Air pollution poses a serious threat to the coniferous forests of California. Symptoms of air pollution damage to coniferous species have been observed in forests located north and east of the Los Angeles basin, east of major cities in the Central Valley, and east of San Diego. Damage is especially severe in the San Bernardino Mountains east of Los Angeles.

The work upon which this publication is based was performed pursuant to Contract No. 68–03–0273 with the Environmental Protection Agency.