Toronto’s air quality ranks among the world’s worst as fires rage in Ontario and Quebec

Known as the Big Smoke, Toronto’s nickname was especially fitting on Tuesday.

As forest fires raged in Quebec and northeastern Ontario, a yellow-tinted smoke settled upon Toronto. By evening, the city’s air quality ranked among the world’s worst, at times ahead of even Lahore, Pakistan, which was labelled the planet’s most polluted city in 2022, according to IQ Air, a global air quality tracker.

Across the GTA, the haze resulted in cancelled recreational sports, postponed school field trips and notices sent to parents that schoolchildren would begin spending recess indoors on Wednesday, including across the York Region District School Board. The Toronto District School Board advised parents late Tuesday that “all strenuous outdoor activities, including athletic events” on Wednesday and Thursday would be rescheduled or moved indoors.

By Tuesday evening, Toronto’s air quality health index (AQHI) had climbed from a level 3 recorded that morning — which is considered “low risk” — to a level 7 out of 10, “high risk” territory. It’s expected to hover at levels 6 and 7 at least through to Thursday.

But it’s unclear when the smoke will dissipate.

“It’s going to get worse before it gets better,” said David Phillips, a senior climatologist with Environment Canada, who’s expecting conditions to worsen Wednesday night as smoke from Quebec and Ontario merge.

It will be hard to immediately recognize when the smoke’s fully gone as its intensity may vary by the hour and location across the city, added Phillips.

“So it is a long bout. It’s not just a one-day wonder,” he continued, adding to expect more of the same this summer as the forecast is calling for drier and warmer weather than usual.“This is like the dress rehearsal.”

Outside of the GTA, wildfire smoke from Ontario and Quebec blanketed large swaths of North America on Tuesday, prompting air quality alerts in multiple American states.

At times, the thick haze hanging over Ottawa nearly obscured the sun. The air quality index reading for the capital city was above a level 10 on Tuesday morning, indicating a “very high risk” to health.

Meanwhile, significant forest fires are currently burning in most provinces and territories. The Canadian Interagency Forest Fire Centre says there are 415 fires currently burning and more than 2,280 fires have burned 37,000 square kilometres so far this year. Wildfires in Quebec and Southeastern Ontario over the weekend caused thousands of people to be evacuated from their homes.

And with summer still two weeks away, Canada is already on pace for its most devastating wildfire season on record, driven in part by climate change delivering conditions conducive to more frequent and severe wildfires.

In a statement to the Star Tuesday evening, Toronto Public Health (TPH) said it had not yet advised the city to cancel events due to the smoke. However, it encouraged recreational organizers to consider the city’s current air quality when deciding whether to proceed with events as those participating in sports breathe more deeply and rapidly.

According to TPH, exposure to air pollutants like wildfire smoke can cause irritated eyes, increased mucus production, coughing and difficulty breathing.

Earlier in the day, Environment Canada and the province had issued a special air quality statement to Torontonians, warning that wildfire smoke could stick around through most of the week.

The statement advised people with medical conditions such as asthma and heart disease, along with children, the elderly, pregnant people and those working outdoors that they were at high risk. (TPH included those with cancer diabetes on their list.) However, the release noted that wildfire smoke is harmful to everyone’s health, even at low concentrations.

Jeff Brook, an associate professor at the University of Toronto’s Dalla Lana School of Public Health and Department of Chemical Engineering and Applied Chemistry, recommended wearing an N95 mask to minimize the smoke’s impacts. But even a standard surgical mask would help, he added.

“Every reduction in breathing this stuff provides a benefit to your health,” Brook said, who also advised people to avoid strenuous activity and close windows and doors.

Despite the haze, Toronto Pearson Airport and Billy Bishop Airport said the smoke had yet to impact their operations as of Tuesday evening. The Rogers Centre opened the stadium’s dome Tuesday but said the decision will be reviewed before each game this week.

Ben Mussett is a Toronto-based general assignment reporter for the Star. Reach him via email: bmussett@thestar.ca