EPA Proposes Greenhouse Gas Endangerment Finding

Today, the Environmental Protection Agency ("EPA") signed a pre-publication copy of a long-anticipated proposal finding that greenhouse gas ("GHG") emissions from new motor vehicles and their engines cause or contribute to air pollution which may reasonably be anticipated to endanger public health and welfare. This "endangerment finding" is EPA's first step towards regulating GHG emissions under the Clean Air Act ("CAA"). If finalized, the endangerment finding triggers a nondiscretionary duty for EPA to regulate GHG "tailpipe" emissions from mobile sources under CAA Section 202.

EPA's proposed endangerment finding responds to the U.S. Supreme Court's landmark Massachusetts v. EPA decision, in which the Court remanded EPA's denial of a petition to regulate GHGs from motor vehicles. The Court held, 5-4, that GHGs are "air pollutants" under the CAA and directed EPA to make a determination of whether GHGs from motor vehicles contribute to pollution that endangers public health or welfare, or, alternatively, offer a reasoned explanation for why such a determination cannot be made. EPA reportedly prepared an endangerment finding based solely on public welfare in late 2007, but that finding was never released. Today's action proposes a finding that GHGs endanger both public health and welfare. If finalized, this finding will make it easier for petitioners to urge the broader use of the CAA to regulate GHGs from a variety of mobile and stationary sources.

A proposed or final endangerment finding itself does not regulate GHGs, and EPA did not release proposed regulations applying to tailpipe emissions concurrently with today's finding. A final endangerment finding will create, however, a nondiscretionary duty to regulate GHG emissions from motor vehicles, and it will likely have significant implications for regulation under other sections of the CAA, given that many stationary source programs are also triggered upon a similar finding of endangerment. Another provision likely to form the basis for regulation is CAA Section 111, which establishes New Source Performance Standards for sources that cause or contribute significantly to pollution reasonably anticipated "to endanger public health or welfare." A final endangerment finding also has indirect implications for the CAA Prevention of Significant Deterioration ("PSD") permitting program. PSD is triggered whenever a new or modified source emits "regulated air pollutants" above certain thresholds. Thus, although an endangerment finding would not itself cause GHGs to become regulated pollutants subject to PSD, the emission standards that EPA is required to develop as a result of such a finding would.

Once it is published in the Federal Register, the public will have 60 days to submit comments on the proposal. A final decision could be made by the end of this year.