‘The caveat is that off to the west of us, we’re seeing fires in the Elk and Slocan Valleys and west of Kamloops and it would take a slight change in the wind and we could be under a plume’
A dense haze that settled over Calgary Wednesday is a spike in wildfire smoke levels that should soon moderate, said an Environment and Climate Change Canada meteorologist.
But Brian Proctor said that situation remains fluid with the eruption of more fires in eastern B.C. that could bring more of the toxic clouds over the city.
“(Wednesday) will be the worst and in a little while, on Thursday, it’ll come down to moderate,” he said.
“But the caveat is that off to the west of us, we’re seeing fires in the Elk and Slocan Valleys and west of Kamloops and it would take a slight change in the wind and we could be under a plume.”
But temperatures tumbling from the 30 C-range to the low 20s on Thursday should bring some comfort for Calgarians who might have been reluctant to cool their homes by opening windows, he said.
“It’s going to feel so much better for us Thursday with less widespread smoke,” said Proctor.
The haze blanketing Calgary comes from wildfires circulating throughout the prairies along with smoke from fires in B.C. and the U.S. Pacific Northwest, he said.
Wildfire smoke toxic
Levels of particulate matter (PM) 2.5 in Calgary Thursday — around 85 micrograms per cubic metre — isn’t spectacularly high but is still unhealthy, said Mandeep Dhaliwal, air quality program manager with the Calgary Region Airshed Zone, which monitors those conditions.
“The (health) guidelines say we should be below 80 when it comes to PM 2.5, there’s no safe level,” said Dhaliwal, an organic chemist.
“It can cause damage not just to seniors and children but to everybody.”
A level considered a health objective — 29 — was exceeded by PM 2.5 levels nearly triple that, he noted.
Because PM 2.5 are so tiny, they can be absorbed through the lungs into the bloodstream, introducing a host of toxic chemicals.
PM 2.5 can be found in other air pollutants, such as those coming from internal combustion engines, he said, but the prevalence and severity of wildfire smoke mean that’s the most concerning source.
“In terms of toxicity, this is the number one priority — we never get to these dangerous numbers with sulfur dioxide,” said Dhaliwal.
“We get these numbers all the time now (with wildfire smoke).”
On its smokiest days, Calgary’s PM 2.5 levels have hit a 25-hour average of 150, with the number spiking during the course of the day to 500.
He recalls one reading taken in a wildfire zone in the Grande Prairie area that exceeded 1,000.
“It was right off the charts,” said Dhaliwal.
Calgary had later start to wildfire smoke season, but ‘we’ve probably got a ways to go yet’
Prior to this bout of wildfire smoke this year, Calgary saw its last more severe encounter with it in May — a far cry from 2023 when the city set a record for smoky hours.
By 8 p.m. the following day, Calgary had seen 477 hours of smoke so far in 2023.
Scientists say that’s largely due to climate change which dries out vegetation, making it easier for wildfires to start and burn more intensely, while also increasing the number of lightning ignitions.
“I’m surprised it took this long to get here (in 2024), I thought it’d be in June or early July,” said Dhaliwal.
Environment Canada’s Proctor also said the start of Calgary’s severe wildfire smoke season this year was late “but as soon as we turned the heat on, there it was.”
He also said last year, the fire season extended into September.
“So we’ve probably got a ways to go yet,” said Proctor.
During high-risk air quality periods, Calgarians are urged to stay indoors and not perform strenuous outdoor activities.