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class I area

Under the Clean Air Act, a class I area is one in which visibility is protected more stringently than under the National Ambient Air Quality Standards (NAAQS); it includes national parks, wilderness areas, monuments, and other areas of special national and cultural significance.

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class I area

Under the Clean Air Act, a class I area is one in which visibility is protected more stringently than under the National Ambient Air Quality Standards (NAAQS); it includes national parks, wilderness areas, monuments, and other areas of special national and cultural significance.