Global warming is the central environmental challenge of our time. In 2007 in Massachusetts v. EPA, the Supreme Court ruled that global warming pollutants were covered by the Clean Air Act and directed the EPA to determine whether the continued emission of such pollutants endangered the country's public health and welfare. In December 2009, the EPA issued this "endangerment finding," concluding that, based on the best science, global warming pollution presents a clear threat to public health and welfare. The endangerment finding was the scientific determination necessary to allow the agency to start limiting global warming pollution under the Clean Air Act.

Representatives introduced eight bills to block, weaken, or delay the EPA's implementation of the Clean Air Act to reduce harmful global warming pollution. These bills fall into three categories: Congressional Review Act disapproval resolutions to overturn the EPA's science-based endangerment finding, legislation declaring that greenhouse gases are not pollutants subject to the Clean Air Act, and legislation delaying the EPA's actions to reduce carbon pollution from the nation's biggest stationary sources of pollution, like coal plants and oil refineries. The four disapproval resolutions (H.J. Res. 66, H.J. Res. 76, H.J. Res. 77, H. Res. 974) would, for the first time, substitute Congress' political judgment for the EPA's scientific judgment on the public health threat posed by pollution. The three bills (H.R. 391, H.R. 4396, H.R. 4572) declaring that greenhouse gases are not pollutants under the Clean Air Act would reverse the Supreme Court's landmark 2007 decision. The bill to delay the EPA's actions (H.R. 4753) would put a stop-work order on the EPA's commonsense steps to reduce carbon pollution from power plants and refineries, among other large polluters. These harmful bills would overturn sound science, threaten public health, increase our dependence on oil, and block long-overdue action to address climate change and to hold the nation's biggest polluters accountable.

201 representatives cosponsored one or more of these Dirty Air Acts during the 111th Congress. Cosponsorship is the anti-environment action. None of these bills came to a vote in the House. However, Senator Lisa Murkowski (R-AK) offered a disapproval resolution (S.J. Res. 26) to overturn the EPA's endangerment finding, which was defeated on June 10.