Yesterday marked the 40th birthday of the Environmental Protection Agency’s (EPA) Clean Air Act (CAA), and environmentalists celebrated by reminding us how beneficial the regulation has been at improving air quality in the U.S. Now the EPA wants to turn the Clean Air Act’s birthday party into an all-out rager by allowing them to do what elected officials could not: regulate carbon dioxide (CO2).

First things first. Air quality was improving before the passage of the 1970 CAA. Environmentalists should give more credit to innovation and less to top-down regulation. The air quality improvements are attributable to the cost-saving, energy-efficiency gains made by business and industry that go hand-in-hand with environmental improvement. Engineer and environmental expert Indur Goklany explains:

Nationwide air quality and emissions data from the Environmental Protection Agency shows that air quality was already improving rapidly before federalization. The improvements were especially pronounced in urban areas, which had the worst pollution problems. Sulfur dioxide emissions declined 40 percent between 1962 and 1969. Smog, a problem first and foremost in the Los Angeles area, had been lessening in that region since the 1950s.

National emissions per dollar of gross national product peaked in the 1920s for sulfur dioxide, the 1930s for the volatile organic compounds and nitrogen oxides that produce smog, and the 1940s or earlier for particulate matter and carbon monoxide. At least 70 percent of the reductions between those peaks and the 1997 levels predated federalization.

That hasn’t stopped the EPA from overreaching. The EPA will now use the CAA to regulate CO2 emissions since Congress failed to pass cap-and-trade legislation. A 2007 Supreme Court case decided that CO2 and five other greenhouse gases (GHGs) are pollutants and can be regulated under the CAA. The Court ordered the EPA to determine whether these GHG emissions were dangerous to human health and the environment and whether the scientific consensus on the effects of GHGs was settled. In April 2009, the EPA issued an endangerment finding, saying that current and future GHG emissions pose a serious threat to public health and safety. This will undoubtedly be the most expensive and expansive environmental regulation in history—with no environmental benefit to show for it.

Like cap and trade, regulating CO2 emissions under the CAA would similarly burden the economy with higher energy costs, but doing so in a top-down regulatory fashion would also include higher administrative compliance costs for businesses, higher bureaucratic costs for enforcing the regulations, and higher legal costs from the inevitable litigation.

Air quality is undoubtedly important; who isn’t for clean air? But the means to the end is important as well, and we should pursue policies that allow improvements to occur organically rather than implement policies that prohibit innovation and place higher costs on American families. Congress should rein in the EPA’s regulatory authority by amending the CAA to exclude CO2 and other GHGs from coming under the EPA’s purview.