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Interstate Air Pollution Transport

Interstate air pollution transport occurs when air pollution that is generated in one state crosses state borders, affecting air quality in another state.  The Clean Air Act's "good neighbor" provision requires EPA and states to address interstate transport of air pollution that affects downwind states' ability to attain and maintain National Ambient Air Quality Standards (NAAQS).

Basic Information

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  • What is Interstate Air Pollution Transport?
  • What Does the Clean Air Act Say?
  • Interconnected Nature of Regional Pollution Transport

EPA Actions

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  • Rulemakings
    • Good Neighbor Plan for 2015 Ozone NAAQS
    • Revised CSAPR Update
    • CSAPR Update (2017 - Present)
    • CSAPR (2015 - Present)
    • Final Update to NOX SIP Call Regulations (2019-Present)
    • Historical Regulations
  • Other Actions
    • Ozone Transport Commission (OTC) Section 184(c) Petition
    • Memos and Notices

Related Programs

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  • Transboundary Air Pollution Agreements
  • Acid Rain Program
  • Regional Haze Program

Related Tools and Data

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  • Clean Air Status and Trends Network (CASTNET)
  • Air Quality Monitoring
  • Emissions Inventories
  • Power Sector Modeling

What's New

March 15, 2023 – EPA has finalized the Good Neighbor Plan for the 2015 Ozone National Ambient Air Quality Standards (NAAQS).

January 31, 2023 – EPA disapproves Good Neighbor SIP Submissions for the 2015 Ozone NAAQS.

Contact Us to ask a question, provide feedback, or report a problem.
Last updated on May 30, 2023
United States Environmental Protection Agency

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