Researchers conducted the first large-scale study of the effects of trees on human health through air pollution removal.
The study, a collaborative project by U.S. Forest Service scientists, concluded that 850 human lives every year are saved from trees. It also calculated that 670,000 cases of acute respiratory symptoms are prevented by trees' pollution removal.
Surprisingly, however, that removal amounts to an average improvement in air quality of less than one percent. Yet the researchers claim that the small number is deceiving--the impacts are actually quite sizeable.
The study, which was published in the journal Environmental Pollution, says that effects of air pollution reduction on human health amount to $7 billion a year.
"Trees remove substantial amounts of pollution and can produce substantial health benefits and monetary values across the nation," the study concludes.
The benefits to our health are, as per the study, much more consequential in urban areas than in rural areas, though the pollution removal itself is higher in rural areas than urban areas.
"With more than 80 percent of Americans living in urban area, this research underscored how truly essential urban forests are to people across the nation," said Michael Rains, Direction of the Forest Service's Northern Research Station, in a press release.
Pollution removal was analyzed by honing in on four major pollutants established by the U.S. Environmental Protection Agency to be harmful to air quality: nitrogen dioxide, ozone, sulfur dioxide and any particles with a diameter less than 2.5 microns. The health consequences from air pollution considered in the study were pulmonary, cardiac, vascular and neurological damages.
The press release states that in the U.S., 130,000 deaths related to particulate matter and 4,700 deaths related to ozone occurred in 2005 as a result of air pollution.
"In terms of impacts on human health, trees in urban areas are substantially more important than rural trees due to their proximity to people." Said Dave Nowak, one of the study leaders. The bottom line the study seems to get at is that the higher the population of both trees and humans, the more numerous the human health (and economic) benefits. And those benefits, as per the researchers, are quite significant.