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EPA Finds That Greenhouse Gases Endanger the Public Health and Welfare

The Environmental Protection Agency announced yesterday that greenhouse gases, including those emitted by motor vehicles, pose a threat to the public health and welfare of the American people. By issuing this new endangerment finding under Section 202(a) of the Clean Air Act, EPA has paved the way for the promulgation of greenhouse gas emissions standards for new motor vehicles as part of a joint rulemaking with the Department of Transportation. EPA's announcement stems from the Supreme Court's decision in Massachusetts v. EPA, 549 U.S. 497 (2007), which found that greenhouse gases could be air pollutants covered by the Clean Air Act, and that EPA's previously stated reasons for declining to regulate such emissions were an abuse of its discretion. Massachusetts v. EPA required the EPA Administrator to determine whether emissions of greenhouse gases from new motor vehicles cause or contribute to air pollution which may reasonably be anticipated to endanger the public health or welfare.

EPA's Action

Administrator Jackson announced two new findings regarding greenhouse gases under Section 202(a) of the Clean Air Act:

  • First, EPA found that the current and projected atmospheric concentrations of six key greenhouse gases—carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride—threaten the public health and welfare of current and future generations.
  • Second, EPA found that the combined emissions of the six greenhouse gases listed above from new motor vehicles and motor vehicle engines contribute to the atmospheric concentrations which endanger the public health and welfare.

EPA's findings are based on its examination of current scientific research, including that from the U.S. Climate Change Science Program and the Intergovernmental Panel on Climate Change. The findings are based on EPA's assessment of increases in morbidity and mortality due to an increase in the number and intensity of severe heat waves, as well as increased risks of respiratory infection, asthma aggravation and premature death due to worsened regional ozone, which is exacerbated by increased temperatures. In making this new endangerment finding, EPA also pointed to the impacts of climate change on the severity of storms, especially along the Gulf and Atlantic coasts, and on the intensity of precipitation events.

Implications of the Endangerment Finding

Yesterday's endangerment finding was timed to coincide with the opening of the climate talks in Copenhagen, Denmark, and signals the first step to broader regulation of greenhouse gas emissions under the Clean Air Act. Although these findings do not themselves impose any requirements on the automobile industry or others, this action is a prerequisite to finalizing the EPA's proposed greenhouse gas emission standards for motor vehicles, which were jointly proposed by EPA and the Department of Transportation's National Highway Safety Administration on September 15, 2009.

While any other regulation of greenhouse gases would be subject to further notice and comment, the endangerment finding for mobile sources does set in motion a chain of events that could—in the absence of legislation—result in the sweeping use of existing Clean Air Act authorities to regulate greenhouse gas emissions.

The Regulation of GHG Emissions Under Title I of the Clean Air Act

EPA's final endangerment finding for motor vehicles, as a practical matter, may compel EPA to establish greenhouse gas regulations under other parts of the Clean Air Act. Under Title I of the Act, for example, EPA is required by Section 108 to establish national ambient air quality standards ("NAAQS") when the Agency determines that emissions of an air pollutant "cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare" and where "the presence of [such pollutant] in the ambient air results from numerous or diverse mobile or stationary sources." 42 U.S.C. 7408(a)(1). Indeed, anticipating this final endangerment finding, the Center for Biological Diversity and 350.org petitioned EPA on December 2, 2009, to designate greenhouse gases as "criteria" air pollutants and to cap atmospheric carbon dioxide at 350 parts per million (ppm). To view this petition, please follow the following link: Click Here

Although EPA has not publicly stated that it intends to establish an air quality standard for greenhouse gases, such standards will almost certainly result from yesterday's endangerment finding. There is a near-perfect correlation in the language used by the regulatory triggers in the mobile source and NAAQS sections of the Clean Air Act, making it difficult for the Agency to explain why it found that greenhouse gas emissions from mobile sources trigger an endangerment finding under Section 202(a), but failed to find that the presence of greenhouse gases in the ambient air "results from numerous or diverse mobile or stationary sources" so as to drive an endangerment finding under Section 108.

Endangerment Finding & Prevention of Significant Deterioration Permitting

In other areas, EPA already has taken steps to cabin the otherwise sweeping regulatory impact of the endangerment finding. On September 30, 2009, EPA proposed a new rule that will regulate greenhouse gas emissions from stationary sources under the Prevention of Significant Deterioration ("PSD") program and the Title V operating permit program.

The PSD program is part of EPA's preconstruction permitting program for new sources of air pollution. These statutory requirements are triggered by regulation of a pollutant under any other section of the Act and generally require preconstruction review and permitting for "major stationary sources," a term which captures most refineries and factories. Impacted stationary sources will be required to demonstrate the use of best available control technologies ("BACT") and energy efficiency measures to minimize greenhouse gas emissions when facilities are constructed or significantly modified.

EPA characterized this proposal as a "tailoring" rule. Anticipating that EPA's eventual regulation of greenhouse gas emissions from motor vehicles will trigger PSD and Title V applicability requirements, the rule "resets" the Clean Air Act's current statutory thresholds for regulating pollutants under PSD from 100 or 250 tons per year to 10,000 and 25,000 tons per year for greenhouse gases specifically. While the lower statutory thresholds are appropriate for other pollutants, EPA says that they are not feasible for greenhouse gases, which are emitted in much larger quantities. The agency justifies this proposal by stating that the "judicial doctrine of 'absurd results' [and 'administrative necessity'] authorizes departure from a literal application of statutory provisions."

Similarly, under the Title V operating permit program, EPA has proposed a major source emissions applicability threshold of 25,000 tons per year of carbon dioxide-equivalent (CO2e) for existing industrial facilities.

Both the Title V and PSD provisions on greenhouse gases will take effect when the new motor vehicle greenhouse gas emissions rule is finalized in March 2010.

EPA Expresses a Preference for Comprehensive Legislation

Perhaps recognizing that existing regulatory programs under the Clean Air Act are ill-suited for regulating greenhouse gas emissions, EPA's press release reiterates that both "President Obama and Administrator Jackson have publicly stated that they support a legislative solution to the problem of climate change and Congress' efforts to pass comprehensive climate legislation." The House Energy and Commerce Committee introduced such legislation in May of 2009. The bill, "The American Clean Energy and Security Act of 2009," provides for the addition of a new Title VII to the Clean Air Act establishing a greenhouse gas cap-and-trade system that would reduce greenhouse gas emissions to 17% below 2005 levels by 2020 and 83% below 2005 levels by 2050. It passed in the House of Representatives by a narrow margin on June 26, 2009 and was placed on the Senate legislative calendar on July 27, 2009. Likewise, the "Clean Energy Jobs and American Power Act," was introduced in the Senate by Senators Boxer and Kerry on September 30, 2009. The most recent version of both of these bills attempt to eliminate the problem of applying ill-fitting portions of the Clean Air Act to greenhouse gases by exempting greenhouse gases from being listed as criteria or hazardous air pollutants under Sections 108 or 112, respectively, or being subject to Title V permitting requirements.


EPA's endangerment finding is a first step in regulating greenhouse gases under the Clean Air Act. The next step for EPA will be to finalize the proposed greenhouse gas emissions standards for motor vehicles. Should the Agency do so, and, if Congress does not intervene and enact comprehensive climate change legislation, EPA may confront a nondiscretionary obligation to regulate greenhouse gas emissions under other parts of the Clean Air Act.



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Gibson Dunn attorneys Stacie B. Fletcher and Rebecca Gray contributed to this issue of the Climate Change Newsletter.

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EPA Finds That Greenhouse Gases Endanger the Public Health and Welfare