US Environmental Protection Agency
Epa: Criteria Air Pollutants
Find out about the six major air pollutants. In-depth descriptions of ozone, nitrogen dioxide, particulates, sulfur dioxide, carbon monoxide, and lead are provided.
US Geological Survey
Usgs: The Effects of Acid Rain
Geology and chemistry of acid rain effects. Lots of building and monument pictures showing acid rain damage. Be sure to follow the "next" link at bottom of each page.