Two types of air pollution are especially dangerous to breathe—ozone (smog) and particle pollution (soot). The American Lung Association State of the Air 2007 report grades communities across the nation based on the number of days they have unhealthful levels of air pollution. The grades come from the color-coded alert system called the Air Quality Index, which may be familiar from newspaper, radio, television and on-line weather forecasts.
Read more about Harris County OR Pick another county and see which have the higher air quality scores. (Brewster and Webb counties seem to have the only "A's" in Texas.)