Calgary’s worst air pollution moves with the seasons: U of C study



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The city’s south is bearing a larger burden of Calgary’s air pollution during the winter, states an environmental quality study.

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But that status flips during the summer, when the worst effects of the mostly vehicle-produced pollution settle on northeast Calgary, according to a University of Calgary survey.

That comes as a surprise to many, said a man behind the study, Rizwan Shahid.

“People think it’s the same across the city — it’s not . . . Alberta Health Services and other organizations did not consider this varying over space,” said Shahid, an adjunct assistant professor of geography with the U of C.

“There are different mappings and they say this over and over again.”

The reason for the results, culled by researchers with the U of C’s O’Brien Institute for Public Health from a network of air-quality monitors and city data, isn’t entirely clear, said Shahid.

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But prevailing wind directions, topography and the amount of heating during winter could be factors.

Air traffic exhaust and industrial emissions could affect numbers in the northeast, he added.

But he emphasized there’s no need for alarm, given the high-end readings in both winter and summer are at an air quality of four, which is considered on the low side of the moderate health risk according to an Environment Canada index.

“There’s no need to panic, the overall air quality in the city is not bad, there are a few pockets that are bad but even those aren’t so much,” he said, adding readings are typically higher in Canada’s larger cities.

Last summer, smoke from B.C.’s wildfires occasionally drove the index in Calgary to more dangerous levels.

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Maps compare air quality in Calgary during winter and summer.
Maps compare air quality in Calgary during winter and summer. Photo by University of Calgary

Not surprisingly, he said, readings tend to spike alongside major transportation corridors such as Deerfoot Trail and Crowchild Trail.

But Shahid said there are some concerns about the effect even moderate levels of pollution, particularly nitrous oxide and fine particulate matter, can have on cardio-respiratory systems.

Of particular concern are the possible effects of direct exhaust on smaller schoolchildren, he said.

“Idling school buses’ exhaust pipes are at the same height of children, so if they even just walk on the other side of the road from the bus it makes a huge difference,” said Shahid.

For the general public, avoiding walking or jogging along main roads by taking pathways is another way of reducing exposure, he said, noting the maps also chart the more walkable parts of the city.

A study released last year by the International Institute for Sustainable Development pegged the number of premature deaths in Canada caused by air pollution in 2015 at 7,700, with a total cost to society of $36 billion.

Shahid said it’s not known how many of those deaths Calgary accounts for.

“It’s one of the future directions of our study, linking it with a number of health factors,” he said.

The provincial government says it hopes to reduce the health effects of air pollution by phasing out coal-fired power generation by 2030.

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on Twitter: @BillKaufmannjrn


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