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Title 40

Displaying title 40, up to date as of 7/16/2026. Title 40 was last amended 7/16/2026.
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  1. Title 40 —Protection of Environment
  2. Chapter I —Environmental Protection Agency
  3. Subchapter C —Air Programs
  4. Part 51 —Requirements for Preparation, Adoption, and Submittal of Implementation Plans
  5. Subpart X   View Full Text
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Title 40Protection of EnvironmentPart / Section
Chapter IEnvironmental Protection Agency1 – 1099
Subchapter CAir Programs50 – 99
Part 51Requirements for Preparation, Adoption, and Submittal of Implementation Plans51.1 – 51.1403
Subpart XProvisions for Implementation of 8-hour Ozone National Ambient Air Quality Standard51.900 – 51.919
§ 51.900Definitions.
§ 51.901Applicability of part 51.
§ 51.902Which classification and nonattainment area planning provisions of the CAA shall apply to areas designated nonattainment for the 1997 8-hour NAAQS?
§ 51.903How do the classification and attainment date provisions in section 181 of subpart 2 of the CAA apply to areas subject to § 51.902(a)?
§ 51.904How do the classification and attainment date provisions in section 172(a) of subpart 1 of the CAA apply to areas subject to § 51.902(b)?
§ 51.905How do areas transition from the 1-hour NAAQS to the 1997 8-hour NAAQS and what are the anti-backsliding provisions?
§ 51.906Redesignation to nonattainment following initial designations for the 8-hour NAAQS.
§ 51.907For an area that fails to attain the 8-hour NAAQS by its attainment date, how does EPA interpret sections 172(a)(2)(C)(ii) and 181(a)(5)(B) of the CAA?
§ 51.908What modeling and attainment demonstration requirements apply for purposes of the 8-hour ozone NAAQS?
§ 51.909 [Reserved]
§ 51.910What requirements for reasonable further progress (RFP) under sections 172(c)(2) and 182 apply for areas designated nonattainment for the 8-hour ozone NAAQS?
§ 51.911 [Reserved]
§ 51.912What requirements apply for reasonably available control technology (RACT) and reasonably available control measures (RACM) under the 8-hour NAAQS?
§ 51.913How do the section 182(f) NOX exemption provisions apply for the 8-hour NAAQS?
§ 51.914What new source review requirements apply for 8-hour ozone nonattainment areas?
§ 51.915What emissions inventory requirements apply under the 8-hour NAAQS?
§ 51.916What are the requirements for an Ozone Transport Region under the 8-hour NAAQS?
§ 51.917What is the effective date of designation for the Las Vegas, NV, 8-hour ozone nonattainment area?
§ 51.918Can any SIP planning requirements be suspended in 8-hour ozone nonattainment areas that have air quality data that meets the NAAQS?
§ 51.919Applicability.
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