Wildfire smoke from Canada and the Western United States stretched across the continent this week, covering skies in a thick haze and triggering health alerts from Toronto to Philadelphia. Air quality remained in the unhealthy range across much of the East Coast on Wednesday morning as the haze pushed southward.
In recent weeks, 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.
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.
“A lot of the masks people have been wearing for Covid are designed to capture PM2.5,” said Dr. Róisín Commane, an atmospheric scientist at Columbia University, referring to N95-style masks. “That’s the right size to be very useful for air quality.”