[URBAN NOTE] On how Torontonians (and other humans) benefit from trees

[rfmcdonald]

A post on Discover magazine's Inkfish blog alerted me to some interesting research.

What’s a tree worth to you? According to a large study in Toronto, trees may increase both how healthy you feel and how healthy you really are. Having some extra foliage on your block could be as good for your health as a pay raise–or an anti-aging machine.

It’s a complicated relationship to figure out, because variables that affect how many trees you see each day could also affect your health. The population of a concrete, inner-city apartment complex may have socioeconomic differences, for example, from the population of a leafy, well-tended suburb. University of Chicago psychologist Marc Berman and his colleagues used a detailed analysis to try to tease out the impact of trees themselves.

They started by going to Canada. In a country with universal health care, they figured, access to doctors isn’t as much of a variable as in the United States. Since socioeconomic status can still affect how people use doctors, the authors also gathered information on their subjects’ income and education. And rather than comparing people from multiple areas, they focused only on the city of Toronto.

From a large-scale, ongoing project called the Ontario Health Study, the authors collected data on over 31,000 adult residents of Toronto. In addition to household income and years of education, they looked at subjects’ sex, diet (self-reported servings of fruits and vegetables per day), and neighborhood. The Ontario Health Study questionnaires also asked subjects whether they’d ever been diagnosed with various physical and mental health conditions.

The final measurement was health perception: how healthy do subjects feel they are, on a scale from 1 to 5? It sounds vague, but this measurement has been found to strongly predict actual health, the authors write.

The Toronto Star's Geoffrey Vendeville went into more detail.

Using data from Toronto, a team of researchers has found that having 10 more trees on your block has self-reported health benefits akin to a $10,000 salary raise or moving to a neighbourhood with a $10,000 higher median income or being seven years younger.

By comparing satellite imagery of Toronto, an inventory of trees on public land and general health surveys, the team, led by University of Chicago psychologist Marc Berman, found that people who live on a tree-lined block are less likely to report conditions such as high blood pressure, obesity, heart disease or diabetes.

Their findings appeared last week in the open-access journal Scientific Reports.

The study suggests “pretty strongly” that planting 4 per cent more trees would have significant health benefits, Berman said.

Researchers don’t know why, exactly, trees seem to be good for people’s health.

“Is it that the trees are cleaning the air? Is it that the trees are encouraging people to go outside and exercise more? Or is it their esthetic beauty? We need to understand that,” he said.