Federal Endangerment Finding and Cause or Contribute Findings for Greenhouse Gases under the Clean Air Act
Most Recent Action
The EPA’s Office of the Inspector General, on September 28th, criticized the way the EPA reviewed scientific data to support its finding that greenhouse gases should be regulated under the Clean Air Act. The Inspector General’s report suggests the Obama administration cut corners before concluding that climate-change pollution can endanger human health.
In Massachusetts v. EPA, 549 U.S. 497 (2007), the U.S. Supreme Court found that greenhouse gases are pollutants covered by the Clean Air Act. The Court held that the EPA administrator must determine whether emissions of greenhouse gases from new motor vehicles cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare, or whether the science is too uncertain to make a reasoned decision.
As a result of the Supreme Court decision, the EPA issued two new findings that paved the way for the EPA to regulate greenhouse gases under section 202(a) of the Clean Air Act:
The Administrator finds that the current and projected concentrations of the mix of six key greenhouse gases—carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6)—in the atmosphere threaten the public health and welfare of current and future generations. This is referred to as the endangerment finding.
The Administrator also finds that the combined emissions of CO2, CH4, N2O, and HFCs from new motor vehicles and motor vehicle engines contribute to the atmospheric concentrations of these key greenhouse gases and hence to the threat of climate change. This is referred to as the cause or contribute finding.
These findings do not themselves impose any requirements on industry or other entities. However, this action is a prerequisite to finalizing the EPA's proposed greenhouse gas emission standards for light-duty vehicles.
42 U.S.C. Sec. 7521(a)(1) (CAA) – Emission standards for new motor vehicles or new motor engines – This section of the CAA provides the EPA authority to regulate “greenhouse gases”, including CO2.
Massachusetts v. EPA, 549 U.S. 497 (2007): Decided April 2, 2007. U.S. Supreme Court ruling that because greenhouse gases fit within the Clean Air Act’s definition of “air pollutant,” EPA has authority to regulate emission of such gases from new motor vehicles.
40 CFR Chap. 1 – Proposed Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act; Final Rule; December 15, 2009.