While trees' pollution removal equated to an average air quality improvement of less than 1 percent, the impacts of that improvement are substantial. Researchers valued the human health effects of the reduced air pollution at nearly $7 billion every year in a study published recently in the journal Environmental Pollution.
The unique study conducted by Dave Nowak and Eric Greenfield of the U.S. Forest Service's Northern Research Station and Satoshi Hirabayashi and Allison Bodine of the Davey Institute, directly links the removal of air pollution with improved human health effects and associated health values. The scientists found that pollution removal is substantially higher in rural areas than urban areas; however the effects on human health are substantially greater in urban areas than rural areas.
Health effects related to air pollution include impacts on pulmonary, cardiac, vascular, and neurological systems.
"In terms of impacts on human health, trees in urban areas are substantially more important than rural trees due to their proximity to people," Nowak said. "We found that in general, the greater the tree cover, the greater the pollution removal, and the greater the removal and population density, the greater the value of human health benefits."