Air pollution can damage sensitive plants growing in industrial or urban areas. Such injury is widespread and will be seen on more than one plant or more than one property.
The symptoms will vary with the type of pollutant and the severity of the exposure. Air pollution symptoms can mimic other problems, particularly nutrient deficiency, pests, water excess or deficiency, and temperature extremes. This can make diagnosis difficult.
If the suspected source of pollution is a single "point source," look for patterns of injury. The most severe injury should be downwind from the suspected source. Unlike pest problems, which normally concentrate on selected plant species, air pollution will injure many species in the area.
Chemical analysis of the leaves can detect fluorides or chlorides. Chronic exposure to sulfur dioxide can lead to a build-up of sulfur in the leaves. Acute short-term exposures may not cause a build-up, or the sulfur may be leached away by rainfall.