Study suggests a link between trees and human health

File photo courtesy: Radhakrishnan Menon

Monday, June 10, 2013, 5:41 PM -

The presence of trees can have a positive impact on human health, a study published earlier this year by the U.S. Forest Service suggests.

Researchers analyzed 18 years of data from 1,296 counties in 15 U.S. states and found that people living in areas infested with tree-killing beetles suffered 21,000 more cardiovascular and lower respiratory complications and deaths, compared with people living in unaffected areas. 

The emerald ash borer - an invasive species native to Asia an Russia - is responsible for the death of nearly 100 million ash trees in the eastern and midwestern U.S. as well as in Quebec and Ontario.

While adults cause little disruption to the environment, larvae feed on the inner bark of ash trees, destroying them. Trees in Asia and Russia have developed natural defenses, but North American trees have no way to combat the bugs.

Emerald ash borers target all 22 species of North American ash, killing nearly every tree they come into contact with.

Because the insects destroy trees in a relatively short time, researchers were provided with a unique opportunity to examine the impact of significant environmental changes on human health.

"There’s a natural tendency to see our findings and conclude that, surely, the higher mortality rates are because of some confounding variable, like income or education, and not the loss of trees,” said lead study author Geoffrey Donovan in a statement, “but we saw the same pattern repeated over and over in counties with very different demographic makeups."

The link between cardiovascular and lower respiratory diseases and the absence of trees has yet to be determined.