Most Polluted Cities

Four of the top five most polluted cities are in California: (1) Los Angeles; (2) Visalia-Porterville; (3) Bakersfield; and (4) Fresno. "The association says more than one-quarter of Americans live in areas where particle pollution reaches unhealthy levels. Almost half live in areas with health-threatening levels of ozone pollution, or smog... Santa Fe, New Mexico, received the best rating on particle pollution, followed by Honolulu, Hawaii; Cheyenne, Wyoming; Great Falls, Montana; and Farmington, New Mexico." The American Lung Association's full report provides a detailed set of charts for various types of particulates, and the map guide provides data by county and state.