Trees stretching their canopies over city streets and grass tickling the sidewalk near your home are more than just pretty, they could actually be helping you live longer, a new study suggests.
Researchers at the University of New Brunswick used census and tax data to track 1.3 million non-immigrant Canadian adults living in the 30 biggest cities across the country, from Victoria to St. John's, over 11 years starting in 2001. They measured the amount of greenery from trees, shrubs, grass and other plants within 250 metres (about two blocks) of the study subjects' homes, using postal codes and satellite data. And they found that as the amount of greenery increased, people's risk of premature death decreased "significantly" from natural causes.
"There was a lot bigger effect than I think any of us had been expecting," said Dan Crouse, a health geographer and lead author of the study published this week in the journal The Lancet Planetary Health.
Using NASA's Aqua satellite, the greenery was measured on a scale of 0 to 1. (Zero represented bare ground; 1 was complete coverage by dark green leafy plants.) The study found that each 0.15-point increase in greenness near the subjects' homes was associated with an eight to 12 per cent decrease in the risk of death over the course of the study.
Crouse said the link between greenness and lower death rates remained even after researchers accounted for the effects of air pollution.
While previous studies have shown that exposure to green space and parks can improve mental health and in some cases physical health, the researchers say this is the first big study to show a clear link between green surroundings and a lower risk of premature death.
It also suggests that green spaces don't have to be actual parks in order to have health benefits.
"What we're able to show with this study is really just having trees around where people are living is really important," Crouse said.
The study found that the positive effect of green surroundings was greater for people in middle age than in other age groups.