Regulation of greenhouse gases under the Clean Air Act

The, United States Environmental Protection Agency (EPA) began regulating greenhouse gases (GHGs) under the Clean Air Act ("CAA" or "Act") from mobile and stationary sources of air pollution for the first time on January 2, 2011. Standards for mobile sources have been established pursuant to Section 202 of the CAA, and GHGs from stationary sources are currently controlled under the authority of Part C of Title I of the Act. The basis for regulations was upheld in the United States Court of Appeals for the District of Columbia in June 2012. Various regional climate change initiatives in the United States have been undertaken by state and local governments, in addition to federal Clean Air Act regulations. History Initial petition and initial denial Section 202(a)(1) of the Clean Air Act requires the Administrator of the EPA to establish standards "applicable to the emission of any air pollutant from…new motor vehicles or new motor vehicle engines, which in [her] judgment cause, or contribute to, air pollution which may reasonably be anticipated to endanger public health or welfare" (emphasis added). On October 20, 1999, the International Center for Technology Assessment (ICTA) and several other parties (petitioners) petitioned the EPA to regulate greenhouse gases from new motor vehicles under the Act. The petitioners argued that carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and hydrofluorocarbons meet the definition of an air pollutant under section 302(g) of the Act, and that statements made by the EPA, other federal agencies, and the United Nations Intergovernmental Panel on Climate Change (IPCC) amounted to a finding that these pollutants are reasonably anticipated to endanger public health and welfare. Based on these factors, the petitioners asserted that EPA had a mandatory duty to regulate greenhouse gases under section 202 of the Act, and asked the agency to carry out that duty.