Researchers from Simon Fraser University and the University of British Columbia looked at nearly 1,500 public elementary schools in Canada's 10 largest cities: Vancouver, Calgary, Edmonton, Winnipeg, Toronto, Hamilton, Mississauga, Ont., Ottawa, Montreal and Quebec City.
Addresses were geocoded with the proximity to the nearest major road calculated for each school. Researchers gathered data on income and neighbourhood characteristics from the 2006 census.
Studies of children who live near major roads have found that traffic-related air pollution is associated with lower lung function, impaired lung growth, asthma, ear infections, and lower cognitive functioning, said SFU geography graduate student Ofer Amram. He co-authored the study with SFU health sciences assistant professor Ryan Allen and three UBC colleagues.
Amram said similar studies of traffic-related noise have found links to increased blood pressure, reduced sleep quality and cognitive deficits.
Research also reveals that when children are exposed to higher air pollution and noise at school it can lead to poorer average academic performance, he noted.
Based on measurements of nitrogen oxide concentrations, ultrafine particle counts, and noise levels in Vancouver, Edmonton and Winnipeg, researchers defined schools located less than 75 metres from major roads as their zone of primary interest.
Across the country's 10 biggest cities, 16.3 per cent of public elementary schools were located with 75 metres of a major road, with a wide variability between cities.
Montreal had the highest percentage of public schools located near a major road at 33 per cent, while Mississauga had the lowest at three per cent, Amram said.
Researchers found schools located in neighbourhoods with a higher median income were less likely to be near major roads. Meanwhile, those housed in more densely populated neighbourhoods were more frequently close to major roads.
Amram said the study looked at overall patterns across Canadian cities and said the relationship of closer road proximity for schools in poorer neighbourhoods was pretty consistent across the cities they investigated.
"There were other studies in the U.S. that showed the same thing, and we weren't sure what to expect here in Canada, so we were sort of a little bit surprised by that," he said Thursday from Burnaby, B.C.
Amram noted that the results don't necessarily describe the situation at every individual school, but rather the general relationship between proximity and neighbourhood income.
"I cannot talk about what's happening in higher-income neighbourhoods or lower-income neighbourhoods, but this is the trend that we see," Amram said. "In most of the cities in Canada we see that — it's not apparent in one specific city."
For existing schools, Amram said improvements could entail constructing sound barriers or installing filtration systems to help improve air quality. For those yet to be built, Amram said it boils down to planning.
In addition to locating schools farther from major roads, he said another consideration could perhaps be establishing legislation, which was done in California. The state enacted legislation in 2003 limiting the placement of new school sites close to busy traffic corridors or freeways.
Amram acknowledges it still may be a challenge logistically for all schools to be housed away from major roads, but said modifications are possible.
"You could put the classrooms kind of farther away or the playground farther away within the school property. I'm sure there's a way around it," he said.
"It's something to think about when you build a school."