The Cross-State Air Pollution Rule

The U.S. Environmental Protection Agency (EPA) finalized a rule on July 6, 2011, that protects the health of millions of Americans by helping states reduce air pollution and meet Clean Air Act standards. Replacing the EPA’s 2005 Clean Air Interstate Rule (CAIR), the first phase of compliance of the Cross-State Air Pollution Rule will go into effect January 1, 2012. Twenty-seven states in the eastern half of the U.S. are required to significantly improve air quality by reducing power plant emissions that cross state lines and contribute to ground-level ozone and fine particle pollution in other states. This final rule requires significant reductions in sulfur dioxide (SO2) and nitrogen oxides (NOX) from power plants. These pollutants react in the atmosphere to form PM2.5 and ground-level ozone and are transported long distances, making it difficult for a number of states to meet the national clean air standards that Congress directed EPA to establish to protect public health.

A court decision in December 2008 determined there were flaws in CAIR, but kept CAIR requirements in place temporarily while directing EPA to issue a replacement rule. To address the problem of air pollution that is transported across state boundaries and in response to the court’s instruction to replace CAIR as quickly as possible, the EPA is adopting federal implementation plans (FIPs) for each of the states covered by this rule. States may replace the FIPs with State Implementation Plans (SIPs) to achieve the required reductions.

By 2014, the Cross-State Air Pollution Rule and other final state and EPA actions are projected to reduce power plant SO2 emissions by 73 percent from 2005 levels. Power plant NOX emissions are projected to drop by 54 percent. This rule also lays out a process for determining each upwind state's responsibility to protect downwind air quality. Each time the National Ambient Air Quality Standards (NAAQS) are changed, EPA can apply this process and determine if interstate pollution transport contributes to exceedances of the new standard and whether new emission reductions should be required from upwind states.

To view or download a copy of the final rule, visit www.epa.gov/airtransport.