# 40 CFR § 81.12: National Capital Interstate Air Quality Control Region (District of Columbia, Maryland, and Virginia)

> Federal · Regulations · In force

URL: https://www.frixlaw.com/law-library/statutes/ecfr-40-81.12

## Section

- **Citation:** 40 CFR § 81.12
- **Heading:** National Capital Interstate Air Quality Control Region (District of Columbia, Maryland, and Virginia)
- **Jurisdiction:** Federal
- **Kind:** Regulations
- **Status:** In force
- **Text as of:** September 22, 2026
- **Source:** Publisher's official text
- **Location:** Title 40—Protection of Environment > CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY > SUBCHAPTER C—AIR PROGRAMS > PART 81—DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES > Subpart B—Designation of Air Quality Control Regions

## Text

The National Capital Interstate Air Quality Control Region (District of Columbia, Maryland, and Virginia) consists of the territorial area encompassed by the boundaries of the following jurisdictions (including the territorial area of all municipalities (as defined in section 302(f) of the Clean Air Act, 42 U.S.C. 1857h(f)) geographically located within the outermost boundaries of the area so delimited);
District of Columbia
In the State of Maryland: Montgomery County; Prince Georges County.
In the State of Virginia: Arlington County; Fairfax County; Loudoun County; Prince William County.
(As so delimited, the Virginia portion of the region will include the city of Alexandria, the city of Fairfax, and the city of Falls Church.)

## Nearby sections

- [40 CFR § 81.1 § 81.1 Definitions.](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.1.md)
- [40 CFR § 81.11 § 81.11 Scope.](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.11.md)
- [40 CFR § 81.12 § 81.12 National Capital Interstate Air Quality Control Region (District of Columbia, Maryland, and Virginia).](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.12.md)
- [40 CFR § 81.13 § 81.13 New Jersey-New York-Connecticut Interstate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.13.md)
- [40 CFR § 81.14 § 81.14 Metropolitan Chicago Interstate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.14.md)
- [40 CFR § 81.15 § 81.15 Metropolitan Philadelphia Interstate Air Quality Control Region (Pennsylvania-New Jersey-Delaware).](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.15.md)
- [40 CFR § 81.16 § 81.16 Metropolitan Denver Intrastate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.16.md)
- [40 CFR § 81.17 § 81.17 Metropolitan Los Angeles Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.17.md)
- [40 CFR § 81.18 § 81.18 Metropolitan St. Louis Interstate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.18.md)
- [40 CFR § 81.19 § 81.19 Metropolitan Boston Intrastate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.19.md)
- [40 CFR § 81.20 § 81.20 Metropolitan Cincinnati Interstate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.20.md)
- [40 CFR § 81.21 § 81.21 San Francisco Bay Area Intrastate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.21.md)
- [40 CFR § 81.22 § 81.22 Greater Metropolitan Cleveland Intrastate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.22.md)
- [40 CFR § 81.23 § 81.23 Southwest Pennsylvania Intrastate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/ecfr-40-81.23.md)

---

Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/ecfr-40-81.12. Check the current official text before relying on it. Not legal advice.