Within the past couple years, several states and organizations have filed toxic gas lawsuits against the US Environmental Protection Agency (EPA). The central argument centers on the interpretation of the 1970 Clean Air Act, how to define and regulate "air pollutants", and if it is the responsibility of the EPA to do so.

The first of these lawsuits was filed back in 2005 in the D.C District Court of Appeals by groups such as the Sierra Club and the Environmental Integrity Project. The toxic gases under question in this lawsuit were the harmful pollutants emitted from concentrated animal feeding operations which include ammonia gas, hydrogen sulfide, and fine dust particles. The plaintiffs argue that these feeding operations are not like traditional family farms of the past, but are instead very large corporate run operations which pack large numbers of animals into very small spaces.

The result is the emission of these toxic gases in large quantities into the environment on a yearly basis which have all been linked to causing respiratory illness. In its defense, the EPA claims that it is working with the Bush Administration as part of the sweetheart deal to monitor the progress of these concentrated animal feeding operations to clean up their acts on their own over a number of years.

This wait and see approach is what led to the next set of toxic gas lawsuits filed against the EPA, although this time the issue was emissions gas and global warming. This most recent lawsuit was filed towards the end of 2006 and names California, New Hampshire, Pennsylvania, Illinois, Maine, Massachusetts, Rhode Island, Connecticut, New Jersey, New York, Washington, Vermont, and Oregon, as well as Baltimore, the District of Columbia, and the Sierra Club as plaintiffs.

The argument is whether or not carbon dioxide is considered an air pollutant leading to global warming, and if the EPA should be doing more to regulate carbon dioxide emissions. The plaintiff's case is that carbon dioxide must be considered an air pollutant since it has been scientifically proven to be the principal greenhouse gas affecting global warming. They feel that this definition of carbon dioxide as a threat to public safety puts it within the jurisdiction of the EPA under the Clean Air Act and they have a responsibility to regulate it via cleaner burning cars.

The Bush Administration and the EPA tried to argue that carbon emissions were beyond the control of the EPA as outlined in the Clean Air Act. The section of the Clean Air Act under debate was the wording that it is the responsibility of the EPA administrator to set emission standards for "any air pollutant" from motor vehicles which in his/her judgment contributes to air pollution and affects public health/welfare.

The Administrations approach for emissions was the same as with the concentrated animal feeding operations: do nothing and let the major auto companies work amongst themselves to find a solution to the carbon dioxide problem. The EPA administrator also debated whether man made carbon dioxide emissions was the real cause of global warming, despite existing scientific evidence which already supports this theory. This lawsuit was debated by lower courts trying to decide if the plaintiffs had legal standing, and although the District of Columbia Circuit Court ruled in favor of the EPA the case was eventually brought before the Supreme Court. According to the Supreme Court ruling it was decided that the plaintiffs had a valid case, and that under the Clean Air Act carbon dioxide was an air pollutant of public health concern.

The EPA is now obligated to begin limiting tailpipe emissions beginning with the 2009 model year. Part of this process will be reducing the escape of toxic gases from fuel cans by creating a tighter seal on the lids. Automakers will also be restricted to the amount of benzene added to gasoline to ensure proper engine combustion. Benzene is a carcinogen linked to anemia and reduced blood cell counts, and the new measures taking place by 2011 ensure that automakers are taking positive steps to make their vehicles more environmentally friendly.

It is expected to take until 2030 for full compliance on the new measures to take effect, but the EPA feels that these stricter standards will lead to billions of dollars in health care savings and reduced toxic gas emissions by over 300,000 tons.