In some areas, injury on certain species has been serious and has represented a limiting production factor. This type of damage is more noticeable, but probably not as great as the sub-lethal chronic injury that occurs over much larger areas.
Chronic damage is more difficult to diagnose and evaluate.
Diagnosticians should be aware that pollutants are mixed in the atmosphere and that these mixtures may produce symptoms that vary from those caused by a single compound under laboratory conditions. Pollutant Source Symptoms Ozone Nitrogen dioxide and Four different kinds of hydrocarbons emitted from symptoms can result from automobiles, industrial ozone exposure. The most combustion, oil refineries common symptom is localized and many lesser sources thickening and pigmentation react with sunlight to of the cell walls causing form ozone. During sharply defined small dot- electrical storms, ozone like lesions. General is produced and can be upper surface bleaching is brought down from the another common type of upper atmosphere by injury.