Visibility in the United States

Visibility in Environmental Law

An air quality value relating to pollutants that af feet the ability to see clearly. In 1977, Congress added a provision to the Clean Air Act to regulate manmade visibility problems for Class I areas, such as international parks, national wilderness areas, national parks, and national monuments.

Air pollution sources near Class I areas must use the best available retrofit technology if they interfere with visibility. New sources must obtain a permit, and the EPA is required to consider how the proposed activity will affect visibility. The federal land manager for the Class I area, either the National Park Service or the Forest Service, can participate in the permitting process, and they often insist on an offset of visibility impacting pollutants to ensure that the new source will not cause a visibility problem.
Based on “Environment and the Law. A Dictionary”.