The legislation was intended to protect and enhance the quality of this Nation's air resources and to protect the health and welfare of the general public. The legislation directed the EPA Administrator to establish national primary and secondary ambient air quality standards for the identified air pollutants. Primary standards were set to protect public health while secondary standards were set at a level that would protect the public's welfare from any known or anticipated adverse effects of a pollutant. These included effects on soils, water, crops, vegetation, manmade materials, wildlife, animals, weather, visibility, climate, damage to and deterioration of property, hazards to transportation, and the effects on economic values and on personal comfort and well-being. SIPs contain specific guidelines to reduce emissions.
States can also reduce or eliminate the use of prescribed fire in non-attainment areas.
Most importantly though, the Clean Air Act of 1970 provided Federal enforcement when non-attainment appeared to be caused by a State's failure to enforce its State Implementation Plan. A mendments to the Clean Air Act in 1974 and 1977 provided for the prevention of significant deterioration of air quality in those areas where air quality was already superior to the national standards. Areas where air quality was already above the national standards were designated as Class I areas. The areas included all international parks, all national parks greater than 6,000 acres, all national wilderness areas, and memorial parks exceeding 5,000 acres . Protection of visibility was an important aspect of the 1974 and 1977 amendments to the Clear Air Act.