|Santa Barbara's Oak Park. DT LANGE|
• Poor air quality affects 127 million people in the United States.
• Air pollution can significantly affect human and ecosystem health.
• Trees and parks affect air pollution by:
– Reducing air temperatures and consequently pollutant emissions
– Directly removing pollution from the air
– Emitting chemicals that contribute to pollution formation
• Pollution removal by U.S.urban park trees is on the order of 75,000 tons per year.
Removal of air pollutants
Trees remove gaseous air pollution primarily by uptake through the leaves, though some gases are removed by the plant surface.Trees also remove pollution by intercepting airborne particles.Many of the particles that are intercepted are eventually resuspended back to the atmosphere, washed off by rain, or dropped to the ground with leaf and twig fall.
Healthy trees in cities can remove significant amounts of air pollution.The amount of pollution removed is directly related to the amount or air pollution in the atmosphere.(If there is no air pollution, the trees will remove no air pollution.) Areas with a high proportion of tree cover (e.g., parks) will remove more pollution and have the potential for greater reduction in air pollution concentrations in and around these areas.
Air Quality Effects of Urban Trees and Parks www.NRPA.org