cfr_sections
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21 rows where part_number = 50 and title_number = 40 sorted by section_id
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| section_id ▼ | title_number | title_name | chapter | subchapter | part_number | part_name | subpart | subpart_name | section_number | section_heading | agency | authority | source_citation | amendment_citations | full_text |
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| 40:40:2.0.1.1.1.0.1.1 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.1 Definitions. | EPA | [36 FR 22384, Nov. 25, 1971, as amended at 41 FR 11253, Mar. 17, 1976; 48 FR 2529, Jan. 20, 1983; 63 FR 7274, Feb. 12, 1998; 72 FR 13580, Mar. 22, 2007; 81 FR 68276, Oct. 3, 2016] | (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… | |||||
| 40:40:2.0.1.1.1.0.1.10 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.10 National 8-hour primary and secondary ambient air quality standards for ozone. | EPA | [62 FR 38894, July 18, 1997, as amended at 77 FR 30170, May 21, 2012; 80 FR 12312, Mar. 6, 2015] | (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. | |||||
| 40:40:2.0.1.1.1.0.1.11 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.11 National primary and secondary ambient air quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). | EPA | [75 FR 6531, Feb. 9, 2010] | (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. | |||||
| 40:40:2.0.1.1.1.0.1.12 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.12 National primary and secondary ambient air quality standards for lead. | EPA | [43 FR 46258, Oct. 5, 1978, as amended at 73 FR 67051, Nov. 12, 2008] | (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. | |||||
| 40:40:2.0.1.1.1.0.1.13 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.13 National primary and secondary ambient air quality standards for PM | EPA | [71 FR 61224, Oct. 17, 2006, as amended at 81 FR 58149, Aug. 24, 2016] | (a) The national primary and secondary ambient air quality standards for particulate matter are 15.0 micrograms per cubic meter (µg/m 3 ) annual arithmetic mean concentration, and 35 µg/m 3 24-hour average concentration measured in the ambient air as PM 2.5 (particles with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers) by either: (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 2.5 standards are met when the annual arithmetic mean concentration, as determined in accordance with appendix N of this part, is less than or equal to 15.0 µg/m 3 . (c) The 24-hour primary and secondary PM 2.5 standards are met when the 98th percentile 24-hour concentration, as determined in accordance with appendix N of this part, is less than or equal to 35 µg/m 3 . (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 2.5 NAAQS set forth in this section will continue in effect, notwithstanding the promulgation of the 2012 primary annual PM 2.5 NAAQS under § 50.18. The 1997 primary annual PM 2.5 NAAQS set forth in this section will no longer apply upon the effective date of the final Fine Particulate Matter National Ambient Air Quality Standards: State Implementation Plan Requirements rule; except that for areas designated nonattainment for the 1997 annual PM 2.5 NAAQS set forth in this section as of the effective date of the final Fine Particulate Matter National Ambient Air Quality Standards: State Implementation Plan Requirements rule, the requirements applicable to the 1997 primary annual PM 2.5 NAAQS set forth in this section will apply until the effective date of an area's redesignation to attainment for the 1997 annual PM 2.5 NAAQS pursua… | |||||
| 40:40:2.0.1.1.1.0.1.14 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.14 Treatment of air quality monitoring data influenced by exceptional events. | EPA | [81 FR 68277, Oct. 3, 2016] | (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 reque… | |||||
| 40:40:2.0.1.1.1.0.1.15 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.15 National primary and secondary ambient air quality standards for ozone. | EPA | [73 FR 16511, Mar. 27, 2008] | (a) The level of the national 8-hour primary and secondary ambient air quality standards for ozone (O 3 ) is 0.075 parts per million (ppm), daily maximum 8-hour average, measured by a reference method based on appendix D to this part and designated in accordance with part 53 of this chapter or an equivalent method designated in accordance with part 53 of this chapter. (b) The 8-hour primary and secondary O 3 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 O 3 concentration is less than or equal to 0.075 ppm, as determined in accordance with appendix P to this part. | |||||
| 40:40:2.0.1.1.1.0.1.16 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.16 National primary and secondary ambient air quality standards for lead. | EPA | [73 FR 67052, Nov. 12, 2008] | (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. | |||||
| 40:40:2.0.1.1.1.0.1.17 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.17 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). | EPA | [75 FR 35592, June 22, 2010] | (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 2 ). (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. | |||||
| 40:40:2.0.1.1.1.0.1.18 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.18 National primary ambient air quality standards for PM | EPA | [78 FR 3277, Jan. 15, 2013] | (a) The national primary ambient air quality standards for PM 2.5 are 12.0 micrograms per cubic meter (µg/m 3 ) annual arithmetic mean concentration and 35 µg/m 3 24-hour average concentration measured in the ambient air as PM 2.5 (particles with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers) by either: (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 2.5 standard is met when the annual arithmetic mean concentration, as determined in accordance with appendix N of this part, is less than or equal to 12.0 µg/m 3 . (c) The primary 24-hour PM 2.5 standard is met when the 98th percentile 24-hour concentration, as determined in accordance with appendix N of this part, is less than or equal to 35 µg/m 3 . | |||||
| 40:40:2.0.1.1.1.0.1.19 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.19 National primary and secondary ambient air quality standards for ozone. | EPA | [80 FR 65452, Oct. 26, 2015] | (a) The level of the national 8-hour primary ambient air quality standard for ozone (O 3 ) is 0.070 parts per million (ppm), daily maximum 8-hour average, measured by a reference method based on appendix D to this part and designated in accordance with part 53 of this chapter or an equivalent method designated in accordance with part 53 of this chapter. (b) The 8-hour primary O 3 ambient air quality standard is met at an ambient air quality monitoring site when the 3-year average of the annual fourth-highest daily maximum 8-hour average O 3 concentration is less than or equal to 0.070 ppm, as determined in accordance with appendix U to this part. (c) The level of the national secondary ambient air quality standard for O 3 is 0.070 ppm, daily maximum 8-hour average, measured by a reference method based on appendix D to this part and designated in accordance with part 53 of this chapter or an equivalent method designated in accordance with part 53 of this chapter. (d) The 8-hour secondary O 3 ambient air quality standard is met at an ambient air quality monitoring site when the 3-year average of the annual fourth-highest daily maximum 8-hour average O 3 concentration is less than or equal to 0.070 ppm, as determined in accordance with appendix U to this part. | |||||
| 40:40:2.0.1.1.1.0.1.2 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.2 Scope. | EPA | [36 FR 22384, Nov. 25, 1971, as amended at 63 FR 7274, Feb. 12, 1998] | (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. | |||||
| 40:40:2.0.1.1.1.0.1.20 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.20 National primary ambient air quality standards for PM | EPA | [89 FR 16380, Mar. 6, 2024] | (a) The national primary ambient air quality standards for PM 2.5 are 9.0 micrograms per cubic meter (µg/m 3 ) annual arithmetic mean concentration and 35 µg/m 3 24-hour average concentration measured in the ambient air as PM 2.5 (particles with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers) by either: (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 2.5 standard is met when the annual arithmetic mean concentration, as determined in accordance with appendix N to this part, is less than or equal to 9.0 µg/m 3 . (c) The primary 24-hour PM 2.5 standard is met when the 98th percentile 24-hour concentration, as determined in accordance with appendix N to this part, is less than or equal to 35 µg/m 3 . | |||||
| 40:40:2.0.1.1.1.0.1.21 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.21 National secondary ambient air quality standards for sulfur oxides (sulfur dioxide). | EPA | [89 FR 105785, Dec. 27, 2024] | (a) The level of the annual secondary national ambient air quality standard for oxides of sulfur is 10 parts per billion (ppb), measured in the ambient air as sulfur dioxide (SO 2 ) by a reference method based on appendix A-1 and appendix A-2 of this part, or by a Federal Equivalent Method (FEM) designated in accordance with part 53 of this chapter. (b) The annual secondary standard is met when the 3-year average of the annual SO 2 concentration is less than or equal to 10 ppb, as determined in accordance with appendix T of this part. | |||||
| 40:40:2.0.1.1.1.0.1.3 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.3 Reference conditions. | EPA | [89 FR 10365, Dec. 19, 2024] | 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 2.5 ) standards contained in §§ 50.7, 50.13, 50.18, and 50.20, and lead standards contained in § 50.16 shall be corrected to a reference temperature of 25 (deg) C and a reference pressure of 760 millimeters of mercury (1,013.2 millibars). Measurements of PM 2.5 for purposes of comparison to the standards contained in §§ 50.7, 50.13, 50.18, and 50.20, and of lead for purposes of comparison to the standards contained in § 50.16 shall be reported based on actual ambient air volume measured at the actual ambient temperature and pressure at the monitoring site during the measurement period. | |||||
| 40:40:2.0.1.1.1.0.1.4 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.4 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). | EPA | [61 FR 25579, May 22, 1996, as amended at 75 FR 35592, June 22, 2010] | (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 2 national ambient air quality standards (NAAQS) in § 50.17. The SO 2 NAAQS set forth in this section will no longer apply to an area one year after the effec… | |||||
| 40:40:2.0.1.1.1.0.1.5 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.5 National secondary ambient air quality standard for sulfur oxides (sulfur dioxide). | EPA | [61 FR 25580, May 22, 1996] | (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. | |||||
| 40:40:2.0.1.1.1.0.1.6 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.6 National primary and secondary ambient air quality standards for PM | EPA | [52 FR 24663, July 1, 1987, as amended at 62 FR 38711, July 18, 1997; 65 FR 80779, Dec. 22, 2000; 71 FR 61224, Oct. 17, 2006] | (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 3 ), 24-hour average concentration. The standards are attained when the expected number of days per calendar year with a 24-hour average concentration above 150 µg/m 3 , as determined in accordance with appendix K to this part, is equal to or less than one. (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 10 (particles with an aerodynamic diameter less than or equal to a nominal 10 micrometers) by: (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. | |||||
| 40:40:2.0.1.1.1.0.1.7 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.7 National primary and secondary ambient air quality standards for PM | EPA | [62 FR 38711, July 18, 1997, as amended at 69 FR 45595, July 30, 2004] | (a) The national primary and secondary ambient air quality standards for particulate matter are 15.0 micrograms per cubic meter (µg/m 3 ) annual arithmetic mean concentration, and 65 µg/m 3 24-hour average concentration measured in the ambient air as PM 2.5 (particles with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers) by either: (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 2.5 standards are met when the annual arithmetic mean concentration, as determined in accordance with appendix N of this part, is less than or equal to 15.0 micrograms per cubic meter. (c) The 24-hour primary and secondary PM 2.5 standards are met when the 98 th percentile 24-hour concentration, as determined in accordance with appendix N of this part, is less than or equal to 65 micrograms per cubic meter. | |||||
| 40:40:2.0.1.1.1.0.1.8 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.8 National primary ambient air quality standards for carbon monoxide. | EPA | [50 FR 37501, Sept. 13, 1985] | (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. | |||||
| 40:40:2.0.1.1.1.0.1.9 | 40 | Protection of Environment | I | C | 50 | PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS | § 50.9 National 1-hour primary and secondary ambient air quality standards for ozone. | EPA | [62 FR 38894, July 18, 1997, as amended at 65 FR 45200, July 20, 2000; 68 FR 38163, June 26, 2003, 69 FR 23996, Apr. 30, 2004; 77 FR 28441, May 14, 2012] | (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 3 ). The standard is attained when the expected number of days per calendar year with maximum hourly average concentrations above 0.12 parts per million (235 µg/m 3 ) is equal to or less than 1, as determined by appendix H to this part. (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. |
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CREATE TABLE cfr_sections (
section_id TEXT PRIMARY KEY,
title_number INTEGER,
title_name TEXT,
chapter TEXT,
subchapter TEXT,
part_number TEXT,
part_name TEXT,
subpart TEXT,
subpart_name TEXT,
section_number TEXT,
section_heading TEXT,
agency TEXT,
authority TEXT,
source_citation TEXT,
amendment_citations TEXT,
full_text TEXT
);
CREATE INDEX idx_cfr_title ON cfr_sections(title_number);
CREATE INDEX idx_cfr_part ON cfr_sections(part_number);
CREATE INDEX idx_cfr_agency ON cfr_sections(agency);