OTTAWA — Air pollution from wildfires remained well above healthy levels across much of southern and northern Ontario and several communities in British Columbia and Alberta on Thursday.
There may be some hope on the horizon after the number of fires burning across the country fell slightly, but forecasts suggest smoke warnings will remain in place in several provinces into the weekend.
Meanwhile, hot temperatures and high winds forced the evacuation of Edson, a town of about 8,400 in northwest Alberta, after a fire jumped a fire guard and threatened the community.
"All things considered, so far so good," said town mayor Kevin Zahara. "But the next 72 hours are going to be critical for us."
The record-setting air pollution that blanketed Ottawa and much of eastern Ontario with a yellow-tinged haze Wednesday had mostly cleared by Thursday morning, and the sun was even glimpsed briefly.
But further south, towards the Greater Toronto Area and in areas around Sudbury and North Bay, the air quality remained poor. Environment Canada forecast very high-risk air quality in the GTA, southwestern Ontario and the Niagara region into Thursday night.
Multiple health studies have linked wildfire smoke to serious health consequences including heart attacks, strokes and breathing problems, and the poor air quality has prompted cancellations or changes to outdoor activities as a result.
The Toronto District School Board joined several of its counterparts across the region in cancelling outdoor activities and moving recess inside for a second straight day Thursday. The Toronto Zoo also announced it would close early.
On Friday and Saturday, most of Ontario should expect moderately bad air quality. At high risk, people are advised to reduce their outdoor activities, while at moderate risk the advice is to only consider doing so.
In British Columbia there was a risk of moderately bad air quality in parts of the Fraser Valley, Vancouver and some parts of Vancouver Island on Thursday. By Friday, the risk is expected to be low almost everywhere in the province but Fort St. John.
In Alberta, the worst air is near Fort Chipewyan, which remains on an evacuation order as a fire burns out of control. Wood Buffalo and Grande Prairie also have high risk air quality forecasts.
Moderately bad air quality is forecast for Edmonton and Calgary on Friday.
The Canadian Interagency Forest Fire Centre said there were 431 fires burning on Thursday in nine provinces and two territories. That was down from 441 Wednesday, with Quebec extinguishing 10 fires since Wednesday morning.
The number of out-of-control fires also fell from 256 on Wednesday to 234 on Thursday, including a change in status for more than a dozen fires in Quebec.
The week's events prompted the second debate in the House of Commons related to climate change and fires this week Thursday, this time on a Bloc Québécois motion.
Many MPs took time to express solidarity with Canadians affected by the fires and smoke, and the firefighters taking great risks to battle them, even as they also pointed fingers at each other over inaction.
The Bloc and NDP accused the Liberals of claiming to be acting on climate while still subsidizing and approving the expansion of fossil-fuel projects. The Liberals blamed the Conservatives for pushing back on climate policies such as carbon pricing without offering any alternatives.
"Climate change is real and we are seeing and living its impact every day," Environment Minister Steven Guilbeault said.
This, he said, is the worst fire season Canada has ever experienced and it has had devastating consequences.
"People have lost everything," he said.
More than 43,000 square kilometres have burned so far this year, 15 times the average amount normally burned by the second week of June.
In 1995, 71,000 square kilometres burned, the most ever in a single year. The pace of burning at the moment has Canada on track to surpass that 1995 total before the end of June.
Mohammad Reza Alizadeh, a climate environmental researcher at the Massachusetts Institute of Technology, is studying climate extremes including wildfires, heat waves and droughts. Alizadeh, who did his PhD at McGill University in Montreal, said in an interview this spring's unusually severe fire season in Canada is "really a clear sign of climate change."
Fires, said Alizadeh, love three things: dry fuel, windy hot weather and frequent lightning strikes. Climate change is bringing all three, he said.
The result is that when a fire starts, it can explode out of control very quickly.
"Global warming has a direct and obvious effect by raising temperatures, which dries out the vegetation more quickly," he said.
"More fires then start and they burn further. It only takes a few hot days to cause bad fire conditions, even when there have been recent heavy rainfalls."
There was evidence of that in Quebec, which in May saw only limited fire activity, but in the first week of June more than 230 fires started, burning 6,700 square kilometres. Those fires followed several days of temperatures above 30 C the last week of May, which came after a lengthy period of lower-than-usual precipitation.
Part of the debate in the House of Commons Thursday centred around the cause of the fires. The Canadian Interagency Forest Fire Centre database says about half the 2,363 fires in 2023 so far were started by people, which could mean ignition sources from campfires and fireworks to cigarette butts or even backfiring vehicles.
About one-third were started by lightning strikes, while the rest have no known cause yet.
Alizadeh says climate change is causing more lightning strikes, but still plays a role if a human ignites a fire, because dry vegetation will burn much faster and be more susceptible to a small spark.
He also said climate change affects the smoke effect, with hot windy weather and low pressure systems helping the smoke drift further and sit for longer in one spot.
This report by The Canadian Press was first published June 8, 2023.
Mia Rabson, The Canadian Press
Note to readers: This is a corrected story. An earlier version said 2014 was the worst year on record for fires in Canada.