Cross-State Air Pollution Rule (CSAPR) - Regulatory Actions and Litigation

On this page:

• Rule Summary
• Rule History
• Additional Resources

Rule Summary

On July 6, 2011, the US Environmental Protection Agency (EPA) finalized the Cross-State Air Pollution Rule (CSAPR), limiting the interstate transport of emissions of nitrogen oxides (NO_X) and sulfur dioxide (SO₂) that contribute to harmful levels of fine particle matter (PM_2.5) and ozone in downwind states. The CSAPR requires 28 states in the eastern United States to reduce SO₂, annual NO_X and ozone season NO_X emissions from fossil fuel-fired power plants that affect the ability of downwind states to attain and maintain compliance with the 1997 and 2006 fine particle national ambient air quality standards (NAAQS) and the 1997 ozone NAAQS.

The CSAPR achieves these reductions through emissions trading programs, with Phase 1 beginning in January 2015 for the annual programs and May 2015 for the ozone season program. Phase 2 begins in January 2017 for the annual programs and May 2017 for the ozone season program. The CSAPR will reduce air quality impacts of fine particle and ozone pollution that crosses state lines and will help downwind areas meet and maintain air quality standards. For more information about the CSAPR and how it works, see the CSAPR Basic Information page.

On September 7, 2016, the EPA revised the CSAPR ozone season NO_X emission program by finalizing the CSAPR Update for the 2008 ozone NAAQS. 

Rule History

• Date Change Affirmation Rules
• Revisions Rules
• Supplemental Rules
• Final and Proposed Rules
• Additional Actions

Additional Resources

• Overview of CSAPR
• State Budgets, Variability Limits, and Assurance Provisions
• States Affected by CSAPR
• Compliance and Results

Read the rulemakings and the supporting documentation in the official Docket.