The EPA estimates that between 2007 and 2018 the rule has cut 500,000 tons of sulfur dioxide and 300,000 tons of nitrous ...

An analysis of data from 1999 through 2023 shows 93% of parks and wilderness areas saw improved air quality on clear days.

Congress amended the Clean Air Act in 1977 to make restoring and maintaining visibility a goal for 156 national parks, wilderness areas, wildlife refuges and tribal reservations across 36 states.