CFR > Title 40 - Protection of Environment > CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY > SUBCHAPTER C—AIR PROGRAMS (Parts 50–99) > PART 51—REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS > SUBPART X—Provisions for Implementation of 8-hour Ozone National Ambient Air Quality Standard (§51.900 to §51.918) > 51.902—Which classification and nonattainment area planning provisions of the CAA shall apply to areas designated nonattainment for the 8-hour NAAQS?

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

(a) Classification under An area designated nonattainment for the 8-hour NAAQS with a 1-hour ozone design value equal to or greater than 0.121 ppm at the time the Administrator signs a final rule designating or redesignating the area as nonattainment for the 8-hour NAAQS will be classified in accordance with section 181 of the CAA, as interpreted in § 51.903(a), for purposes of the 8-hour NAAQS, and will be subject to the requirements of subpart that apply for that classification.
(b) Covered under An area designated nonattainment for the 8-hour ozone NAAQS with a 1-hour design value less than 0.121 ppm at the time the Administrator signs a final rule designating or redesignating the area as nonattainment for the 8-hour NAAQS will be covered under section 172(a)(1) of the CAA and will be subject to the requirements of subpart .