§ 51.1100 Definitions.

The following definitions apply for purposes of this subpart. Any term not defined herein shall have the meaning as defined in 40 CFR 51.100.

(a) 1-hour NAAQS means the 1-hour primary and secondary ozone national ambient air quality standards codified at 40 CFR 50.9.

(b) 1997 NAAQS means the 1997 8-hour primary and secondary ozone national ambient air quality standards codified at 40 CFR 50.10.

(c) 2008 NAAQS means the 2008 8-hour primary and secondary ozone NAAQS codified at 40 CFR 50.15.

(d) 1-hour ozone design value is the 1-hour ozone concentration calculated according to 40 CFR part 50, appendix H and the interpretation methodology issued by the Administrator most recently before the date of the enactment of the CAA Amendments of 1990.

(e) 8-hour ozone design value is the 8-hour ozone concentration calculated according to 40 CFR part 50, appendix P.

(f) CAA means the Clean Air Act as codified at 42 U.S.C. 7401—7671q (2010).

(g) Attainment area means, unless otherwise indicated, an area designated as either attainment, unclassifiable, or attainment/unclassifiable.

(h) Attainment year ozone season shall mean the ozone season immediately preceding a nonattainment area's maximum attainment date.

(i) Designation for the 2008 NAAQS shall mean the effective date of the designation for an area for the 2008 NAAQS.

(j) 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; and Extreme.