Clean Air Act

Expanding Reach

The Clean Air Act of 1970 further strengthened the standards and regulations by establishing new standards for ambient air quality, setting new limits on emissions, and providing additional funding for research. Congress did amend the Clean Air Act in 1977, but in the 1970s and 1980s the EPA primarily implemented the policy outlined in the Clean Air Act of 1970 without making major changes. It was not until 1990 that the federal government again modified the Clean Air Act in any significant way. The Clean Air Act of 1990 not only strengthened existing regulations, but it also expanded the reach of the Clean Air Act to cover previously unregulated areas. It set new air quality standards and targeted motor vehicle emissions, toxic air pollutants, acid rain, smog, stratospheric ozone depletion, and interstate emissions. It also created a comprehensive pollution permit system, widely regarded as a great success for environmental economic policy.

During the 1990s, the EPA engaged in an extensive study to assess the effect of the Clean Air Act on the “public health, economy, and environment of the United States.” In 1997, the EPA issued a report on the Benefits and Costs of the Clean Air Act, 1970 to 1990. The report found that emissions of criteria pollutants (sulfur dioxide, nitrogen oxides, carbon monoxide, particulate matter, ozone, and lead) had declined 30 to 100 percent. The report also found that these declines greatly increased intelligence quotient and reduced mortality, hypertension, and a number of other adverse health effects. They also improved visibility and avoided significant damage to agricultural crops. The report estimated a benefit-cost ratio of between 10.7 and 94.5, with a mean estimate of 42. This and other evidence indicate that the Clean Air Act has dramatically improved environmental quality and health in the United States, and that it has done so at relatively low cost.

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