Code of Federal Regulations > Title 40 > Chapter I > Part 51 > Subpart X - Subpart X—Provisions for Implementation of 8-hour Ozone National Ambient Air Quality Standard

U.S. Code of Federal Regulations

Regulations most recently checked for updates: Feb 11, 2026

§ 51.900 - Definitions.

§ 51.901 - Applicability of part 51.

§ 51.902 - Which classification and nonattainment area planning provisions of the CAA shall apply to areas designated nonattainment for the 1997 8-hour NAAQS?

§ 51.903 - How do the classification and attainment date provisions in section 181 of subpart 2 of the CAA apply to areas subject to § 51.902(a)?

§ 51.904 - How 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)?

§ 51.905 - How do areas transition from the 1-hour NAAQS to the 1997 8-hour NAAQS and what are the anti-backsliding provisions?

§ 51.906 - Redesignation to nonattainment following initial designations for the 8-hour NAAQS.

§ 51.907 - For 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?

§ 51.908 - What modeling and attainment demonstration requirements apply for purposes of the 8-hour ozone NAAQS?

§ 51.909 - [Reserved]

§ 51.910 - What 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]

§ 51.912 - What requirements apply for reasonably available control technology (RACT) and reasonably available control measures (RACM) under the 8-hour NAAQS?

§ 51.913 - How do the section 182(f) NOX exemption provisions apply for the 8-hour NAAQS?

§ 51.914 - What new source review requirements apply for 8-hour ozone nonattainment areas?

§ 51.915 - What emissions inventory requirements apply under the 8-hour NAAQS?

§ 51.916 - What are the requirements for an Ozone Transport Region under the 8-hour NAAQS?

§ 51.917 - What is the effective date of designation for the Las Vegas, NV, 8-hour ozone nonattainment area?

§ 51.918 - Can any SIP planning requirements be suspended in 8-hour ozone nonattainment areas that have air quality data that meets the NAAQS?

§ 51.919 - Applicability.