Forest fire smoke in Canada engulfed the East Coast, shrouding cities in hazy smog and putting some 100 million people on air quality alerts. More … than 400 fires are burning in British Columbia, Alberta, Quebec and Ontario, and half are uncontrolled. New York City has become home to the the worst air quality in the world. Philadelphia also released a code red alertadvising people to stay indoors, and the plumes could continue to flood the area for several more days ahead, with smoke spreading across Washington, DC, and as far as Atlanta, Georgia.
In the United States, supercharged wildfires once seemed like a problem unique to the West Coast, like the 2018 campfire that wiped out the California town of Paradise. A range of factors contributed to this massive blaze, including the region’s heritage of fire suppression, which allowed dead brush to accumulate. Climate change means warmer temperatures are drying up, causing it to burn catastrophically. This is also the problem in Canada right now. The number of fires is only slightly above average for this time of year, but “the size of the fires and the intensity of the fires have increased significantly,” says Mike Flannigan, professor of wildfires at the ‘Thompson Rivers University in British Columbia.
In other words: East Coast, welcome to the Pyrocene, or the Age of Flames, as fire historian Stephen Pyne calls it. Climate change and human interference in the landscape have combined to make the wildfires bigger and more intense, big enough to send clouds of toxic smoke not just from Canada to the East Coast, but to across entire continents. “Climate change acts as a performance enhancer: it exacerbates what is a natural rhythm,” says Pyne. “There is no reason to think these trends will suddenly stop.”
“It’s a global problem now,” says Mary Prunicki, director of air pollution and health research at Stanford University’s Sean N. Parker Center for Allergy Research. The immediate health effects of exposure to wildfire smoke can be devastating for vulnerable people, but less is known about the long-term effects of short exposure. “It’s relatively new, to have this type of massive exposure to a band that has never been exposed before,” she says.
Smoke from wildfires is a complex mix of materials, including burnt plant matter and, if buildings catch fire, man-made materials like plastic. What makes smoke visible are its toxic particles, called PM 2.5 and 10, that is, particles smaller than 2.5 and 10 microns. But there are also a lot of invisible baddies in there, like benzene, formaldehyde, carbon dioxide, and even fungal pathogens. When smoke travels through the atmosphere, it can actually form new chemical hazards over time, such as ozone, which exacerbates asthma. “The biggest health impacts are definitely from particulate matter,” says Rebecca Hornbrook, an atmospheric chemist at the National Center for Atmospheric Research, who has flown planes through wildfire smoke to study its components. “But there are a lot of things that are omitted that are on the EPA’s list of hazardous chemicals.”
Smoke from wildfires can have immediate health effects, such as heart attacks, strokes and bronchitis, especially in the most vulnerable people with respiratory problems, and can threaten pregnant women. “These single-exposure events can be really devastating for people with pre-existing conditions,” says Shahir Masri, an air pollution scientist at UC Irvine.
Exposure to this type of pollution can also weaken the immune system. A 2021 study found that Covid-19 cases and deaths in California, Oregon and Washington the previous year were exacerbated by increases in fine particulate air pollution from smoke from wildfires. “Whether it’s Covid or any other virus, now is the time to not only avoid exposure to fine outdoor materials, but to really try not to get sick,” says Francesca Dominici, professor of biostatistics, population and data science at Harvard. TH Chan School of Public Health who worked on the study. “Your ability to fight the virus is less effective.”
This year’s fire season in Canada is “unprecedented” and could break records, says Flannigan. Hundreds of fires have been burning across Canada, some for days or weeks, usually started by human activity or lightning, then fueled by dry vegetation and made worse by hot, dry and windy weather. Rising warm air over land lifted this smoke to between 5,000 feet and 20,000 feet high, where the haze is quickly carried south and east by strong winds.
