Jun 29, 2023 - Science

Canada wildfire season declared worst on record

Buildings as smoke from northeastern Ontario and central western Quebec wildfires creates haze in Toronto, Ontario on June 28, 2023. Environment Canada issued air quality warnings for the Northwest Territories and huge areas of the heavily-populated provinces of Ontario and Quebec.

Smoke from northeastern Ontario and central western Quebec wildfires creates a haze across the skyline in Toronto, Ontario, on Wednesday. Photo: Mert Alper Dervis/Anadolu Agency via Getty Images

Firefighters in Canada are now battling 497 active wildfires across the country after 31 new blazes ignited, according to the latest data from the Canadian Interagency Forest Fire Centre.

The big picture: New figures show 3,023 fires have burned across some 19.7 million acres of land during what officials this week declared has been Canada's worst wildfire season on record.

  • Smoke from the fires has triggered multiple air quality alerts in Canada and across the U.S. since the country's worst-ever fire season began in April.
  • Chicago, D.C., and Detroit were among the latest cities to endure some of the world's worst air quality on Thursday morning.

Threat level: Inhaling high concentrations of wildfire smoke at ground level can cause serious health complications and is particularly dangerous for elderly populations and those with heart ailments or asthma.

Context: Multiple studies show human-caused climate change is a key driver behind increased wildfire risk and that heat waves are more likely to occur, be more intense and last longer due to this.

Go deeper: Canada's wildfire smoke emissions break records

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