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EPA Issues Proposed Endangerment Finding for GHGs

Beveridge & Diamond, P.C., April 24, 2009

The U.S. Environmental Protection Agency (“EPA”) published in the Federal Register today its proposed Endangerment Finding for greenhouse gases (“GHGs”).  Although the proposed findings are keyed to section 202(a) of the Clean Air Act, which addresses emissions from motor vehicles, the proposal lays the initial groundwork for potentially widespread climate change-related regulatory initiatives under EPA’s existing Clean Air Act authorities. 

At the same time, the proposal suggests that EPA intends to follow a careful -- and potentially lengthy -- process for developing regulatory standards under these authorities, particularly with respect to the extension of such authority to source categories beyond motor vehicles.  The proposal also makes it clear that EPA intends to reserve significant discretion to itself both for prioritizing additional source categories and for crafting regulatory standards.  As such, it appears that the Administration intends to use the Endangerment Finding and its regulatory progeny as flexible tools for mitigating climate change emissions in the United States, while at the same time serving as an adjustable source of leverage to influence the Congress’ consideration of dedicated new climate change legislation.

Proposed Findings

The proposal contains two major elements:

  1. A broad “Endangerment Finding”:  EPA proposes to find that the mix of six key greenhouse gases (CO2, CH4, N2O, HFCs, PFCs, and SF6) in the atmosphere “may reasonably be anticipated to endanger public health and welfare.”

 Although EPA is careful to position its proposal under section 202(a) of the Clean Air Act, its conclusions about the risks of these gases and their impacts are broadly formulated to serve as a platform for regulatory action for other source categories regulated under the Act.  EPA gives considerable attention to its assertion that the statute gives the Administrator broad discretion to adopt a precautionary approach in the face of uncertainties and imperfect information, based on her judgment and future projections. 

  1. A targeted “Cause or Contribute Finding”:  EPA proposes to find that the combined emissions of a subset of these GHGs (CO2, CH4, N2O, and HFCs) from new motor vehicles and new motor vehicle engines contribute to the air pollution that is endangering the public health and welfare, thus triggering EPA’s regulatory authority to address those sources. 

EPA asserts that the statutory threshold in section 202(a) leaves considerable discretion to the Agency to determine the point at which a source category “contributes to” the “dangerous” air pollution.  There is no bright line that triggers the cause or contribute finding or its implications.  Indeed, EPA asserts that it:

"may determine that emissions at a certain level or percentage contribute to air pollution in one set of circumstances, while also judging that the same level or percentage of another air pollutant in different circumstances and involving different air pollution does not contribute.  When exercising her judgment, the Administrator not only considers the cumulative impact, but also looks at the totality of the circumstances (e.g., the air pollutant, the air pollution, the nature of the endangerment, the type of source category, the number of sources in the source category, and the number and type of other source categories that may emit the air pollutant) when determining whether the emissions ‘justify regulation’ under the CAA."

Although linked in this case to the “cause or contribute” finding for motor vehicle emissions, the general approach EPA adopts here will likely prove useful to the agency as it applies its Endangerment Finding to other source categories addressed under the Clean Air Act as well.

Next Steps

EPA did not issue proposed standards to address emissions from motor vehicles under Section 202(a) today.  Instead it chose to issue its proposed findings under a notice and comment procedure, and to conduct separate notice and comment procedures for the adoption of regulatory standards for motor vehicles in the future.  EPA left itself flexibility regarding next steps, indicating that it expects to release a proposed rule on regulatory standards in “several months.”  These choices, which entail additional procedures that will unfold at a pace largely to be set by EPA, provide the first indication that the Administration intends to move deliberately and over time to impose GHG regulations under the CAA.

EPA released a pre-publication version of the proposed finding on April 17, 2009. Today’s publication in the Federal Register opens the proposal for public comment. Comments are due on or before June 23, 2009.  Public hearings are scheduled for May 18, 2009 in Arlington, Virginia, and May 21, 2009 in Seattle, Washington.  After reviewing the comments, EPA will finalize its findings.   

Additional Resources

Background documents relating to the finding are available through the EPA website at:

For more information, please contact David Friedland (, Russ LaMotte ( or Tom Richichi (




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