Trees Cleanse City Air

Fine particulate air pollution (particulate matter less than 2.5 microns, or PM2.5) has serious health effects, including premature mortality, pulmonary inflammation, accelerated atherosclerosis, and altered cardiac functions. David Nowak, from the US Forest Service (New York, USA), and colleagues have estimated how much fine particulate matter is removed by trees in 10 cities - Atlanta, Baltimore, Boston, Chicago, Los Angeles, Minneapolis, New York City, Philadelphia, San Francisco, and Syracuse, NY;  their impact on PM2.5 concentrations; and associated values and impacts on human health.      Overall, the greatest effect of trees on reducing health impacts of PM2.5 occurred in New York due to its relatively large human population and the trees’ moderately high removal rate and reduction in pollution concentration. The greatest overall removal by trees was in Atlanta due to its relatively high percent tree cover and PM2.5 concentrations.  Overall, the team submits that urban trees and forests save an average of one life every year per city.  The study authors urge that: “Understanding the impact of urban trees on air quality can lead to improved urban forest management strategies to sustain human health in cities.”