Fall Leaves

Trees Grow Healthier Communities

The nature of trees offer surprising health benefits in our most populated areas.


I took a meditation course years ago and, during one session, we went to a downtown Toronto park (Queen’s Park), chose a tree to sit under, stare up at, and just breathe. I have to say, taking in the fluttering leaves, with the sunshine intermittently peeking through, was such a calming, surreal experience that I don’t know why I don’t do it more. People walking by looked up into the tree to see what I was looking at so intently. They probably wanted to join me in my bliss. There’s just something about trees… and it’s not just in my head.

Toronto residents living in areas with more trees reported feeling healthier and having fewer heart-related health issues, such as obesity, heart disease, and diabetes. Omid Kardan and Marc Berman from the University of Chicago, along with researchers from Canada, the US, and Australia, noted that these effects didn’t depend on a person’s age, income, or education. Having 10 more trees in a city block had the same effect on health perception as earning $10,200 more per year or being 7 years younger.

Canada has a universal health care system, so the researchers admitted that in countries without one, economic status could have an effect on a person’s health perception. However, studies of US residents, a country without universal health care, showed similar results.

Kristen Malecki, from the University of Wisconsin-Madison, showed that Madison residents had lower anxiety, depression, and stress associated with higher levels of green space. This decrease in symptoms was similar to that seen for other factors affecting mental health, such as income and insurance status.

A group at Portland State University found decreased levels of nitrogen dioxide in the summer months associated with larger amounts of trees at various measurement sites in Portland. They estimated that decreased NO2 associated with the city’s trees could result in a significant reduction in respiratory problems, including asthma.

Cleaner air seems like an obvious link between trees and physical health. But the link between the mere presence of trees with mental health and well-being is still not known. It may be that tree-lined streets encourage people to get outside and be more physically active, making them fitter and happier. Or healthier people may choose to live in greener neighborhoods.

And for me I wonder, sitting under that tree years ago, was my contentment caused by the cleaner air I was breathing, or was it the green leafiness and sunshine, the sound of leaves rustling in the wind, the cool shade, or a combination? I don’t know, but it’s something I should do more of.

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Susan Bustos is a freelance science writer and editor who sometimes dabbles in arts and crafts in the name of science communication. She has written and talked about the parallels of knitting and protein synthesis, and turned a child’s play kitchen into a play lab. She completed her PhD in biochemistry from the University of Toronto, followed by a postdoctoral fellowship at the Structural Genomics Consortium. She is interested in career development of scientists and has produced a video series showing the diverse career paths scientists can take.