Max Dunn, October 2008
BUS-183, Sustainable Design 

In October 1948, a thick cloud of air pollution formed above the industrial town of Donora, Pennsylvania. The cloud which lingered for five days, killed 20 people and caused sickness in 6,000 of the town's 14,000 people.

Events like these lead the US Congress to pass the Clean Air Act (CAA) in 1963 which established funding for the study and the cleanup of air pollution. But there was no comprehensive federal response to address air pollution until Congress passed a much stronger Clean Air Act in 1970. That same year Congress created the EPA and gave it the primary role in carrying out the law. Since 1970, EPA has been responsible for a variety of Clean Air Act programs to reduce air pollution nationwide.

In 1990, Congress dramatically revised and expanded the Clean Air Act, providing EPA even broader authority to implement and enforce regulations reducing air pollutant emissions. The 1990 Amendments also placed an increased emphasis on more cost-effective approaches to reduce air pollution.

Under the Clean Air Act, EPA sets limits on certain air pollutants for the entire United States. This helps to ensure basic health and environmental protection from air pollution for all Americans. The Clean Air Act also gives EPA the authority to limit emissions of air pollutants coming from sources like chemical plants, utilities, and steel mills. Individual states or tribes may have stronger air pollution laws, but they may not have weaker pollution limits than those set by EPA.

Since 1970, the six commonly found air pollutants have decreased by more than 50 percent, air toxics from large industrial sources, such as chemical plants, petroleum refineries, and paper mills have been reduced by nearly 70 percent, new cars are more than 90 percent cleaner, and production of most ozone-depleting chemicals has ceased.[1]

The EPA found that from 1970 to 1990 many positive consequences occurred in the U.S. economy because of Clean Air Act programs and regulations. While the total costs were $523 billion for this 20-year period, the total benefits equaled $22.2 trillion. So overall, the benefits of the Clean Air Act were 42 times greater than the costs.[2]

Here are some graphs showing the reductions in pollutants nationwide from 1980 to 2007.[3]