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Living on tree-lined streets has health benefits, study finds

Using data from Toronto, researchers find having 10 more trees on your block has health benefits akin to $10,000 raise or being seven years younger.
July 13, 2015
By Geoffrey Vendeville

Have you had some work done, dahling, or just moved to a tree-lined street?

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 Bergman, 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, Bergman 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.

The researchers surveyed more than 500,000 trees across the city, focusing on those flanking streets. The study excluded shrubbery and parks.

Faisal Moola, a director at the David Suzuki Foundation and a forest ecology professor at the University of Toronto who was part of the research team, said the results show there are other ways to address some social issues.

“It’s a lot easier to invest in programs to plant trees than it is to raise the median income of everybody in the city,” said Moola.

“This is not to distract that we do have to address systemic issues of poverty and access to health,” he said. “But it does suggest that environmental factors are really important when it comes to the health of local residents as well.”

Toronto is relatively green compared to other Canadian centres, covering 26 to 28 per cent of the city. But they aren’t evenly spread out.

Moola said the tree canopy is lush where he lives in the Beach, but there are fewer trees in poorer neighbourhoods to the east, including Malvern and Kingston-Galloway in Scarborough. Trees are also few and far between in the concrete jungle downtown. They cover only about 5 per cent of the Financial District.

“I would love for the city to look at these results and say, in addition to dealing with all the other systemic issues that have to be looked at, what if we start thinking about reforesting these neighbourhoods.”

Councillor Glenn De Baeremaeker (Scarborough Centre), the city’s tree advocate, hailed the study as a “game-changer.”

“It’s a pretty magical solution, for peanuts.”

It costs the city $72, on average, to buy and plant a tree, a city spokeswoman said. The prices range depending on the size of the trees.

City crews begin planting in April and continue until the ground freezes. They plant about 100,000 trees a year.

Last year, while of the campaign trail, Mayor John Tory pledged to see 3.8 million trees planted over the next decade. The city has planted about 40,000 trees since he was sworn in as mayor in December.

On Earth Day last year, Tory promised to double the city’s tree-planting budget by 2019, from $7 million to $14 million per year.

The University of Chicago study is by no means the first to underline the value of Toronto’s tree canopy.

Last year, TD economists determined that the city’s 10 million trees bring $80 million in environmental benefits and cost savings.

They suck up water, mitigating flooding and soil erosion. They absorb air pollution. And they soften the effects of climate change by storing about a quarter of carbon emissions produced by industry in the city.

“They are the lungs of our city,” said Councillor Sarah Doucette (Parkdale-High Park), who was the city’s previous tree advocate.

“Yes, I’m a tree hugger - and I love it.”