United States Clean Air Act

The United States Clean Air Act of 1977 set as a national goal the prevention of any future degradation and the reduction of any existing impairment of visibility in mandatory class I federal areas caused by anthropogenic air pollution. The Clean Air Act Amendments of 1990 reinforce the support of these goals. (See Chapter 22 foj a discussion of federal classes of areas.) These areas include most of the major national parks, such as the Grand Canyon, Yosemite, and Zion Park. This portion of the Clean Air Act ad-... 

Amendments to the Unites States Clean Air Act of 1967 were made in 1970 and again in 1990 (United States Congress, 1990) provided for the establishment of national ambient air quality standards for, as an example, sulfur dioxide. 

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