A recent study by urban forestry guru David Nowak and other researchers at U.S. Forest Service and The Davey Institute found that urban trees save at least one life per year in most cities and up to 8 people per year in large metropolises like New York City.

“Trees growing in cities help clean the air of fine particulate air pollution — soot, smoke, dust, dirt — that can lodge in human lungs and cause health problems,” Grist explains. As an example, “trees clear 71 tons” of air particulate matter 2.5 micrometers in diameter (PM2.5) from Atlanta’s air each year.

As explained in a recent post on outdoor air pollution, urban particulate air pollution kills as many as 2.5 million people each year. PM 2.5 has a drastic effect on human health, including premature mortality.

Researchers noted that larger particles between particulates 2.5 to 10 micrometers in diameter—also called…