Air Quality in Toronto Is Among the Worst in the World

Toronto has several distinctions. It is Canada’s largest city and its financial center. It hosts the Toronto Raptors, which won the N.B.A. championship in 2019. And it is the birthplace of the hip-hop megastar Drake.

On Wednesday, the city gained another, less celebratory distinction: It had among the worst air quality in the world for a time, according to IQAir, a Swiss air quality technology company, as smoke from wildfires in northeastern Ontario and Quebec billowed into the area, turning the air hazy and acrid.

Environment Canada warned on Thursday that poor air quality in the Toronto area would likely last into Friday. “Wildfire smoke can be harmful to everyone’s health even at low concentrations,” it said in a statement. “People with lung disease (such as asthma) or heart disease, older adults, children, pregnant people, and people who work outdoors are at higher risk of experiencing health effects caused by wildfire smoke.’

The poor air quality is forcing some changes to daily life. Some residents were postponing their daily runs or venturing outside wearing N95 masks. Outdoor activities at some city-run day care centers this week were put on hold.

The Toronto Jazz Festival, a gathering known for its music-fueled outdoor revelry, wrote on its Facebook page that it was canceling outdoor programming on Wednesday “to ensure the safety of our guests, artists, crew and volunteers.” Outdoor events were set to resume on Thursday.

Canada has been experiencing its worst wildfire season in decades with fires burning from British Columbia on the west coast to Nova Scotia on the other side of the country, forcing tens of thousands of people to flee their homes.

Climate research suggests that heat and drought associated with global warming are major reasons for the increase in the bigger and stronger fires.

As fire updates have become a daily occurrence on national television news broadcasts, the blazes have also helped unite a vast and sometimes polarized nation, with volunteers, firefighters and army reservists from other provinces rushing in to lend a hand. Firefighters from abroad have also come to help, including from the United States, Mexico, Spain, South Africa and France.