On December 7, 2009, the U.S. Environmental Protection Agency (EPA) issued two findings regarding greenhouse gases under the federal Clean Air Act:

  • Endangerment finding: The EPA found that current and projected atmospheric concentrations of the six key greenhouse gases threaten the public health and welfare of current and future generations.
  • Cause or contribution finding: The EPA also found that the combined emissions of these greenhouse gases from new motor vehicles and engines contribute to the greenhouse gas pollution, which threatens public health and welfare.

Although they do not impose any requirements on industry or other entities, these findings enable the EPA to finalize the greenhouse gas emission standards for light-duty vehicles, which it jointly proposed with the Department of Transportation on September 15, 2009.

These findings follow the important 2007 U.S. Supreme Court decision, Massachusetts v. EPA, in which the Court found that greenhouse gases are air pollutants covered by the Clean Air Act. It remains to be seen whether the EPA will build on its recent endangerment finding to regulate greenhouse gas emissions from stationary sources, should Congress prove unwilling or unable to pass comprehensive legislation in this regard.

For further information, please see the EPA’s website.