SP657 Impacts of Air Pollution on the Urban Forest

An average human breathes around 3,400 gallons of air each day. Included in each breath can be numerous noxious chemicals as well as suspended particles. Consequently, human lungs must cope with this pollution. It is well known that air pollution is hazardous to human health and of enormous concern today. However, the “lungs” of our urban areas, trees growing in and around our cities, must also contend with air pollution. Just as air pollution impacts humans, air pollution affects trees in a variety of ways.

Pollution has long been identified as harmful to trees. Historically, impacts of air pollution were primarily local in scale (trees impacted by a nearby industrial area).Yet today, trees are being affected on both the local and regional scale. Entire urban areas and even rural area trees are experiencing adverse impacts of air pollution.

Trees help cleanse the air by reducing levels of carbon dioxide (CO2) and removing pollutants, while releasing oxygen through photosynthesis. Air pollution directly injures trees by damaging living tissue, primarily foliage, and impairs photosynthesis and the ability to respirate. Air pollutants also weaken trees, predisposing them to further damage by insects and disease. Some air pollutants can also indirectly impact tree health by altering ecosystem processes such as soil chemistry and nutrient cycling. The result is decreased tree vigor and growth that can culminate in tree death.