Beveridge & Diamond
Related Practices
Related Practices

EPA Finalizes Greenhouse Gas Endangerment Finding

Beveridge & Diamond, P.C., December 8, 2009

On December 7, 2009, Environmental Protection Agency (“EPA”) Administrator Lisa Jackson signed the Agency’s final “endangerment” and “cause or contribute” findings for greenhouse gases (“GHGs”).  First proposed by EPA on April 24, 2009, the findings respond to the U.S. Supreme Court’s 2007 decision in Massachusetts v. EPA, 549 U.S. 497 (2007).  See EPA Issues Proposed Endangerment Finding for GHGs,  In that case, the Court held that GHGs are air pollutants under the Clean Air Act, and that EPA therefore must determine whether GHG emissions from new motor vehicles “cause or contribute to” air pollution that may reasonably be anticipated to “endanger” public health or welfare. 

Collectively referred to as the “Endangerment Finding,” the final action by EPA actually consists of two distinct findings regarding GHGs:

  • Endangerment Finding:  EPA has concluded that current and projected concentrations of six key GHGs in the atmosphere – carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) – “endanger both the public health and the public welfare of current and future generations.”  EPA defines the group of these six “well-mixed greenhouse gases” collectively as an “air pollutant” under the Clean Air Act.
  • Cause or Contribute Finding:  EPA also concluded that the combined emissions of the “well-mixed greenhouse gases” from new motor vehicles and new motor vehicle engines contribute to pollution that threatens the public health and welfare.  Though these transportation sources emit only four of the key GHGs (CO2, CH4, N2O, and HFCs), EPA defined the contributing “air pollutant” as the aggregate of the “well-mixed greenhouse gases.”  EPA’s contribute finding paves the way for regulating emissions from vehicles.

The Endangerment Finding alone does not directly impose any requirements on GHG sources.  The issuance of the Finding, however, now authorizes – and obligates – EPA to regulate GHGs from motor vehicles and engines pursuant to section 202(a)(1) of the Clean Air Act.  The Endangerment Finding provides the legal basis for EPA to finalize its proposed “Light Duty Vehicle Rule.”  See 74 Fed. Reg. 49,454 (Sept. 28, 2009).  This rule, proposed in conjunction with National Highway Traffic Safety Administration (“NHTSA”) Corporate Average Fuel Economy standards and applicable to various passenger vehicles and light-duty trucks, would establish regulations aimed at reducing GHG emissions from these vehicles, as well as improving their fuel economy.  EPA proposed the Light Duty Vehicle Rule on September 28, 2009, and intends to finalize the Rule in March, 2010.  According to EPA, once finalized, the Light Duty Vehicle Rule will make GHGs a “regulated pollutant” under the Clean Air Act, thereby triggering requirements of the statute’s construction and operating permit programs for stationary sources, in addition to the regulatory requirements that will apply to mobile sources.

In finalizing the Endangerment Finding, EPA reviewed and considered more than 380,000 comments.  The Agency has prepared responses to these comments in eleven volumes, with each volume focusing on a different broad category of comments.

At this time, EPA has released a pre-publication copy of the Endangerment Finding as well as the accompanying technical support materials and responses to comments on its website at:  The final Endangerment Finding will be published in the Federal Register in the coming days.

For more information about EPA’s Endangerment Finding and its relation to other EPA rules regarding GHGs, please contact David Friedland, at or (202) 789-6047, or Tom Richichi, at or (202) 789-6026.  This alert was prepared with the assistance of Sean Roberts. 




Media Contact

Attorney Contacts
Attorney Contacts