Wildfire smoke from the western United States and Canada raging across the continent, covering eastern skies in a thick smoke and triggering air quality alerts from Toronto to Philadelphia.
In July 2021, a series of near-relentless heat waves and deepening drought linked to climate change have helped to fuel exploding wildfires. In southern Oregon, the Bootleg Fire grew so large and hot that it created its own weather, triggering lightning and releasing enormous amounts of smoke. But more than 80 large fires are currently burning across 13 American states, and many more are active across Canada.
Now, the effects are being felt thousands of miles from the flames.
As the smoke moved eastward across Toronto, New York and Philadelphia on Tuesday, concentrations of dangerous microscopic air pollution known as PM2.5 (because the particles are less than 2.5 microns in diameter) reached highs in the “unhealthy” range for most of the day. Minnesota was heavily blanketed by smoke from wildfires burning across the Canadian border, with the city of Brainerd and others recording “hazardous” levels of pollution, the highest designation of concern from the Environmental Protection Agency.
“What we’re seeing here today is the convergence of several smoke plumes,” said Nancy French, a wildfire scientist at Michigan Technological University, noting that much of the United States was experiencing some amount of haze, even as the highest surface pollution swept across the Midwest and Northeast.
On Tuesday, eerie orange sunsets were coupled with scratchy throats and watering eyes for many people across the two regions.
Fine particulate matter, which is released during wildfires (and also through the burning of fossil fuels), is dangerous to human health. Breathing high concentrations of PM2.5 can increase the risk of asthma attacks, heart attacks and strokes.