§ 51.1300 Definitions.

The following definitions apply for purposes of this subpart. Any term not defined herein shall have the meaning as defined in § 51.100.

(a) 2015 NAAQS. The 2015 8-hour primary and secondary ozone NAAQS codified at 40 CFR 50.19.

(b) 8-hour ozone design value. The 8-hour ozone concentration calculated according to 40 CFR part 50, appendix P, for the 2008 NAAQS, and 40 CFR part 50, appendix U, for the 2015 NAAQS.

(c) CAA. The Clean Air Act as codified at 42 U.S.C. 7401–7671q (2010).

(d) Designation for a NAAQS. The effective date of the designation for an area for that NAAQS.

(e) Higher classification/lower classification. For purposes of determining whether a classification is higher or lower, classifications under subpart 2 of part D of title I of the CAA are ranked from lowest to highest as follows: Marginal; Moderate; Serious; Severe-15; Severe-17; and Extreme.