The U.S. Environmental Protection Agency released this overview of proposed actions following a study regarding greenhouse gas emissions on April 17, 2009. The summary states,
"Today, the Administrator signed a proposal with two distinct findings regarding greenhouse gases under section 202(a) of the Clean Air Act:
- Endangerment Finding: The Administrator is proposing to find 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.-
-Cause or Contribute Finding: The Administrator is further proposing to find 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."