While the presence of trees has long been associated with better health, you probably didn’t think that removing them entirely could straight-up kill you. But that's what a new report in the American Journal of Preventive Medicine says.
The study, undertaken by the U.S. Forest Service, tracked the 2002 outbreak of the emerald ash borer, an invasive beetle that infests all 22 species of North American ash and is almost always fatal for trees. They found that in the 15 states where the ash borer had devastated tree populations, 15,000 more people died from cardiovascular disease and 6,000 more from lower respiratory disease. The uninfected states experienced no such spike.
U.S. Forest Service researcher Geoffrey Donovan went on PBS’s Newshour program to discuss the findings and the unique opportunity afforded researchers when drastic changes take place over such a short period of time. “Imagine if you were trying to look at the effect of trees growing on someone's health and I got 100 people,” he said. “I put them in 100 identical houses, and I planted trees in front of 50 of those houses and then waited. It would take 40 or 50 years before you found anything because trees grow really slowly.”
The results, he said, were staggering in their consistency. “We looked across space and time and saw this repeated over and over again in places with very different demographic make-ups,” he said. “You're seeing it in Michigan but then you're seeing it in Ohio, you're seeing it in Indiana, in New York, Maryland and Tennessee.”
Donovan’s final message? Just plant trees. “I think people intuitively know that,” he stressed. “The idea that trees and humans are linked is as old as humanity.”