---
kind: "section"
citation: "42 U.S.C. § 7492"
title: "42"
title_heading: "The Public Health and Welfare"
number: "7492"
heading: "Visibility"
release: "119-102"
date: "2026-07-12"
url: "https://uscodex.org/usc/42/7492"
units:
  - "Chapter 85 — Air Pollution Prevention and Control"
  - "Subchapter I — Programs and Activities"
  - "Part C — Prevention of Significant Deterioration of Air Quality"
  - "Subpart ii — visibility protection"
---

# §7492. Visibility

- (a) **Studies—**
  - (1) The [Administrator](/usc/42/7602.md?p=a), in conjunction with the National Park Service and other appropriate Federal [agencies](/usc/42/8262.md?p=1), shall conduct research to identify and evaluate sources and source regions of both visibility impairment and regions that provide predominantly clean air in class I areas. A total of $8,000,000 per year for 5 years is authorized to be appropriated for the Environmental Protection [Agency](/usc/42/8262.md?p=1) and the other Federal [agencies](/usc/42/8262.md?p=1) to conduct this research. The research shall include—
    - (A) expansion of current visibility related monitoring in class I areas;
    - (B) assessment of current sources of visibility impairing pollution and clean air corridors;
    - (C) adaptation of regional air quality models for the assessment of visibility;
    - (D) studies of atmospheric chemistry and physics of visibility.
  - (2) Based on the findings available from the research required in [subsection (a)(1)](#a-1) as well as other available scientific and technical data, studies, and other available information pertaining to visibility source-receptor relationships, the [Administrator](/usc/42/7602.md?p=a) shall conduct an assessment and evaluation that identifies, to the extent possible, sources and source regions of visibility impairment including natural sources as well as source regions of clear air for class I areas. The [Administrator](/usc/42/7602.md?p=a) shall produce interim findings from this study within 3 years after November 15, 1990.
- (b) **Impacts of other provisions—** Within 24 months after November 15, 1990, the [Administrator](/usc/42/7602.md?p=a) shall conduct an assessment of the progress and improvements in visibility in class I areas that are likely to result from the implementation of the provisions of the Clean Air Act Amendments of 1990 other than the provisions of this section. Every 5 years thereafter the [Administrator](/usc/42/7602.md?p=a) shall conduct an assessment of actual progress and improvement in visibility in class I areas. The [Administrator](/usc/42/7602.md?p=a) shall prepare a written report on each assessment and transmit copies of these reports to the appropriate committees of Congress.
- (c) **Establishment of visibility transport regions and commissions—**
  - (1) **Authority to establish visibility transport regions—** Whenever, upon the [Administrator](/usc/42/7602.md?p=a)’s motion or by petition from the Governors of at least two affected [States](/usc/42/7602.md?p=d), the [Administrator](/usc/42/7602.md?p=a) has reason to believe that the current or projected interstate transport of [air pollutants](/usc/42/7602.md?p=g) from one or more [States](/usc/42/7602.md?p=d) contributes significantly to visibility impairment in class I areas located in the affected [States](/usc/42/7602.md?p=d), the [Administrator](/usc/42/7602.md?p=a) may establish a transport region for such pollutants that includes such [States](/usc/42/7602.md?p=d). The [Administrator](/usc/42/7602.md?p=a), upon the [Administrator](/usc/42/7602.md?p=a)’s own motion or upon petition from the Governor of any affected [State](/usc/42/7602.md?p=d), or upon the recommendations of a transport commission established under [subsection (b)](#b) of this section[^1] may—
    - (A) add any [State](/usc/42/7602.md?p=d) or portion of a [State](/usc/42/7602.md?p=d) to a visibility transport region when the [Administrator](/usc/42/7602.md?p=a) determines that the interstate transport of [air pollutants](/usc/42/7602.md?p=g) from such [State](/usc/42/7602.md?p=d) significantly contributes to visibility impairment in a class I area located within the transport region, or
    - (B) remove any [State](/usc/42/7602.md?p=d) or portion of a [State](/usc/42/7602.md?p=d) from the region whenever the [Administrator](/usc/42/7602.md?p=a) has reason to believe that the control of emissions in that [State](/usc/42/7602.md?p=d) or portion of the [State](/usc/42/7602.md?p=d) pursuant to this section will not significantly contribute to the protection or enhancement of visibility in any class I area in the region.
  - (2) **Visibility transport commissions—** Whenever the [Administrator](/usc/42/7602.md?p=a) establishes a transport region under [subsection (c)(1)](#c-1), the [Administrator](/usc/42/7602.md?p=a) shall establish a transport commission comprised of (as a minimum) each of the following members:
    - (A) the Governor of each [State](/usc/42/7602.md?p=d) in the Visibility Transport Region, or the Governor’s designee;
    - (B) The[^2] [Administrator](/usc/42/7602.md?p=a) or the [Administrator](/usc/42/7602.md?p=a)’s designee; and
    - (C) A[^2] representative of each Federal [agency](/usc/42/8262.md?p=1) charged with the direct management of each class I area or areas within the Visibility Transport Region.
  - (3) **Ex officio members—** All representatives of the Federal Government shall be ex officio members.
  - (4) **Chapter 10 of title 5—** The visibility transport commissions shall be exempt from the requirements of chapter 10 of title 5.
- (d) **Duties of visibility transport commissions—** A Visibility Transport Commission—
  - (1) shall assess the scientific and technical data, studies, and other currently available information, including studies conducted pursuant to [subsection (a)(1)](#a-1), pertaining to adverse impacts on visibility from potential or projected growth in emissions from sources located in the Visibility Transport Region; and
  - (2) shall, within 4 years of establishment, issue a report to the [Administrator](/usc/42/7602.md?p=a) recommending what measures, if any, should be taken under this chapter to remedy such adverse impacts. The report required by this subsection shall address at least the following measures:
    - (A) the establishment of clean air corridors, in which additional restrictions on increases in emissions may be appropriate to protect visibility in affected class I areas;
    - (B) the imposition of the requirements of part D of this subchapter affecting the [construction](/usc/42/7479.md?p=2-C) of new [major stationary sources](/usc/42/7602.md?p=j) or major [modifications](/usc/42/7501.md?p=4) to existing sources in such clean air corridors specifically including the alternative siting analysis provisions of [section 7503(a)(5) of this title](/usc/42/7503.md?p=a-5); and
    - (C) the promulgation of regulations under [section 7491 of this title](/usc/42/7491.md) to address long range strategies for addressing regional haze which impairs visibility in affected class I areas.
- (e) **Duties of Administrator—**
  - (1) The [Administrator](/usc/42/7602.md?p=a) shall, taking into account the studies pursuant to [subsection (a)(1)](#a-1) and the reports pursuant to [subsection (d)(2)](#d-2) and any other relevant information, within eighteen months of receipt of the report referred to in [subsection (d)(2)](#d-2) of this section, carry out the [Administrator](/usc/42/7602.md?p=a)’s regulatory responsibilities under [section 7491 of this title](/usc/42/7491.md), including criteria for measuring “reasonable progress” toward the national goal.
  - (2) Any regulations promulgated under [section 7491 of this title](/usc/42/7491.md) pursuant to this subsection shall require affected [States](/usc/42/7602.md?p=d) to revise within 12 months their implementation plans under [section 7410 of this title](/usc/42/7410.md) to contain such emission limits, schedules of compliance, and other measures as may be necessary to carry out regulations promulgated pursuant to this subsection.
- (f) **Grand Canyon visibility transport commission—** The [Administrator](/usc/42/7602.md?p=a) pursuant to [subsection (c)(1)](#c-1) shall, within 12 months, establish a visibility transport commission for the region affecting the visibility of the Grand Canyon National Park.

## Footnotes

[^1]: So in original. Words “subsection (b) of this section” probably should be “paragraph (2)”.
[^2]: So in original. Probably should not be capitalized.

## Source credit

(July 14, 1955, ch. 360, title I, § 169B, as added Pub. L. 101–549, title VIII, § 816, Nov. 15, 1990, 104 Stat. 2695; amended Pub. L. 117–286, § 4(a)(269), Dec. 27, 2022, 136 Stat. 4335.)

## Notes

### Editorial Notes

### References in Text

The Clean Air Act Amendments of 1990, referred to in subsec. (b), probably means Pub. L. 101–549, Nov. 15, 1990, 104 Stat. 2399. For complete classification of this Act to the Code, see Short Title note set out under section 7401 of this title and Tables.

### Amendments

2022—Subsec. (c)(4). Pub. L. 117–286 substituted “chapter 10 of title 5.” for “the Federal Advisory Committee Act.”