---
kind: "section"
citation: "42 U.S.C. § 7478"
title: "42"
title_heading: "The Public Health and Welfare"
number: "7478"
heading: "Period before plan approval"
release: "119-102"
url: "https://uscodex.org/usc/42/7478"
units:
  - "Chapter 85 — Air Pollution Prevention and Control"
  - "Subchapter I — Programs and Activities"
  - "Part C — Prevention of Significant Deterioration of Air Quality"
  - "Subpart i — clean air"
---

# §7478. Period before plan approval

- (a) **Existing regulations to remain in effect—** Until such time as an [applicable implementation plan](/usc/42/7602.md?p=q) is in effect for any area, which plan meets the requirements of this part to prevent significant deterioration of air quality with respect to any [air pollutant](/usc/42/7602.md?p=g), applicable regulations under this chapter prior to August 7, 1977, shall remain in effect to prevent significant deterioration of air quality in any such area for any such [pollutant](/usc/42/1397h.md?p=c-4) except as otherwise provided in [subsection (b)](#b).
- (b) **Regulations deemed amended; construction commenced after June 1, 1975—** If any regulation in effect prior to August 7, 1977, to prevent significant deterioration of air quality would be inconsistent with the requirements of [section 7472(a)](/usc/42/7472.md?p=a), [section 7473(b)](/usc/42/7473.md?p=b) or [section 7474(a) of this title](/usc/42/7474.md?p=a), then such regulations shall be deemed amended so as to conform with such requirements. In the case of a [facility](/usc/42/11049.md?p=4) on which [construction](/usc/42/7479.md?p=2-C) was [commenced](/usc/42/7479.md?p=2-A) (in accordance with the definition of “[commenced](/usc/42/7479.md?p=2-A)” in [section 7479(2) of this title](/usc/42/7479.md?p=2)) after June 1, 1975, and prior to August 7, 1977, the review and permitting of such [facility](/usc/42/11049.md?p=4) shall be in accordance with the regulations for the prevention of significant deterioration in effect prior to August 7, 1977.

## Source credit

(July 14, 1955, ch. 360, title I, § 168, as added Pub. L. 95–95, title I, § 127(a), Aug. 7, 1977, 91 Stat. 740; amended Pub. L. 95–190, § 14(a)(52), Nov. 16, 1977, 91 Stat. 1402.)

## Notes

### Editorial Notes

### Amendments

1977—Subsec. (b). Pub. L. 95–190 substituted “(in accordance with the definition of ‘commenced’ in section 7479(2) of this title)” for “in accordance with this definition”.