The Effects of Pollution on Trees

Air Pollution Harms Trees

Trees need CO₂ but are damaged by pollutants like sulfur dioxide and oxidants (USDA). Pollution causes browning, damage, and premature death.

Major Pollutants and Impacts

Smog

Causes chlorosis. Blows into pine forests (San Bernardino Mts, CA; Blue Ridge Mts, VA) → browning, premature needle drop. Increases pest susceptibility, shortens lifespan.

Ozone

Forms from car pollution + sunlight. Damages deciduous and coniferous trees: slow growth, browning leaves, mottled needles. Affected species: white ash, aspen, Ohio buckeye, Kentucky coffee, Crimean linden, imperial honey locust, weeping willow, hybrid poplar (Colorado State University).

Sulfur Dioxide

From burning coal/smelting ores. Main cause of acid rain. Damages deciduous and coniferous trees: leaf/needle damage (e.g., orange pine needle tips). Can harm trees in 3–4 days of exposure.

Mitigation

Plant pollution-tolerant species in urban areas. Advocate for cleaner air policies. Maintain tree health to improve resilience.