---
kind: "section"
citation: "40 C.F.R. § 51.1108"
title: "40"
number: "51.1108"
heading: "Modeling and attainment demonstration requirements."
url: "https://uscodex.org/cfr/40/51.1108"
---

# §51.1108. Modeling and attainment demonstration requirements.

- (a) An area classified as Moderate under [§ 51.1103(a)](/cfr/40/51.1103.md?p=a) shall be subject to the attainment demonstration requirement applicable for that classification under CAA [section 182(b)](/cfr/40/182.md?p=b), and such demonstration is due no later than 36 months after the effective date of the area's designation for the 2008 ozone NAAQS.
- (b) An area classified as Serious or higher under [§ 51.1103(a)](/cfr/40/51.1103.md?p=a) shall be subject to the attainment demonstration requirement applicable for that classification under CAA [section 182(c)](/cfr/40/182.md?p=c), and such demonstration is due no later than 48 months after the effective date of the area's designation for the 2008 ozone NAAQS.
- (c) **Attainment demonstration criteria.** An attainment demonstration due pursuant to paragraph [(a)](#a) or [(b)](#b) of this section must meet the requirements of [§ 51.112](/cfr/40/51.112.md); the adequacy of an attainment demonstration shall be demonstrated by means of a photochemical grid model or any other analytical method determined by the Administrator, in the Administrator's discretion, to be at least as effective.
- (d) **Implementation of control measures.** For each nonattainment area, the state must provide for implementation of all control measures needed for attainment no later than the beginning of the attainment year ozone season.

## Notes

### Amendments

[80 FR 12314, Mar. 6, 2015]

### Source

Source: 77 FR 30170, May 21, 2012, unless otherwise noted.

### Authority

Authority: 23 U.S.C. 101; 42 U.S.C. 7401-7671q.

### Source

Source: 36 FR 22398, Nov. 25, 1971, unless otherwise noted.

### Amendments

[80 FR 12314, Mar. 6, 2015]