On July 6, 2011, EPA finalized the Cross-State Air Pollution Rule (CSAPR) under the Clean Air Act, which requires states take action to mitigate cross-border air pollution.

The CSAPR, also known as the Clean Air Transport Rule, provides a national regulatory framework for reducing sulfur dioxide and nitrogen oxide emissions from more than 1,000 power plants in the eastern United States as they contribute detrimentally to the National Ambient Air Quality Standards for ozone and fine particulate matter in “downwind” states. 

The Rule requires significant reductions in sulfur dioxide and nitrogen oxide emissions that cross state lines. Plants in the 27 impacted states in the CSAPR region will be required to comply with emission reductions quickly: beginning January 1, 2012 for sulfur dioxide and annual nitrogen oxide reductions, and May 1, 2012 for ozone season nitrogen oxide reductions.

The Clean Air Transport Rule replaces EPA’s 2005 Clean Air Interstate Rule (CAIR).  A December 2008 court decision kept the requirements of CAIR in place temporarily but directed EPA to issue a new rule to implement Clean Air Act requirements concerning the transport of air pollution across state boundaries. EPA’s latest rule directly responds to the court’s concerns. More information about the Rule is available on EPA’s website at http://www.epa.gov/airtransport/.

EPA is expected to issue final rules regarding numerous Clean Air Act matters over the next two years, including regulations of greenhouse gases and disposal of coal combustion residuals.  In fact, at the same time that it finalized this Clean Air Transport Rule, EPA also issued a Supplemental Notice of Proposed Rulemaking that would subject an additional six states to seasonal ozone reduction requirements.