An official website of the United States government.

We've made some changes to If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

Visibility and Haze

Visibility in Parks and Wilderness Areas

Since 1988, the EPA, States, and Federal land management agencies have conducted monitoring of air pollution and visibility impairment at a number of national parks and wilderness areas across the United States.