Problem
What’s an inexpensive, ascetically pleasing way to improve public health?
Solution
Trees in public space, according to a study published in Scientific Reports.
Method
Researchers examined a dataset of public, urban trees in Toronto, which happens to have 530,000 such trees. The data included things like species, location, and diameter. They also looked at anonymized health records of 30,000 Toronto residents, which included heart conditions, mental illness, diabetes, cancer, and more. The residents also reported their own perception of their health. By mapping Toronto’s health problems, comparing this to prevalence of trees in public spaces, and controlling for things like income, age, and education, researchers were able to measure the effect of trees on public health.
Results
So, what kind of effect are we talking about? Well, researchers found that “having 10 more trees in a city block, on average, improves health perception in ways comparable to an increase in annual personal income of $10,000 and moving to a neighbourhood with $10,000 higher median income or being 7 years younger.”
The results are even better when it comes to cardio-metabolic conditions (obesity, heart disease, stroke, etc.), with researchers saying that an increase of eleven trees per block was “comparable to an increase in annual personal income of $20,000 and moving to a neighbourhood with $20,000 higher median income or being 1.4 years younger.”
The Takeaway
It’s pretty clear—having trees in your neighbourhood is good for the neighbourhood. Why that’s true is a bit less clear. The study didn’t identify the mechanism that improves health, but it could be down to the fact that trees improve air quality and there’s a proven psychological link between green space and stress reduction.
