U.S. Forest Service Northern Research Station scientists found that pollution removal is substantially higher in rural than in urban areas, but that the effects on human health are substantially greater in urban than in rural areas.
Nowak, D; Greenfield, E.
US Forest Service Northern Research Station Research Review, Vol. 26, April 2015
U.S. Forest Service scientists and collaborators calculated that trees are saving more than 850 human lives a year and preventing 670,000 incidences of acute respiratory symptoms.