International Transport of Air Pollution
Final Guidance on the Preparation of Clean Air Act Section 179B Demonstrations for Nonattainment Areas Affected by International Transport of Emissions
This guidance will assist state, local, and tribal air agencies that are considering the development of a demonstration, under section 179B of the Clean Air Act (CAA), that a nonattainment area would be able to attain, or would have attained, the relevant National Ambient Air Quality Standard (NAAQS) but for emissions emanating from outside the U.S. To help air agencies better understand how to satisfy the requirements of section 179B, the guidance describes and provides examples of the kinds of information and analyses that EPA recommends air agencies consider including in a section 179B demonstration. EPA accepted comment on the draft guidance from January 9, 2020 through March 10, 2020, and finalized the guidance on December 18, 2020.
Final Guidance on the Preparation of Clean Air Act Section 179B Demonstrations for Nonattainment Areas Affected by International Transport of Emissions (pdf)
January 7, 2021 Federal Register Notice of Final Guidance Availability
Note that EPA's February 12, 2020 webinar (link below) provides a helpful overview of the final section 179B guidance.
Information on the Draft Guidance
- Docket ID No. EPA-HQ-OAR-2019-0668
- Webinar Slides on the Section 179B Demonstration Guidance (pdf)
- Webinar held February 12, 2020
Other Related Resources and Information
- Transboundary Air Pollution
- Treatment of Air Quality Data Influenced by Exceptional Events (Homepage for Exceptional Events)
- Interstate Ozone Air Pollution Transport Homepage
- March 2016 Background Ozone Workshop and Information
- October 2015 Fact Sheet related to addressing background ozone under the 2015 Ozone NAAQS