Page "Denver-Aurora-Broomfield, CO Metropolitan Statistical Area" Paragraph 13

The center of the metropolitan area sits in a valley, the Denver Basin, and suffers from air pollution known colloquially as the brown cloud, building up if the air is stagnant as it often is in the winter.

Severity of pollution in this area has varied enormously over the years.

In the late 1980s the area was frequently in violation of multiple National Ambient Air Quality Standards established by the United States Environmental Protection Agency ( EPA ).

The Regional Air Quality Council ( RAQC ) was formed in 1989 to create plans to address the problem.

Through a variety of measures the area's air quality was improved and in 2002 the EPA designated the area in compliance with all federal health-based air quality standards.

Denver was the first major city in the United States to reach compliance with all six of these standards after previously violating five of them Since then the EPA introduced a new standard for small particulates and made the existing ozone standard stricter.

In 2003 the new ozone standard was frequently exceeded in the area and was occasionally exceeded as far away as Rocky Mountain National Park.

The RAQC hopes to implement plans enabling the area to comply with the new standards by 2007.