By Nancy Penrose
In the urban landscape, trees shade the sidewalks, absorb air pollution, lessen traffic noise, and also happen to be nice to look at. And of course trees take carbon dioxide in the air and convert it to oxygen, which we mammals kind of need for breathing.
But it also turns out that trees can help you live longer.
A recent research study conducted in Portland by the US Forest Service, found that in neighborhoods where a nonprofit was planting more trees, fewer people died.
Geoffrey Donovan, the Forest Service researcher who did the study, which was published in the December issue of the journal Environment International, stated “Urban trees are an essential part of our public health infrastructure, and they should be treated as such.”
Green health care
For three decades, the Portland area nonprofit organization Friends of Trees planted nearly 50,000 oaks, dogwoods and other types of trees around the city. Between 1990 and 2019, Friends of Trees planted 49,246 street trees (and kept records of where they were planted and when). The research team looked at the number of trees planted in a given area, in the preceding 5, 10, or 15 years. They compared this information with death rates due to cardiovascular, respiratory, or non-accidental causes in that same area, using data from the Oregon Health Authority.
Using a mathematical model to remove factors such as race, income, age and education, the study found that for every 100 trees planted, there was approximately one fewer non-accidental death per year. So 50,000 trees planted equated to 500 fewer non-accidental deaths per year.
Yashar Vasef, executive director of Friends of Trees, which plants across six counties in Oregon and Washington, stated “Across the board, the benefits of trees are astounding. And they come at a lower cost than many other solutions.”
As the trees got older and taller, the mortality rates among nearby people went down, the study found.
Geoffrey Donovan from the US Forest Service stated “Bigger trees, bigger impact on mortality, which is what you would expect. Studies have found links between exposure to the natural environment and improved health in a wide range of different cities and countries. We certainly know that air pollution, stress, and sedentary behavior are bad for people no matter their race or socioeconomic status.”
The reverse, unfortunately, seems to be true, too. Mortality rates appear to go up in areas that lose tree cover.
In an earlier study, Donovan and his team saw an increase in deaths from cardiovascular and lower-respiratory-tract illnesses in areas from Minnesota to New York that lost trees from a pest called the emerald ash borer.
More trees, fewer deaths
Another recent study published in the British medical journal The Lancet suggested that a third of deaths from a 2015 heat wave in Europe could have been prevented with 30% more tree cover.
There are several reasons trees could boost health, including better air quality and increased levels of oxygen, less stress, and increased physical activity among residents of tree-lined neighborhoods. The link between more trees and lessening death rates held in both already heavy tree population neighborhoods, which tend to be more prosperous, and neighborhoods with fewer trees, which tend to be poorer.
The US Forest Service study stopped short of saying there was a direct cause-and-effect relationship between trees and death rates. But the statistics are pretty convincing and make for a safe bet.
Nancy Penrose is the owner of Big Trees Inc., located in Snohomish, WA in the Seattle area. The company is one of the largest tree nurseries in the Seattle area with over 120,000 trees available in over 300 varieties. They not only deliver young trees, but also mature trees in a wide range of sizes. Some types of trees available include spring flowering, deciduous, evergreen, and privacy trees. The company also does tree transplanting including large trees. Their blog can be seen at https://bigtreesupply.com/blog/ or http://arboristblog.com/. They can be reached at 360-563-2700.