WASHINGTON - Carbon dioxide, the chief cause of global warming, cannot be regulated as a pollutant, the Environmental Protection Agency ruled yesterday.
The decision, which reverses a 1998 Clinton administration position, means the Bush administration won't be able to use the Clean Air Act to reduce carbon-dioxide emissions from cars.
If the Bush administration had decided that carbon dioxide is a pollutant and harmful, it could have required expensive new pollution controls on new cars and perhaps on power plants, which together are the main sources of so-called greenhouse gases.
Environmentalists are expected to respond by suing the EPA to try to force it to regulate carbon dioxide. The fight is likely to shift to Congress, where lawmakers are proposing a law giving the EPA clear authority to regulate emissions of gases that cause global warming.
"Refusing to call greenhouse-gas emissions a pollutant is like refusing to say that smoking causes lung cancer," responded Melissa Carey, a climate policy specialist for Environmental Defense, a moderate New York-based environmental group.
EPA General Counsel Robert Fabricant took the opposite position in his 12-page decision yesterday. "Because the [Clean Air Act] does not authorize regulation to address climate change," Fabricant wrote, "it follows that [carbon dioxide] and other [greenhouse gases], as such, are not air pollutants."
EPA officials said they relied heavily on a 2000 U.S. Supreme Court ruling that said the FDA overreached when it tried to regulate tobacco as a drug.
Jonathan Cannon, the Clinton EPA general counsel who wrote the now-reversed 1998 decision, said: "They're trying to put a stake in the heart for any possible existing avenue for dealing with global climate change either by this administration or any future administration."
Auto industry representatives lauded Fabricant's position.
"Why would you regulate a pollutant that is an inert gas that is vital to plant photosynthesis and that people exhale when they breathe?" said Eron Shosteck, a spokesman for the Alliance of Automobile Manufacturers, a Washington-based car industry lobby.
While carbon dioxide does no direct damage to people, plants or animals, scientists say it causes harm indirectly, because global warming - increases in the atmosphere's temperature triggered by gases that trap sunlight - damages ecosystems. Carbon dioxide is by far the leading culprit.
The Clean Air Act says the EPA can regulate a substance if it comes from cars, contributes to pollution and "may reasonably be anticipated to endanger public health or welfare." The law broadly defines an air pollutant as "any air pollution agent or combination of agents which is emitted into or otherwise enters the ambient air."