Chesapeake VCE Publication Number 430-022, posted January 2000 Conditions in urban environments place trees under numerous stresses including compacted soil, soil moisture extremes, and reduced soil fertility.
Polluted air is another stress that contributes to the decline of urban trees.
Long-term damage may predispose trees to other disorders, making diagnosis difficult. Acute gaseous pollutant damage to red maple leaves. Gaseous pollutants, such as ozone and sulfur dioxide, enter plants through natural openings, usually stomates, and react within leaf tissues to inhibit photosynthesis. Acute damage levels can be high enough to cause sudden tissue damage and death. Chronic damage occurs when small amounts of toxic gases enter leaves and do not initially cause tissue death, but inhibit leaf functions.