40 CFR § 51.1103 - Application of classification and attainment date provisions in CAA section 181 to areas subject to § 51.1102.

---
identifier: "/us/cfr/t40/s51.1103"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 51.1103 - Application of classification and attainment date provisions in CAA section 181 to areas subject to § 51.1102."
title_number: 40
title_name: "Protection of Environment"
section_number: "51.1103"
section_name: "Application of classification and attainment date provisions in CAA section 181 to areas subject to § 51.1102."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "C"
subchapter_name: "AIR PROGRAMS"
part_number: "51"
part_name: "REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "23 U.S.C. 101; 42 U.S.C. 7401-7671q."
regulatory_source: "36 FR 22398, Nov. 25, 1971, unless otherwise noted."
cfr_part: "51"
---


# 51.1103 Application of classification and attainment date provisions in CAA section 181 to areas subject to § 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 theeffective 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.

[77 FR 30170, May 21, 2012, as amended at 80 FR 12313, Mar. 6, 2015]