Urban trees save lives by reducing pollution

Trees save the lives of about eight New Yorkers per year by boosting the city’s air quality, according to a study in Environmental Pollution.

The researchers looked specifically at particles less than 2.5 microns, which can increase the risk of conditions such as atherosclerosis and lung inflammation. The team calculated the likely effects of tree cover on the health of residents in 10 cities, including New York, Los Angeles, Chicago, San Francisco, and Minneapolis.

Trees removed 4.7 to 64.5 tonnes of these particles from the air per year, a service worth $1.1 million to $60.1 million, the authors say. They estimate that the reduction in pollution prevented about one death per year in each city; that figure went up to 7.6 in New York, partly because so many people live there. Trees in Los Angeles were less effective at cleaning the air because lack of rain keeps the particles from washing off leaves. — Roberta Kwok | 21 June 2013

Source: Nowak, D.J. et al. 2013. Modeled PM2.5 removal by trees in ten U.S. cities and associated health effects. Environmental Pollution doi: 10.1016/j.envpol.2013.03.050.

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