# 40 C.F.R. § 81.18 (2026): Metropolitan St. Louis Interstate Air Quality Control Region

> Federal · Regulations · In force

URL: https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_18

## Section

- **Citation:** 40 C.F.R. § 81.18 (2026)
- **Heading:** Metropolitan St. Louis Interstate Air Quality Control Region
- **Jurisdiction:** Federal
- **Kind:** Regulations
- **Status:** In force
- **Text as of:** August 14, 2026
- **Source:** Compiled text
- **Location:** Title 40 CFR: Protection of Environment / Chapter I / Part 81 / Subpart B / § 81.18: § 81.18   Metropolitan St. Louis Interstate Air Quality Control Region.

## Text

The Metropolitan St. Louis Interstate Air Quality Control Region (Missouri-Illinois) is revised to consist of the territorial area encompassed by the boundaries of the following jurisdictions or described area (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): In the State of Illinois: Bond County, Clinton County, Madison County, Monroe County, Randolph County, St. Clair County, Washington County. In the State of Missouri: Franklin County, Jefferson County, St. Charles County, St. Louis City, St. Louis County.

## Nearby sections

- [40 C.F.R. § 81.11 (2026) § 81.11   Scope.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_11.md)
- [40 C.F.R. § 81.12 (2026) § 81.12   National Capital Interstate Air Quality Control Region (District of Columbia, Maryland, and Virginia).](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_12.md)
- [40 C.F.R. § 81.13 (2026) § 81.13   New Jersey-New York-Connecticut Interstate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_13.md)
- [40 C.F.R. § 81.14 (2026) § 81.14   Metropolitan Chicago Interstate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_14.md)
- [40 C.F.R. § 81.15 (2026) § 81.15   Metropolitan Philadelphia Interstate Air Quality Control Region (Pennsylvania-New Jersey-Delaware).](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_15.md)
- [40 C.F.R. § 81.16 (2026) § 81.16   Metropolitan Denver Intrastate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_16.md)
- [40 C.F.R. § 81.17 (2026) § 81.17   Metropolitan Los Angeles Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_17.md)
- [40 C.F.R. § 81.18 (2026) § 81.18   Metropolitan St. Louis Interstate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_18.md)
- [40 C.F.R. § 81.19 (2026) § 81.19   Metropolitan Boston Intrastate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_19.md)
- [40 C.F.R. § 81.20 (2026) § 81.20   Metropolitan Cincinnati Interstate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_20.md)
- [40 C.F.R. § 81.21 (2026) § 81.21   San Francisco Bay Area Intrastate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_21.md)
- [40 C.F.R. § 81.22 (2026) § 81.22   Greater Metropolitan Cleveland Intrastate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_22.md)
- [40 C.F.R. § 81.23 (2026) § 81.23   Southwest Pennsylvania Intrastate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_23.md)
- [40 C.F.R. § 81.24 (2026) § 81.24   Niagara Frontier Intrastate Air Quality Control Region.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_24.md)

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Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/CFR_T40_P81_S81_18. Check the current official text before relying on it. Not legal advice.