"As the 113th Congress continues consideration of air quality issues, oversight of Environmental Protection Agency (EPA) regulatory actions is expected to remain the main focus. Of particular interest are EPA's Clean Air Act regulations on emissions of greenhouse gases. President Obama's June 25, 2013, announcement of initiatives to address climate change and EPA's subsequent proposal of GHG emission standards for new fossil-fueled power plants sparked renewed interest in the issue. Air quality has improved substantially in the United States in the 40 years of EPA's Clean Air Act (CAA) regulation. According to the agency's science advisers and others, however, more needs to be done to protect public health and the environment from the effects of air pollution. Thus, the agency continues to promulgate regulations using authority given it by Congress in CAA amendments more than 20 years ago. Members of Congress from both parties have raised questions about the cost-effectiveness of some of these regulations and/or whether the agency has exceeded statutory authority in promulgating them. Others in Congress have supported EPA, noting that the Clean Air Act, often affirmed in court decisions, has authorized or required the agency's actions. EPA's regulatory actions on GHG emissions are the main focus of congressional CAA interest. Although the Obama Administration has consistently said it would prefer that Congress pass new legislation to address climate change, in the absence of such legislation, EPA has developed GHG emission standards using its existing CAA authority."
CRS Report for Congress, R42895