The federal Clean Air Act, originally passed in 1963 and amended in 1970 and 1990, has forced the spending of hundreds of billions of dollars because air pollution supposedly poses a serious threat to human health, and without regulation air quality would rapidly deteriorate. However, scientific data available at the time showed that air quality was improving significantly before the legislation was enacted.

Observational data available from Continuous Air Monitoring Project stations set up in 1962 in six major cities - Chicago, Cincinnati, Denver, St. Louis, Philadelphia and Washington - and from National Air Sampling Network stations established earlier showed that in those urban areas:

• Concentrations of settleable dust fell between 1925 and 1965.

• Levels of sulfur dioxide fell between 1962 and 1968.

• Total oxidants (ozone) fell between 1964 and 1968.

• Carbon monoxide levels fell in four cities and rose in two between 1963 and 1968.

Data from the National Air Sampling Network also showed that:

• Between 1957 and 1966, concentrations of airborne particulates fell in 58 urban areas and were almost unchanged in 20 nonurban areas.

• Between 1962 and 1968, sulfur dioxide levels at 22 urban sites fell.

In fact, the trend toward cleaner air was driven by technological change, as well as state and local pollution controls, increasing electrification and a shift from manufacturing to service industries. Similar changes were occurring in other countries. For example, the average winter smoke levels recorded in London had been falling since the 1920s.

Source: Hugh W. Ellsaesser, "The Misuse of Science in Environmental Management," Policy Study No. 70, December 8, 1995, Heartland Institute, 800 E. Northwest Highway, Suite 1080, Palatine, IL 60067, (707) 202-3060.