40 C.F.R. § 51.1103 : Protection of Environment — ENVIRONMENTAL PROTECTION AGENCY — AIR PROGRAMS — REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS — PROVISIONS FOR IMPLEMENTATION OF THE 2008 OZONE NATIONAL AMBIENT AIR QUALITY STANDARDS — Application of classification and attainment date provisions in CAA section 181 to areas subject to Section 51.1102

(a) In accordance with CAA section 181(a)(1), each area designated nonattainment for the 2008 ozone NAAQS shall be classified by operation of law at the time of designation. The classification shall be based on the 8-hour design value for the area at the time of designation, in accordance with Table 1 below. A state may request a higher or lower classification as provided in paragraphs (b) and (c) of this section. For each area classified under this section, the attainment date for the 2008 NAAQS shall be as expeditious as practicable but not later than the date provided in Table 1 as follows:

TABLE 1-CLASSIFICATIONS AND ATTAINMENT DATES FOR 2008 8-HOUR OZONE NAAQS (0.075 PPM) FOR AREAS SUBJECT TO CFR SECTION 51.1102

Area class 8-hour design value (ppm ozone) Primary standard attainment date (years after the
effective date of designation for 2008 primary NAAQS)
Marginal from 0.076 3
up to* 0.086
Moderate from 0.086 6
up to* 0.100
Serious from 0.100 9
up to* 0.113
Severe-15 from 0.113 15
up to* 0.119
Severe-17 from 0.119 17
up to* 0.175
Extreme equal to or above 0.175 20

*But not including

(b) A state may request, and the Administrator must approve, a higher classification for any reason in accordance with CAA section 181(b)(3).
(c) A state may request, and the Administrator may in the Administrator's discretion approve, a higher or lower classification in accordance with CAA section 181(a)(4).
(d) The following nonattainment areas are reclassified for the 2008 ozone NAAQS as follows: Serious-Ventura County, CA; Severe-Los Angeles-San Bernardino Counties (West Mojave Desert), Riverside County (Coachella Valley), and Sacramento Metro, CA; Extreme-Los Angeles-South Coast Air Basin, and San Joaquin Valley, CA.

40 C.F.R. §51.1103

77 FR 30170, 5/21/2012, as amended at 80 FR 12313, 3/6/2015