Recently, the EPA made a final endangerment finding for carbon dioxide emissions. To understand the endangerment finding, we need to begin with a discussion of the Supreme Court’s decision in Massachusetts v. EPA. The case originated from a petition requesting that the EPA regulate carbon dioxide emissions from new motor vehicles. The EPA denied the petition, saying that the Clean Air Act does not give the EPA authority to issue mandatory regulations to combat climate change. The EPA added that regardless of its authority under the Clean Air Act, it would not be appropriate to do so at the time the petition was filed.
In Massachusetts v. EPA, the Supreme Court reversed the EPA’s decision issued a remand order. The Supreme Court held that carbon dioxide fell within the broad definition of an air pollutant under the Clean Air Act and that §202 (a) (1) of the Clean Air Act authorized the EPA to regulate carbon dioxide emissions from new motor vehicles. The Supreme Court also held that the EPA abused its discretion when it decided not to regulate of its failure to provide a reasoned explanation for its refusal to decide whether carbon dioxide emissions contributes to climate change. Under the Clean Air Act, the EPA can avoid taking further action only if it determines that greenhouse gases do not contribute to climate change or if it provides some reasonable explanation as to why it cannot make an endangerment finding. For example, the EPA could fulfill the “reasonable explanation” requirement by stating that it believes the profound scientific uncertainty around the issue precludes it from making a reasoned judgment as to whether carbon dioxide emissions contribute to climate change. In this case, the EPA made no such statement, but instead relied on policy considerations that had nothing to do whether carbon dioxide emissions contribute to climate change. It is important to note that the Supreme Court’s holding is narrow and that the Supreme Court did not reach the question of whether policy considerations may inform the EPA if it makes a finding that carbon dioxide emissions contribute to climate change, nor did the Supreme Court say whether the EPA must make an endangerment finding.
The Bush Administration took the first step in complying with the Supreme Court’s order by issuing an Advanced Notice of Proposed Rulemaking for Regulating Greenhouse Gas Emissions under the Clean Air Act. However, the notice merely opened up the issue for discussion and did not propose to make an endangerment finding or propose a program for regulating greenhouse gas emissions. Essentially, the notice was a strategy for delaying the process and shifting difficult decisions to the Obama administration.
In April 2009, the EPA responded to the Court by issuing a proposed finding that greenhouse gases contribute to air pollution that may endanger public health or welfare. On September 15, 2009, the EPA issued a proposed rule to control GHG emissions from light-duty motor vehicles under the Clean Air Act. Finalizing the proposed light-duty vehicle regulations is contingent upon EPA finalizing both the endangerment finding and the cause or contribute finding. On December 7, 2009, the EPA issued a final action under the Clean Air Act finding that GHG emissions threaten the public health and welfare. The endangerment and cause or contribute findings will allow the EPA to finalize the proposed GHG standards for light duty vehicles. Once the EPA promulgates regulations under the CAA to control GHG emissions from light-duty motor vehicles it will trigger PSD and Title V applicability requirements for GHG emissions.
On September 30, 2009, the EPA issued a proposal to regulate GHG under the Clean Air Act’s Title V and PSD Programs. Under the proposal, the applicability threshold under the Title V and PSD programs for GHG emissions would be raised to 25,000 tons per year of CO2 emissions. Facilities, such as coal-fired and natural gas-fired power plants, with the potential to emit at least 25,000 tons per year of CO2 emissions would be considered a “major source” for purposes of applying the Title V and PSD programs. The PSD and Title V programs also apply to major sources undertaking modifications that result in an increase of GHG emissions above a “significance level.” The EPA is proposing that this significance level be set at somewhere between 10,000 and 25,000 tons per year.
Under the PSD program, one of the principal requirements is that a new major source or major modification must apply BACT, which is determined on a case-by-case basis taking into account, among other factors, the cost and effectiveness of the control. The EPA has developed a “top-down” approach for BACT review which involves a decision process that includes identification of all available control technologies, elimination of technically infeasible options, ranking of remaining options by control and cost effectiveness, and then selection of BACT. Under PSD, once a source is determined to be major for any regulated pollutant, a BACT review is performed for each attainment pollutant whose emissions exceed its PSD significance level as part of new construction or modification projects at the source.
In addition to performing a BACT review, the source must analyze the impact of the project on ambient air quality to assure that no violation of any NAAQS or PSD increments will result, and must analyze impacts on soil, vegetation, and visibility. There are currently no NAAQS or PSD increments established for GHGs, and therefore these PSD requirements would not apply to GHG emissions sources, even when PSD is triggered for GHG emissions sources. However, as noted previously, if PSD is triggered for a GHG emissions source, all regulated NSR pollutants which the new source emits in significant amounts would be subject to PSD requirements. Therefore, if a facility triggers review for regulated NSR pollutants that are non-GHG pollutants for which there are established NAAQS or increments, the air quality and additional impacts would apply to those pollutants.
Posted by nathanrpaine 
