a summary of the computations, assumptions, and judgments used to determine the degree of reduction in projected ozone season 2009 and ozone season 2015 NO
(iv) The result of subtracting the amounts in paragraph (s)(2)(iii) of this section for ozone season 2009 and ozone season 2015, respectively, from the lower of the amounts in paragraph (s)(2)(i) or (s)(2)(ii) of this section for ozone season 2009 and ozone season 2015, respectively, may be credited towards the State’s Ozone Season Non-EGU NO
(v) Each SIP revision must identify the sources of the data used in each estimate and each projection of emissions.
(t) Each SIP revision must comply with § 51.116 (regarding data availability).
(u) Each SIP revision must provide for monitoring the status of compliance with any control measures adopted to meet the State’s requirements under paragraph (q) of this section as follows:
(1) The SIP revision must provide for legally enforceable procedures for requiring owners or operators of stationary sources to maintain records of, and periodically report to the State:
(i) Information on the amount of NO
(ii) Other information as may be necessary to enable the State to determine whether the sources are in compliance with applicable portions of the control measures;
(2) The SIP revision must comply with § 51.212 (regarding testing, inspection, enforcement, and complaints);
(3) If the SIP revision contains any transportation control measures, then the SIP revision must comply with § 51.213 (regarding transportation control measures);
(4)(i) If the SIP revision contains measures to control EGUs, then the SIP revision must require such sources to comply with the monitoring, recordkeeping, and reporting provisions of subpart H of part 75 of this chapter.
(ii) If the SIP revision contains measures to control fossil fuel-fired non-EGUs that are boilers or combustion turbines with a maximum design heat input greater than 250 mmBtu/hr, then the SIP revision must require such sources to comply with the monitoring, recordkeeping, and reporting provisions of subpart H of part 75 of this chapter.
(iii) If the SIP revision contains measures to control any other non-EGUs that are not described in paragraph (u)(4)(ii) of this section, then the SIP revision must require such sources to comply with the monitoring, recordkeeping, and reporting provisions of subpart H of part 75 of this chapter, or the State must demonstrate why such requirements are not practicable and adopt alternative requirements that ensure that the required emissions reductions will be quantified, to the maximum extent practicable, with the same degree of assurance with which emissions are quantified for sources subject to subpart H of part 75 of this chapter.
(v) Each SIP revision must show that the State has legal authority to carry out the SIP revision, including authority to:
(1) Adopt emissions standards and limitations and any other measures necessary for attainment and maintenance of the State’s relevant Ozone Season EGU NO
(2) Enforce applicable laws, regulations, and standards and seek injunctive relief;
(3) Obtain information necessary to determine whether air pollution sources are in compliance with applicable laws, regulations, and standards, including authority to require recordkeeping and to make inspections and conduct tests of air pollution sources; and
(4)(i) Require owners or operators of stationary sources to install, maintain, and use emissions monitoring devices and to make periodic reports to the State on the nature and amounts of emissions from such stationary sources; and
(ii) Make the data described in paragraph (v)(4)(i) of this section available to the public within a reasonable time after being reported and as correlated with any applicable emissions standards or limitations.
(w)(1) The provisions of law or regulation that the State determines provide the authorities required under this section must be specifically identified, and copies of such laws or regulations must be submitted with the SIP revision.
(2) Legal authority adequate to fulfill the requirements of paragraphs (v)(3) and (4) of this section may be delegated to the State under section 114 of the CAA.
(x)(1) A SIP revision may assign legal authority to local agencies in accordance with § 51.232.
(2) Each SIP revision must comply with § 51.240 (regarding general plan requirements).
(y) Each SIP revision must comply with § 51.280 (regarding resources).
(z) Each SIP revision must provide for State compliance with the reporting requirements in § 51.125.
(aa)(1) Notwithstanding any other provision of this section, if a State adopts regulations substantively identical to subparts AAAA through IIII of part 96 of this chapter (CAIR Ozone Season NO
(2) If a State adopts an emissions trading program that differs substantively from subparts AAAA through IIII of part 96 of this chapter only as follows, then the emissions trading program is approved as set forth in paragraph (aa)(1) of this section.
(i) The State may expand the applicability provisions in § 96.304 to include all non-EGUs subject to the State’s emissions trading program approved under § 51.121(p).
(ii) The State may decline to adopt the CAIR NO
(A) Subpart IIII of this part and the provisions applicable only to CAIR NO
(B) Section 96.388(b) of this chapter and the provisions of subpart IIII of this part applicable only to CAIR NO
(C) Section 96.388(c) of this chapter and the provisions of subpart IIII of this part applicable only to CAIR NO
(iii) The State may decline to adopt the allocation provisions set forth in subpart EEEE of part 96 of this chapter and may instead adopt any methodology for allocating CAIR NO
(A) The State may provide for issuance of an amount of CAIR Ozone Season NO
(B) The State’s methodology must not allow the State to allocate CAIR Ozone Season NO
(C) The State’s methodology must require that, for EGUs commencing operation before January 1, 2001, the State will determine, and notify the Administrator of, each unit’s allocation of CAIR NO
(D) The State’s methodology must require that, for EGUs commencing operation on or after January 1, 2001, the State will determine, and notify the Administrator of, each unit’s allocation of CAIR Ozone Season NO
(3) A State that adopts an emissions trading program in accordance with paragraph (aa)(1) or (2) of this section is not required to adopt an emissions trading program in accordance with paragraph (o)(1) or (2) of this section or § 51.153(o)(1) or (2).
(4) If a State adopts an emissions trading program that differs substantively from subparts AAAA through IIII of part 96 of this chapter, other than as set forth in paragraph (aa)(2) of this section, then such emissions trading program is not automatically approved as set forth in paragraph (aa)(1) or (2) of this section and will be reviewed by the Administrator for approvability in accordance with the other provisions of this section, provided that the NO
(bb)(1)(i) The State may revise its SIP to provide that, for each ozone season during which a State implements control measures on EGUs or non-EGUs through an emissions trading program approved under paragraph (aa)(1) or (2) of this section, such EGUs and non-EGUs shall not be subject to the requirements of the State’s SIP meeting the requirements of § 51.121, if the State meets the requirement in paragraph (bb)(1)(ii) of this section.
(ii) For a State under paragraph (bb)(1)(i) of this section, if the State’s amount of tons specified in paragraph (q)(2) of this section exceeds the State’s amount of NO
(2) Rhode Island may revise its SIP to provide that, for each ozone season during which Rhode Island implements control measures on EGUs and non-EGUs through an emissions trading program adopted in regulations that differ substantively from subparts AAAA through IIII of part 96 of this chapter as set forth in this paragraph, such EGUs and non-EGUs shall not be subject to the requirements of the State’s SIP meeting the requirements of § 51.121.
(i) Rhode Island must expand the applicability provisions in § 96.304 to include all non-EGUs subject to Rhode Island’s emissions trading program approved under § 51.121(p).
(ii) Rhode Island may decline to adopt the CAIR NO
(A) Subpart IIII of this part and the provisions applicable only to CAIR NO
(B) Section 96.388(b) of this chapter and the provisions of subpart IIII of this part applicable only to CAIR NO
(C) Section 96.388(c) of this chapter and the provisions of subpart IIII of this part applicable only to CAIR NO
(iii) Rhode Island may adopt the allocation provisions set forth in subpart EEEE of part 96 of this chapter, provided that Rhode Island must provide for issuance of an amount of CAIR Ozone Season NO
(iv) Rhode Island may adopt any methodology for allocating CAIR NO
(A) Rhode Island’s methodology must not allow Rhode Island to allocate CAIR Ozone Season NO
(B) Rhode Island’s methodology must require that, for EGUs commencing operation before January 1, 2001, Rhode Island will determine, and notify the Administrator of, each unit’s allocation of CAIR NO
(C) Rhode Island’s methodology must require that, for EGUs commencing operation on or after January 1, 2001, Rhode Island will determine, and notify the Administrator of, each unit’s allocation of CAIR Ozone Season NO
(3) Notwithstanding a SIP revision by a State authorized under paragraph (bb)(1) of this section or by Rhode Island under paragraph (bb)(2) of this section, if the State’s or Rhode Island’s SIP that, without such SIP revision, imposes control measures on EGUs or non-EGUs under § 51.121 is determined by the Administrator to meet the requirements of § 51.121, such SIP shall be deemed to continue to meet the requirements of § 51.121.
(cc) The terms used in this section shall have the following meanings:
Administrator means the Administrator of the United States Environmental Protection Agency or the Administrator’s duly authorized representative.
Allocate or allocation means, with regard to allowances, the determination of the amount of allowances to be initially credited to a source or other entity.
Biomass means—
(1) Any organic material grown for the purpose of being converted to energy;
(2) Any organic byproduct of agriculture that can be converted into energy; or
(3) Any material that can be converted into energy and is nonmerchantable for other purposes, that is segregated from other nonmerchantable material, and that is;
(i) A forest-related organic resource, including mill residues, precommercial thinnings, slash, brush, or byproduct from conversion of trees to merchantable material; or
(ii) A wood material, including pallets, crates, dunnage, manufacturing and construction materials (other than pressure-treated, chemically-treated, or painted wood products), and landscape or right-of-way tree trimmings.
Boiler means an enclosed fossil- or other-fuel-fired combustion device used to produce heat and to transfer heat to recirculating water, steam, or other medium.
Bottoming-cycle cogeneration unit means a cogeneration unit in which the energy input to the unit is first used to produce useful thermal energy and at least some of the reject heat from the useful thermal energy application or process is then used for electricity production.
Clean Air Act or CAA means the Clean Air Act, 42 U.S.C. 7401, et seq.
Cogeneration unit means a stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired combustion turbine:
(1) Having equipment used to produce electricity and useful thermal energy for industrial, commercial, heating, or cooling purposes through the sequential use of energy; and
(2) Producing during the 12-month period starting on the date the unit first produces electricity and during any calendar year after the calendar year in which the unit first produces electricity—
(i) For a topping-cycle cogeneration unit,
(A) Useful thermal energy not less than 5 percent of total energy output; and
(B) Useful power that, when added to one-half of useful thermal energy produced, is not less then 42.5 percent of total energy input, if useful thermal energy produced is 15 percent or more of total energy output, or not less than 45 percent of total energy input, if useful thermal energy produced is less than 15 percent of total energy output.
(ii) For a bottoming-cycle cogeneration unit, useful power not less than 45 percent of total energy input;
(3) Provided that the total energy input under paragraphs (2)(i)(B) and (2)(ii) of this definition shall equal the unit’s total energy input from all fuel except biomass if the unit is a boiler.
Combustion turbine means:
(1) An enclosed device comprising a compressor, a combustor, and a turbine and in which the flue gas resulting from the combustion of fuel in the combustor passes through the turbine, rotating the turbine; and
(2) If the enclosed device under paragraph (1) of this definition is combined cycle, any associated duct burner, heat recovery steam generator, and steam turbine.
Commence operation means to have begun any mechanical, chemical, or electronic process, including, with regard to a unit, start-up of a unit’s combustion chamber.
Electric generating unit or EGU means:
(1)(i) Except as provided in paragraph (2) of this definition, a stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired combustion turbine serving at any time, since the later of November 15, 1990 or the start-up of the unit’s combustion chamber, a generator with nameplate capacity of more than 25 MWe producing electricity for sale.
(ii) If a stationary boiler or stationary combustion turbine that, under paragraph (1)(i) of this section, is not an electric generating unit begins to combust fossil fuel or to serve a generator with nameplate capacity of more than 25 MWe producing electricity for sale, the unit shall become an electric generating unit as provided in paragraph (1)(i) of this section on the first date on which it both combusts fossil fuel and serves such generator.
(2) A unit that meets the requirements set forth in paragraphs (2)(i)(A), (2)(ii)(A), or (2)(ii)(B) of this definition paragraph shall not be an electric generating unit:
(i)(A) Any unit that is an electric generating unit under paragraph (1)(i) or (ii) of this definition:
(1) Qualifying as a cogeneration unit during the 12-month period starting on the date the unit first produces electricity and continuing to qualify as a cogeneration unit; and
(2) Not serving at any time, since the later of November 15, 1990 or the start-up of the unit’s combustion chamber, a generator with nameplate capacity of more than 25 MWe supplying in any calendar year more than one-third of the unit’s potential electric output capacity or 219,000 MWh, whichever is greater, to any utility power distribution system for sale.
(B) If a unit qualifies as a cogeneration unit during the 12-month period starting on the date the unit first produces electricity and meets the requirements of paragraphs (2)(i)(A) of this section for at least one calendar year, but subsequently no longer meets all such requirements, the unit shall become an electric generating unit starting on the earlier of January 1 after the first calendar year during which the unit first no longer qualifies as a cogeneration unit or January 1 after the first calendar year during which the unit no longer meets the requirements of paragraph (2)(i)(A)(2) of this section.
(ii)(A) Any unit that is an electric generating unit under paragraph (1)(i) or (ii) of this definition commencing operation before January 1, 1985:
(1) Qualifying as a solid waste incineration unit; and
(2) With an average annual fuel consumption of non-fossil fuel for 1985–1987 exceeding 80 percent (on a Btu basis) and an average annual fuel consumption of non-fossil fuel for any 3 consecutive calendar years after 1990 exceeding 80 percent (on a Btu basis).
(B) Any unit that is an electric generating unit under paragraph (1)(i) or (ii) of this definition commencing operation on or after January 1, 1985:
(1) Qualifying as a solid waste incineration unit; and
(2) With an average annual fuel consumption of non-fossil fuel for the first 3 calendar years of operation exceeding 80 percent (on a Btu basis) and an average annual fuel consumption of non-fossil fuel for any 3 consecutive calendar years after 1990 exceeding 80 percent (on a Btu basis).
(C) If a unit qualifies as a solid waste incineration unit and meets the requirements of paragraph (2)(ii)(A) or (B) of this section for at least 3 consecutive calendar years, but subsequently no longer meets all such requirements, the unit shall become an electric generating unit starting on the earlier of January 1 after the first calendar year during which the unit first no longer qualifies as a solid waste incineration unit or January 1 after the first 3 consecutive calendar years after 1990 for which the unit has an average annual fuel consumption of fossil fuel of 20 percent or more.
Fossil fuel means natural gas, petroleum, coal, or any form of solid, liquid, or gaseous fuel derived from such material.
Fossil-fuel-fired means, with regard to a unit, combusting any amount of fossil fuel in any calendar year.
Generator means a device that produces electricity.
Maximum design heat input means the maximum amount of fuel per hour (in Btu/hr) that a unit is capable of combusting on a steady state basis as of the initial installation of the unit as specified by the manufacturer of the unit.
NAAQS means National Ambient Air Quality Standard.
Nameplate capacity means, starting from the initial installation of a generator, the maximum electrical generating output (in MWe) that the generator is capable of producing on a steady state basis and during continuous operation (when not restricted by seasonal or other deratings) as of such installation as specified by the manufacturer of the generator or, starting from the completion of any subsequent physical change in the generator resulting in an increase in the maximum electrical generating output (in MWe) that the generator is capable of producing on a steady state basis and during continuous operation (when not restricted by seasonal or other deratings), such increased maximum amount as of such completion as specified by the person conducting the physical change.
Non-EGU means a source of NO
NO
NO
Ozone season means the period, which begins May 1 and ends September 30 of any year.
Potential electrical output capacity means 33 percent of a unit’s maximum design heat input, divided by 3,413 Btu/kWh, divided by 1,000 kWh/MWh, and multiplied by 8,760 hr/yr.
Sequential use of energy means:
(1) For a topping-cycle cogeneration unit, the use of reject heat from electricity production in a useful thermal energy application or process; or
(2) For a bottoming-cycle cogeneration unit, the use of reject heat from useful thermal energy application or process in electricity production.
Solid waste incineration unit means a stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired combustion turbine that is a “solid waste incineration unit” as defined in section 129(g)(1) of the Clean Air Act.
Topping-cycle cogeneration unit means a cogeneration unit in which the energy input to the unit is first used to produce useful power, including electricity, and at least some of the reject heat from the electricity production is then used to provide useful thermal energy.
Total energy input means, with regard to a cogeneration unit, total energy of all forms supplied to the cogeneration unit, excluding energy produced by the cogeneration unit itself. Each form of energy supplied shall be measured by the lower heating value of that form of energy calculated as follows:
Total energy output means, with regard to a cogeneration unit, the sum of useful power and useful thermal energy produced by the cogeneration unit.
Unit means a stationary, fossil-fuel-fired boiler or a stationary, fossil-fuel-fired combustion turbine.
Useful power means, with regard to a cogeneration unit, electricity or mechanical energy made available for use, excluding any such energy used in the power production process (which process includes, but is not limited to, any on-site processing or treatment of fuel combusted at the unit and any on-site emission controls).
Useful thermal energy means, with regard to a cogeneration unit, thermal energy that is:
(1) Made available to an industrial or commercial process, excluding any heat contained in condensate return or makeup water;
(2) Used in a heating application (e.g., space heating or domestic hot water heating); or
(3) Used in a space cooling application (i.e., thermal energy used by an absorption chiller).
Utility power distribution system means the portion of an electricity grid owned or operated by a utility and dedicated to delivering electricity to customers.
(dd) New Hampshire may revise its SIP to implements control measures on EGUs and non-EGUs through an emissions trading program adopted in regulations that differ substantively from subparts AAAA through IIII of part 96 of this chapter as set forth in this paragraph.
(1) New Hampshire must expand the applicability provisions in § 96.304 of this chapter to include all non-EGUs subject to New Hampshire’s emissions trading program at New Hampshire Code of Administrative Rules, chapter Env-A 3200 (2004).
(2) New Hampshire may decline to adopt the CAIR NO
(i) Subpart IIII of this part and the provisions applicable only to CAIR NO
(ii) Section 96.388(b) of this chapter and the provisions of subpart IIII of this part applicable only to CAIR NO
(iii) Section 96.388(c) of this chapter and the provisions of subpart IIII of this part applicable only to CAIR NO
(3) New Hampshire may adopt the allocation provisions set forth in subpart EEEE of part 96 of this chapter, provided that New Hampshire must provide for issuance of an amount of CAIR Ozone Season NO
(4) New Hampshire may adopt any methodology for allocating CAIR NO
(i) New Hampshire’s methodology must not allow New Hampshire to allocate CAIR Ozone Season NO
(ii) New Hampshire’s methodology must require that, for EGUs commencing operation before January 1, 2001, New Hampshire will determine, and notify the Administrator of, each unit’s allocation of CAIR NO
(iii) New Hampshire’s methodology must require that, for EGUs commencing operation on or after January 1, 2001, New Hampshire will determine, and notify the Administrator of, each unit’s allocation of CAIR Ozone Season NO
(ee) Notwithstanding any other provision of this section, a State may adopt, and include in a SIP revision submitted by March 31, 2007, regulations relating to the Federal CAIR NO
(1) The State may adopt, as applicability provisions replacing the provisions in § 97.304 of this chapter, provisions for applicability that are substantively identical to the provisions in § 96.304 of this chapter expanded to include all non-EGUs subject to the State’s emissions trading program approved under § 51.121(p). Before January 1, 2009, a State’s applicability provisions shall be considered to be substantively identical to § 96.304 of this chapter (with the expansion allowed under this paragraph) regardless of whether the State’s regulations include the definition of “Biomass”, paragraph (3) of the definition of “Cogeneration unit”, and the second sentence of the definition of “Total energy input” in § 97.102 of this chapter promulgated on October 19, 2007, provided that the State timely submits to the Administrator a SIP revision that revises the State’s regulations to include such provisions. Submission to the Administrator of a SIP revision that revises the State’s regulations to include such provisions shall be considered timely if the submission is made by January 1, 2009.
(2) The State may adopt, as CAIR NO
(i) Allocation provisions substantively identical to subpart EEEE of part 96 of this chapter, under which the permitting authority makes the allocations; or
(ii) Any methodology for allocating CAIR NO
(A) The State may provide for issuance of an amount of CAIR Ozone Season NO
(B) The State’s methodology must not allow the State to allocate CAIR Ozone Season NO
(C) The State’s methodology must require that, for EGUs commencing operation before January 1, 2001, the permitting authority will determine, and notify the Administrator of, each unit’s allocation of CAIR NO
(D) The State’s methodology must require that, for EGUs commencing operation on or after January 1, 2001, the permitting authority will determine, and notify the Administrator of, each unit’s allocation of CAIR NO
(3) The State may adopt CAIR opt-in unit provisions as follows:
(i) Provisions for CAIR opt-in units, including provisions for applications for CAIR opt-in permits, approval of CAIR opt-in permits, treatment of units as CAIR opt-in units, and allocation and recordation of CAIR NO
(ii) Provisions for CAIR opt-in units, including provisions for applications for CAIR opt-in permits, approval of CAIR opt-in permits, treatment of units as CAIR opt-in units, and allocation and recordation of CAIR NO
(iii) Provisions for applications for CAIR opt-in units, including provisions for CAIR opt-in permits, approval of CAIR opt-in permits, treatment of units as CAIR opt-in units, and allocation and recordation of CAIR NO
(ff) Notwithstanding any provisions of paragraphs (a) through (ee) of this section, subparts AA through II and AAAA through IIII of part 96 of this chapter, subparts AA through II and AAAA through IIII of part 97 of this chapter, and any State’s SIP to the contrary:
(1) With regard to any control period that begins after December 31, 2014, the Administrator:
(i) Rescinds the determination in paragraph (a) of this section that the States identified in paragraph (c) of this section must submit a SIP revision with respect to the fine particles (PM
(ii) Will not carry out any of the functions set forth for the Administrator in subparts AA through II and AAAA through IIII of part 96 of this chapter, subparts AA through II and AAAA through IIII of part 97 of this chapter, or in any emissions trading program provisions in a State’s SIP approved under this section;
(2) The Administrator will not deduct for excess emissions any CAIR NO
(3) By March 3, 2015, the Administrator will remove from the CAIR NO
(4) By March 3, 2015, the Administrator will remove from the CAIR NO
§ 51.124 Findings and requirements for submission of State implementation plan revisions relating to emissions of sulfur dioxide pursuant to the Clean Air Interstate Rule.
(a)(1) Under section 110(a)(1) of the CAA, 42 U.S.C. 7410(a)(1), the Administrator determines that each State identified in paragraph (c) of this section must submit a SIP revision to comply with the requirements of section 110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 7410(a)(2)(D)(i)(I), through the adoption of adequate provisions prohibiting sources and other activities from emitting SO
(2) Notwithstanding the other provisions of this section, such provisions are not applicable as they relate to the State of Minnesota as of December 3, 2009.
(b) For each State identified in paragraph (c) of this section, the SIP revision required under paragraph (a) of this section will contain adequate provisions, for purposes of complying with section 110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 7410(a)(2)(D)(i)(I), only if the SIP revision contains control measures that assure compliance with the applicable requirements of this section.
(c) The following States are subject to the requirements of this section: Alabama, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, West Virginia, Wisconsin, and the District of Columbia.
(d)(1) The SIP revision under paragraph (a) of this section must be submitted to EPA by no later than September 11, 2006.
(2) The requirements of appendix V to this part shall apply to the SIP revision under paragraph (a) of this section.
(3) The State shall deliver 5 copies of the SIP revision under paragraph (a) of this section to the appropriate Regional Office, with a letter giving notice of such action.
(e) The State’s SIP revision shall contain control measures and demonstrate that they will result in compliance with the State’s Annual EGU SO
(1)(i) The Annual EGU SO
(ii) The Annual Non-EGU SO
(iii) If a State meets the requirements of paragraph (a) of this section by imposing control measures on both EGUs and non-EGUs, then:
(A) The Annual Non-EGU SO
(B) The Annual EGU SO
(2) For a State that complies with the requirements of paragraph (a) of this section by imposing control measures on only EGUs, the amount of the Annual EGU SO
State | Annual EGU SO | Annual EGU SO |
---|---|---|
Alabama | 157,582 | 110,307 |
Delaware | 22,411 | 15,687 |
District of Columbia | 708 | 495 |
Florida | 253,450 | 177,415 |
Georgia | 213,057 | 149,140 |
Illinois | 192,671 | 134,869 |
Indiana | 254,599 | 178,219 |
Iowa | 64,095 | 44,866 |
Kentucky | 188,773 | 132,141 |
Louisiana | 59,948 | 41,963 |
Maryland | 70,697 | 49,488 |
Michigan | 178,605 | 125,024 |
Minnesota | 49,987 | 34,991 |
Mississippi | 33,763 | 23,634 |
Missouri | 137,214 | 96,050 |
New Jersey | 32,392 | 22,674 |
New York | 135,139 | 94,597 |
North Carolina | 137,342 | 96,139 |
Ohio | 333,520 | 233,464 |
Pennsylvania | 275,990 | 193,193 |
South Carolina | 57,271 | 40,089 |
Tennessee | 137,216 | 96,051 |
Texas | 320,946 | 224,662 |
Virginia | 63,478 | 44,435 |
West Virginia | 215,881 | 151,117 |
Wisconsin | 87,264 | 61,085 |
(3) For a State that complies with the requirements of paragraph (a) of this section by imposing control measures on only non-EGUs, the amount of the Annual Non-EGU SO
(f) Each SIP revision must set forth control measures to meet the amounts specified in paragraph (e) of this section, as applicable, including the following:
(1) A description of enforcement methods including, but not limited to:
(i) Procedures for monitoring compliance with each of the selected control measures;
(ii) Procedures for handling violations; and
(iii) A designation of agency responsibility for enforcement of implementation.
(2)(i) If a State elects to impose control measures on EGUs, then those measures must impose an annual SO
(ii) If a State elects to impose control measures on fossil fuel-fired non-EGUs that are boilers or combustion turbines with a maximum design heat input greater than 250 mmBtu/hr, then those measures must impose an annual SO
(iii) If a State elects to impose control measures on non-EGUs other than those described in paragraph (f)(2)(ii) of this section, then those measures must impose an annual SO
(g)(1) Each SIP revision that contains control measures covering non-EGUs as part or all of a State’s obligation in meeting its requirement under paragraph (a) of this section must demonstrate that such control measures are adequate to provide for the timely compliance with the State’s Annual Non-EGU SO
(2) The demonstration under paragraph (g)(1) of this section must include the following, with respect to each source category of non-EGUs for which the SIP revision requires control measures:
(i) A detailed historical baseline inventory of SO
(A) This inventory must represent estimates of actual emissions based on monitoring data in accordance with part 75 of this chapter, if the source category is subject to part 75 monitoring requirements in accordance with part 75 of this chapter.
(B) In the absence of monitoring data in accordance with part 75 of this chapter, actual emissions must be quantified, to the maximum extent practicable, with the same degree of assurance with which emissions are quantified for sources subject to part 75 of this chapter and using source-specific or source-category-specific assumptions that ensure a source’s or source category’s actual emissions are not overestimated. If a State uses factors to estimate emissions, production or utilization, or effectiveness of controls or rules for a source category, such factors must be chosen to ensure that emissions are not overestimated.
(C) For measures to reduce emissions from motor vehicles, emission estimates must be based on an emissions model that has been approved by EPA for use in SIP development and must be consistent with the planning assumptions regarding vehicle miles traveled and other factors current at the time of the SIP development.
(D) For measures to reduce emissions from nonroad engines or vehicles, emission estimates methodologies must be approved by EPA.
(ii) A detailed baseline inventory of SO
(A) These inventories must account for implementation of any control measures that are adopted or implemented by the State, as of May 12, 2005, or adopted or implemented by the federal government, as of the date of submission of the SIP revision by the State to EPA, and must exclude any control measures specified in the SIP revision to meet the SO
(B) Economic and population forecasts must be as specific as possible to the applicable industry, State, and county of the source or source category and must be consistent with both national projections and relevant official planning assumptions, including estimates of population and vehicle miles traveled developed through consultation between State and local transportation and air quality agencies. However, if these official planning assumptions are inconsistent with official U.S. Census projections of population or with energy consumption projections contained in the U.S. Department of Energy’s most recent Annual Energy Outlook, then the SIP revision must make adjustments to correct the inconsistency or must demonstrate how the official planning assumptions are more accurate.
(C) These inventories must account for any changes in production method, materials, fuels, or efficiency that are expected to occur between the historical baseline year and 2010 or 2015, as appropriate.
(iii) A projection of SO
(A) These inventories must address the possibility that the State’s new control measures may cause production or utilization, and emissions, to shift to unregulated or less stringently regulated sources in the source category in the same or another State, and these inventories must include any such amounts of emissions that may shift to such other sources.
(B) The State must provide EPA with a summary of the computations, assumptions, and judgments used to determine the degree of reduction in projected 2010 and 2015 SO
(iv) The result of subtracting the amounts in paragraph (g)(2)(iii) of this section for 2010 and 2015, respectively, from the lower of the amounts in paragraph (g)(2)(i) or (g)(2)(ii) of this section for 2010 and 2015, respectively, may be credited towards the State’s Annual Non-EGU SO
(v) Each SIP revision must identify the sources of the data used in each estimate and each projection of emissions.
(h) Each SIP revision must comply with § 51.116 (regarding data availability).
(i) Each SIP revision must provide for monitoring the status of compliance with any control measures adopted to meet the State’s requirements under paragraph (e) of this section, as follows:
(1) The SIP revision must provide for legally enforceable procedures for requiring owners or operators of stationary sources to maintain records of, and periodically report to the State:
(i) Information on the amount of SO
(ii) Other information as may be necessary to enable the State to determine whether the sources are in compliance with applicable portions of the control measures;
(2) The SIP revision must comply with § 51.212 (regarding testing, inspection, enforcement, and complaints);
(3) If the SIP revision contains any transportation control measures, then the SIP revision must comply with § 51.213 (regarding transportation control measures);
(4)(i) If the SIP revision contains measures to control EGUs, then the SIP revision must require such sources to comply with the monitoring, recordkeeping, and reporting provisions of part 75 of this chapter.
(ii) If the SIP revision contains measures to control fossil fuel-fired non-EGUs that are boilers or combustion turbines with a maximum design heat input greater than 250 mmBtu/hr, then the SIP revision must require such sources to comply with the monitoring, recordkeeping, and reporting provisions of part 75 of this chapter.
(iii) If the SIP revision contains measures to control any other non-EGUs that are not described in paragraph (i)(4)(ii) of this section, then the SIP revision must require such sources to comply with the monitoring, recordkeeping, and reporting provisions of part 75 of this chapter, or the State must demonstrate why such requirements are not practicable and adopt alternative requirements that ensure that the required emissions reductions will be quantified, to the maximum extent practicable, with the same degree of assurance with which emissions are quantified for sources subject to part 75 of this chapter.
(j) Each SIP revision must show that the State has legal authority to carry out the SIP revision, including authority to:
(1) Adopt emissions standards and limitations and any other measures necessary for attainment and maintenance of the State’s relevant Annual EGU SO
(2) Enforce applicable laws, regulations, and standards and seek injunctive relief;
(3) Obtain information necessary to determine whether air pollution sources are in compliance with applicable laws, regulations, and standards, including authority to require recordkeeping and to make inspections and conduct tests of air pollution sources; and
(4)(i) Require owners or operators of stationary sources to install, maintain, and use emissions monitoring devices and to make periodic reports to the State on the nature and amounts of emissions from such stationary sources; and
(ii) Make the data described in paragraph (j)(4)(i) of this section available to the public within a reasonable time after being reported and as correlated with any applicable emissions standards or limitations.
(k)(1) The provisions of law or regulation that the State determines provide the authorities required under this section must be specifically identified, and copies of such laws or regulations must be submitted with the SIP revision.
(2) Legal authority adequate to fulfill the requirements of paragraphs (j)(3) and (4) of this section may be delegated to the State under section 114 of the CAA.
(l)(1) A SIP revision may assign legal authority to local agencies in accordance with § 51.232.
(2) Each SIP revision must comply with § 51.240 (regarding general plan requirements).
(m) Each SIP revision must comply with § 51.280 (regarding resources).
(n) Each SIP revision must provide for State compliance with the reporting requirements in § 51.125.
(o)(1) Notwithstanding any other provision of this section, if a State adopts regulations substantively identical to subparts AAA through III of part 96 of this chapter (CAIR SO
(2) If a State adopts an emissions trading program that differs substantively from subparts AAA through III of part 96 of this chapter only as follows, then the emissions trading program is approved as set forth in paragraph (o)(1) of this section.
(i) The State may decline to adopt the CAIR SO
(ii) The State may decline to adopt the CAIR SO
(iii) The State may decline to adopt the CAIR SO
(3) A State that adopts an emissions trading program in accordance with paragraph (o)(1) or (2) of this section is not required to adopt an emissions trading program in accordance with § 96.123 (o)(1) or (2) or (aa)(1) or (2) of this chapter.
(4) If a State adopts an emissions trading program that differs substantively from subparts AAA through III of part 96 of this chapter, other than as set forth in paragraph (o)(2) of this section, then such emissions trading program is not automatically approved as set forth in paragraph (o)(1) or (2) of this section and will be reviewed by the Administrator for approvability in accordance with the other provisions of this section, provided that the SO
(p) If a State’s SIP revision does not contain an emissions trading program approved under paragraph (o)(1) or (2) of this section but contains control measures on EGUs as part or all of a State’s obligation in meeting its requirement under paragraph (a) of this section:
(1) The SIP revision shall provide, for each year that the State has such obligation, for the permanent retirement of an amount of Acid Rain allowances allocated to sources in the State for that year and not deducted by the Administrator under the Acid Rain Program and any emissions trading program approved under paragraph (o)(1) or (2) of this section, equal to the difference between—
(A) The total amount of Acid Rain allowances allocated under the Acid Rain Program to the sources in the State for that year; and
(B) If the State’s SIP revision contains only control measures on EGUs, the State’s Annual EGU SO
(2) The SIP revision providing for permanent retirement of Acid Rain allowances under paragraph (p)(1) of this section must ensure that such allowances are not available for deduction by the Administrator under the Acid Rain Program and any emissions trading program approved under paragraph (o)(1) or (2) of this section.
(q) The terms used in this section shall have the following meanings:
Acid Rain allowance means a limited authorization issued by the Administrator under the Acid Rain Program to emit up to one ton of sulfur dioxide during the specified year or any year thereafter, except as otherwise provided by the Administrator.
Acid Rain Program means a multi-State sulfur dioxide and nitrogen oxides air pollution control and emissions reduction program established by the Administrator under title IV of the CAA and parts 72 through 78 of this chapter.
Administrator means the Administrator of the United States Environmental Protection Agency or the Administrator’s duly authorized representative.
Allocate or allocation means, with regard to allowances, the determination of the amount of allowances to be initially credited to a source or other entity.
Biomass means—
(1) Any organic material grown for the purpose of being converted to energy;
(2) Any organic byproduct of agriculture that can be converted into energy; or
(3) Any material that can be converted into energy and is nonmerchantable for other purposes, that is segregated from other nonmerchantable material, and that is;
(i) A forest-related organic resource, including mill residues, precommercial thinnings, slash, brush, or byproduct from conversion of trees to merchantable material; or
(ii) A wood material, including pallets, crates, dunnage, manufacturing and construction materials (other than pressure-treated, chemically-treated, or painted wood products), and landscape or right-of-way tree trimmings.
Boiler means an enclosed fossil- or other-fuel-fired combustion device used to produce heat and to transfer heat to recirculating water, steam, or other medium.
Bottoming-cycle cogeneration unit means a cogeneration unit in which the energy input to the unit is first used to produce useful thermal energy and at least some of the reject heat from the useful thermal energy application or process is then used for electricity production.
Clean Air Act or CAA means the Clean Air Act, 42 U.S.C. 7401, et seq.
Cogeneration unit means a stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired combustion turbine:
(1) Having equipment used to produce electricity and useful thermal energy for industrial, commercial, heating, or cooling purposes through the sequential use of energy; and
(2) Producing during the 12-month period starting on the date the unit first produces electricity and during any calendar year after the calendar year in which the unit first produces electricity—
(i) For a topping-cycle cogeneration unit,
(A) Useful thermal energy not less than 5 percent of total energy output; and
(B) Useful power that, when added to one-half of useful thermal energy produced, is not less then 42.5 percent of total energy input, if useful thermal energy produced is 15 percent or more of total energy output, or not less than 45 percent of total energy input, if useful thermal energy produced is less than 15 percent of total energy output.
(ii) For a bottoming-cycle cogeneration unit, useful power not less than 45 percent of total energy input;
(3) Provided that the total energy input under paragraphs (2)(i)(B) and (2)(ii) of this definition shall equal the unit’s total energy input from all fuel except biomass if the unit is a boiler.
Combustion turbine means:
(1) An enclosed device comprising a compressor, a combustor, and a turbine and in which the flue gas resulting from the combustion of fuel in the combustor passes through the turbine, rotating the turbine; and
(2) If the enclosed device under paragraph (1) of this definition is combined cycle, any associated duct burner, heat recovery steam generator, and steam turbine.
Commence operation means to have begun any mechanical, chemical, or electronic process, including, with regard to a unit, start-up of a unit’s combustion chamber.
Electric generating unit or EGU means:
(1)(i) Except as provided in paragraph (2) of this definition, a stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired combustion turbine serving at any time, since the later of November 15, 1990 or the start-up of the unit’s combustion chamber, a generator with nameplate capacity of more than 25 MWe producing electricity for sale.
(ii) If a stationary boiler or stationary combustion turbine that, under paragraph (1)(i) of this section, is not an electric generating unit begins to combust fossil fuel or to serve a generator with nameplate capacity of more than 25 MWe producing electricity for sale, the unit shall become an electric generating unit as provided in paragraph (1)(i) of this section on the first date on which it both combusts fossil fuel and serves such generator.
(2) A unit that meets the requirements set forth in paragraphs (2)(i)(A), (2)(ii)(A), or (2)(ii)(B) of this definition paragraph shall not be an electric generating unit:
(i)(A) Any unit that is an electric generating unit under paragraph (1)(i) or (ii) of this definition:
(1) Qualifying as a cogeneration unit during the 12-month period starting on the date the unit first produces electricity and continuing to qualify as a cogeneration unit; and
(2) Not serving at any time, since the later of November 15, 1990 or the start-up of the unit’s combustion chamber, a generator with nameplate capacity of more than 25 MWe supplying in any calendar year more than one-third of the unit’s potential electric output capacity or 219,000 MWh, whichever is greater, to any utility power distribution system for sale.
(B) If a unit qualifies as a cogeneration unit during the 12-month period starting on the date the unit first produces electricity and meets the requirements of paragraphs (2)(i)(A) of this section for at least one calendar year, but subsequently no longer meets all such requirements, the unit shall become an electric generating unit starting on the earlier of January 1 after the first calendar year during which the unit first no longer qualifies as a cogeneration unit or January 1 after the first calendar year during which the unit no longer meets the requirements of paragraph (2)(i)(A)(2) of this section.
(ii)(A) Any unit that is an electric generating unit under paragraph (1)(i) or (ii) of this definition commencing operation before January 1, 1985:
(1) Qualifying as a solid waste incineration unit; and
(2) With an average annual fuel consumption of non-fossil fuel for 1985–1987 exceeding 80 percent (on a Btu basis) and an average annual fuel consumption of non-fossil fuel for any 3 consecutive calendar years after 1990 exceeding 80 percent (on a Btu basis).
(B) Any unit that is an electric generating unit under paragraph (1)(i) or (ii) of this definition commencing operation on or after January 1, 1985:
(1) Qualifying as a solid waste incineration unit; and
(2) With an average annual fuel consumption of non-fossil fuel for the first 3 calendar years of operation exceeding 80 percent (on a Btu basis) and an average annual fuel consumption of non-fossil fuel for any 3 consecutive calendar years after 1990 exceeding 80 percent (on a Btu basis).
(C) If a unit qualifies as a solid waste incineration unit and meets the requirements of paragraph (2)(ii)(A) or (B) of this section for at least 3 consecutive calendar years, but subsequently no longer meets all such requirements, the unit shall become an electric generating unit starting on the earlier of January 1 after the first calendar year during which the unit first no longer qualifies as a solid waste incineration unit or January 1 after the first 3 consecutive calendar years after 1990 for which the unit has an average annual fuel consumption of fossil fuel of 20 percent or more.
Fossil fuel means natural gas, petroleum, coal, or any form of solid, liquid, or gaseous fuel derived from such material.
Fossil-fuel-fired means, with regard to a unit, combusting any amount of fossil fuel in any calendar year.
Generator means a device that produces electricity.
Maximum design heat input means the maximum amount of fuel per hour (in Btu/hr) that a unit is capable of combusting on a steady state basis as of the initial installation of the unit as specified by the manufacturer of the unit.
NAAQS means National Ambient Air Quality Standard.
Nameplate capacity means, starting from the initial installation of a generator, the maximum electrical generating output (in MWe) that the generator is capable of producing on a steady state basis and during continuous operation (when not restricted by seasonal or other deratings as of such installation as specified by the manufacturer of the generator or, starting from the completion of any subsequent physical change in the generator resulting in an increase in the maximum electrical generating output (in MWe) that the generator is capable of producing on a steady state basis and during continuous operation (when not restricted by seasonal or other deratings), such increased maximum amount as of such completion as specified by the person conducting the physical change.
Non-EGU means a source of SO
Potential electrical output capacity means 33 percent of a unit’s maximum design heat input, divided by 3,413 Btu/kWh, divided by 1,000 kWh/MWh, and multiplied by 8,760 hr/yr.
Sequential use of energy means:
(1) For a topping-cycle cogeneration unit, the use of reject heat from electricity production in a useful thermal energy application or process; or
(2) For a bottoming-cycle cogeneration unit, the use of reject heat from useful thermal energy application or process in electricity production.
Solid waste incineration unit means a stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired combustion turbine that is a “solid waste incineration unit” as defined in section 129(g)(1) of the Clean Air Act.
Topping-cycle cogeneration unit means a cogeneration unit in which the energy input to the unit is first used to produce useful power, including electricity, and at least some of the reject heat from the electricity production is then used to provide useful thermal energy.
Total energy input means, with regard to a cogeneration unit, total energy of all forms supplied to the cogeneration unit, excluding energy produced by the cogeneration unit itself.
Total energy output means, with regard to a cogeneration unit, the sum of useful power and useful thermal energy produced by the cogeneration unit. Each form of energy supplied shall be measured by the lower heating value of that form of energy calculated as follows:
Unit means a stationary, fossil-fuel-fired boiler or a stationary, fossil-fuel fired combustion turbine.
Useful power means, with regard to a cogeneration unit, electricity or mechanical energy made available for use, excluding any such energy used in the power production process (which process includes, but is not limited to, any on-site processing or treatment of fuel combusted at the unit and any on-site emission controls).
Useful thermal energy means, with regard to a cogeneration unit, thermal energy that is:
(1) Made available to an industrial or commercial process, excluding any heat contained in condensate return or makeup water;
(2) Used in a heating application (e.g., space heating or domestic hot water heating); or
(3) Used in a space cooling application (i.e., thermal energy used by an absorption chiller).
Utility power distribution system means the portion of an electricity grid owned or operated by a utility and dedicated to delivering electricity to customers.
(r) Notwithstanding any other provision of this section, a State may adopt, and include in a SIP revision submitted by March 31, 2007, regulations relating to the Federal CAIR SO
(1) Provisions for CAIR opt-in units, including provisions for applications for CAIR opt-in permits, approval of CAIR opt-in permits, treatment of units as CAIR opt-in units, and allocation and recordation of CAIR SO
(2) Provisions for CAIR opt-in units, including provisions for applications for CAIR opt-in permits, approval of CAIR opt-in permits, treatment of units as CAIR opt-in units, and allocation and recordation of CAIR SO
(3) Provisions for applications for CAIR opt-in units, including provisions for CAIR opt-in permits, approval of CAIR opt-in permits, treatment of units as CAIR opt-in units, and allocation and recordation of CAIR SO
(s) Notwithstanding any provisions of paragraphs (a) through (r) of this section, subparts AAA through III of part 96 of this chapter, subparts AAA through III of part 97 of this chapter, and any State’s SIP to the contrary:
(1) With regard to any control period that begins after December 31, 2014, the Administrator:
(i) Rescinds the determination in paragraph (a) of this section that the States identified in paragraph (c) of this section must submit a SIP revision with respect to the fine particles (PM
(ii) Will not carry out any of the functions set forth for the Administrator in subparts AAA through III of part 96 of this chapter, subparts AAA through III of part 97 of this chapter, or in any emissions trading program in a State’s SIP approved under this section; and
(2) The Administrator will not deduct for excess emissions any CAIR SO
§ 51.125 [Reserved]
§ 51.126 Determination of widespread use of ORVR and waiver of CAA section 182(b)(3) Stage II gasoline vapor recovery requirements.
(a) Pursuant to section 202(a)(6) of the Clean Air Act, the Administrator has determined that, effective May 16, 2012, onboard refueling vapor recovery (ORVR) systems are in widespread use in the motor vehicle fleet within the United States.
(b) Effective May 16, 2012, the Administrator waives the requirement of Clean Air Act section 182(b)(3) for Stage II vapor recovery systems in ozone nonattainment areas regardless of classification. States must submit and receive EPA approval of a revision to their approved State Implementation Plans before removing Stage II requirements that are contained therein.
Subpart H—Prevention of Air Pollution Emergency Episodes
§ 51.150 Classification of regions for episode plans.
(a) This section continues the classification system for episode plans. Each region is classified separately with respect to each of the following pollutants: Sulfur oxides, particulate matter, carbon monoxide, nitrogen dioxide, and ozone.
(b) Priority I Regions means any area with greater ambient concentrations than the following:
(1) Sulfur dioxide—100 µg/m
(2) Particulate matter—95 µg/m
(3) Carbon monoxide—55 mg/m
(4) Nitrogen dioxide—100 µg/m
(5) Ozone—195 µg/m
(c) Priority IA Region means any area which is Priority I primarily because of emissions from a single point source.
(d) Priority II Region means any area which is not a Priority I region and has ambient concentrations between the following:
(1) Sulfur Dioxides—60–100 µg/m
(2) Particulate matter—60–95 µg/m
(e) In the absence of adequate monitoring data, appropriate models must be used to classify an area under paragraph (b) of this section, consistent with the requirements contained in § 51.112(a).
(f) Areas which do not meet the above criteria are classified Priority III.
§ 51.151 Significant harm levels.
Each plan for a Priority I region must include a contingency plan which must, as a minimum, provide for taking action necessary to prevent ambient pollutant concentrations at any location in such region from reaching the following levels:
§ 51.152 Contingency plans.
(a) Each contingency plan must—
(1) Specify two or more stages of episode criteria such as those set forth in appendix L to this part, or their equivalent;
(2) Provide for public announcement whenever any episode stage has been determined to exist; and
(3) Specify adequate emission control actions to be taken at each episode stage. (Examples of emission control actions are set forth in appendix L.)
(b) Each contingency plan for a Priority I region must provide for the following:
(1) Prompt acquisition of forecasts of atmospheric stagnation conditions and of updates of such forecasts as frequently as they are issued by the National Weather Service.
(2) Inspection of sources to ascertain compliance with applicable emission control action requirements.
(3) Communications procedures for transmitting status reports and orders as to emission control actions to be taken during an episode stage, including procedures for contact with public officials, major emission sources, public health, safety, and emergency agencies and news media.
(c) Each plan for a Priority IA and II region must include a contingency plan that meets, as a minimum, the requirements of paragraphs (b)(1) and (b)(2) of this section. Areas classified Priority III do not need to develop episode plans.
(d) Notwithstanding the requirements of paragraphs (b) and (c) of this section, the Administrator may, at his discretion—
(1) Exempt from the requirements of this section those portions of Priority I, IA, or II regions which have been designated as attainment or unclassifiable for national primary and secondary standards under section 107 of the Act; or
(2) Limit the requirements pertaining to emission control actions in Priority I regions to—
(i) Urbanized areas as identified in the most recent United States Census, and
(ii) Major emitting facilities, as defined by section 169(1) of the Act, outside the urbanized areas.
§ 51.153 Reevaluation of episode plans.
(a) States should periodically reevaluate priority classifications of all Regions or portion of Regions within their borders. The reevaluation must consider the three most recent years of air quality data. If the evaluation indicates a change to a higher priority classification, appropriate changes in the episode plan must be made as expeditiously as practicable.
(b) [Reserved]
Subpart I—Review of New Sources and Modifications
§ 51.160 Legally enforceable procedures.
(a) Each plan must set forth legally enforceable procedures that enable the State or local agency to determine whether the construction or modification of a facility, building, structure or installation, or combination of these will result in—
(1) A violation of applicable portions of the control strategy; or
(2) Interference with attainment or maintenance of a national standard in the State in which the proposed source (or modification) is located or in a neighboring State.
(b) Such procedures must include means by which the State or local agency responsible for final decisionmaking on an application for approval to construct or modify will prevent such construction or modification if—
(1) It will result in a violation of applicable portions of the control strategy; or
(2) It will interfere with the attainment or maintenance of a national standard.
(c) The procedures must provide for the submission, by the owner or operator of the building, facility, structure, or installation to be constructed or modified, of such information on—
(1) The nature and amounts of emissions to be emitted by it or emitted by associated mobile sources;
(2) The location, design, construction, and operation of such facility, building, structure, or installation as may be necessary to permit the State or local agency to make the determination referred to in paragraph (a) of this section.
(d) The procedures must provide that approval of any construction or modification must not affect the responsibility to the owner or operator to comply with applicable portions of the control strategy.
(e) The procedures must identify types and sizes of facilities, buildings, structures, or installations which will be subject to review under this section. The plan must discuss the basis for determining which facilities will be subject to review.
(f) The procedures must discuss the air quality data and the dispersion or other air quality modeling used to meet the requirements of this subpart.
(1) All applications of air quality modeling involved in this subpart shall be based on the applicable models, data bases, and other requirements specified in appendix W of this part (Guideline on Air Quality Models).
(2) Where an air quality model specified in appendix W of this part (Guideline on Air Quality Models) is inappropriate, the model may be modified or another model substituted. Such a modification or substitution of a model may be made on a case-by-case basis or, where appropriate, on a generic basis for a specific State program. Written approval of the Administrator must be obtained for any modification or substitution. In addition, use of a modified or substituted model must be subject to notice and opportunity for public comment under procedures set forth in § 51.102.
§ 51.161 Public availability of information.
(a) The legally enforceable procedures in § 51.160 must also require the State or local agency to provide opportunity for public comment on information submitted by owners and operators. The public information must include the agency’s analysis of the effect of construction or modification on ambient air quality, including the agency’s proposed approval or disapproval.
(b) For purposes of paragraph (a) of this section, opportunity for public comment shall include, as a minimum—
(1) Availability for public inspection in at least one location in the area affected of the information submitted by the owner or operator and of the State or local agency’s analysis of the effect on air quality. This requirement may be met by making these materials available at a physical location or on a public Web site identified by the State or local agency;
(2) A 30-day period for submittal of public comment; and
(3) A notice by prominent advertisement in the area affected of the location of the source information and analysis specified in paragraph (b)(1) of this section.
(c) Where the 30-day comment period required in paragraph (b) of this section would conflict with existing requirements for acting on requests for permission to construct or modify, the State may submit for approval a comment period which is consistent with such existing requirements.
(d) A copy of the notice required by paragraph (b) of this section must also be sent to the Administrator through the appropriate Regional Office, and to all other State and local air pollution control agencies having jurisdiction in the region in which such new or modified installation will be located. The notice also must be sent to any other agency in the region having responsibility for implementing the procedures required under this subpart. For lead, a copy of the notice is required for all point sources. The definition of point for lead is given in § 51.100(k)(2).
§ 51.162 Identification of responsible agency.
Each plan must identify the State or local agency which will be responsible for meeting the requirements of this subpart in each area of the State. Where such responsibility rests with an agency other than an air pollution control agency, such agency will consult with the appropriate State or local air pollution control agency in carrying out the provisions of this subpart.
§ 51.163 Administrative procedures.
The plan must include the administrative procedures, which will be followed in making the determination specified in paragraph (a) of § 51.160.
§ 51.164 Stack height procedures.
Such procedures must provide that the degree of emission limitation required of any source for control of any air pollutant must not be affected by so much of any source’s stack height that exceeds good engineering practice or by any other dispersion technique, except as provided in § 51.118(b). Such procedures must provide that before a State issues a permit to a source based on a good engineering practice stack height that exceeds the height allowed by § 51.100(ii) (1) or (2), the State must notify the public of the availability of the demonstration study and must provide opportunity for public hearing on it. This section does not require such procedures to restrict in any manner the actual stack height of any source.
§ 51.165 Permit requirements.
(a) State Implementation Plan and Tribal Implementation Plan provisions satisfying sections 172(c)(5) and 173 of the Act shall meet the following conditions:
(1) All such plans shall use the specific definitions. Deviations from the following wording will be approved only if the State specifically demonstrates that the submitted definition is more stringent, or at least as stringent, in all respects as the corresponding definition below:
(i) Stationary source means any building, structure, facility, or installation which emits or may emit a regulated NSR pollutant.
(ii)(A) Building, structure, facility, or installation means all of the pollutant-emitting activities which belong to the same industrial grouping, are located on one or more contiguous or adjacent properties, and are under the control of the same person (or persons under common control) except the activities of any vessel. Pollutant emitting activities shall be considered as part of the same industrial grouping if they belong to the same Major Group (i.e., which have the same two-digit code) as described in the Standard Industrial Classification Manual, 1972, as amended by the 1977 Supplement (U.S. Government Printing Office stock numbers 4101–0065 and 003–005–00176–0, respectively).
(B) The plan may include the following provision: Notwithstanding the provisions of paragraph (a)(1)(ii)(A) of this section, building, structure, facility, or installation means, for onshore activities under Standard Industrial Classification (SIC) Major Group 13: Oil and Gas Extraction, all of the pollutant-emitting activities included in Major Group 13 that are located on one or more contiguous or adjacent properties, and are under the control of the same person (or persons under common control). Pollutant emitting activities shall be considered adjacent if they are located on the same surface site; or if they are located on surface sites that are located within