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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

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

EPA Actions

  • 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

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

Related Tools and Data

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

What's New

March 11, 2022 – EPA announced “Good Neighbor” Plan to cut smog across much of the United States.

March 15, 2021 – EPA finalized Revised the Cross-State Air Pollution Rule Update for the 2008 ozone National Ambient Air Quality Standards (NAAQS).

February 16, 2021 – EPA issued notice of comment period extension for Ozone Transport Commission (OTC) Section 184(c) recommendation.

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Last updated on March 11, 2022