IMPROVE

Visibility regulations & trends

On a clear day, you used to be able to see forever

The natural visual range in the United States varies from about 140 miles in western states to 90 miles in eastern states. However, emissions generated by human activity have greatly reduced these historical vistas. In the West, average visibility is now only 33 to 90 miles, with even more significant reductions in the East, where average visibility is just 14 to 24 miles.

IMPROVE

Interagency Monitoring of Protected Visual Environments

Visible air pollution contains particles that block visibility, cause health problems for humans and wildlife, and damage environments and infrastructures. In 1985, the EPA created the IMPROVE network along with UC Davis air quality researchers at Crocker Nuclear Lab.