Smoke from forest fires in Canada, it swept up the East Coast, obscuring cities in hazy smog and putting about 100 million people under an air quality warning. More than 400 fires are burning in British Columbia, Alberta, Quebec and Ontario, and half are out of control. New York has become home to the worst air quality in the world. Philadelphia also issued a red alert, advising people to stay indoors, and plumes could continue to pelt the region for several more days, with smoke stretching across Washington, DC, to Atlanta, Georgia.
In the United States, wildfires that started under pressure once seemed to be a problem unique to the West Coast, like the 2018 camp fire that destroyed the California town of Paradise. A variety of factors contributed to that massive fire, including the region’s legacy of firefighting, which allowed dead brush to pile up. Climate change means that higher temperatures are drying up and burning catastrophically. This is currently a problem in Canada as well. The number of fires for this time of year is up only slightly above average, but “fire size and fire intensity are up significantly,” says Mike Flannigan, a professor of wildland fires at Thompson Rivers University in British Columbia. .
In other words: East Coast, welcome to the Pyrocene, or Age of Flame, as fire historian Stephen Pyne calls it. Climate change and human interference with the landscape have combined to make wildfires bigger and more intense, big enough to send plumes of toxic smoke not only from Canada up the East Coast, but across continents. “Climate change acts as a performance enhancer: it worsens what is a natural rhythm,” says Pyne. “There is no reason to think that 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 wildfire smoke exposure can be devastating for vulnerable people, but less is known about the long-term effects of short-term exposure. “This is relatively new, to have this kind of mass exposure to a group that has never been exposed before,” she says.
Wildfire smoke is a complex amalgamation of materials, including burnt plant material and — if buildings are ablaze — man-made things like plastic. What makes smoke visible are its toxic particles – called PM 2.5 and 10, meaning particles smaller than 2.5 and 10 microns. But there are also a lot of invisible nasties, like benzene, formaldehyde, carbon gases, and even fungal pathogens. As smoke travels through the atmosphere, it can actually form new chemical hazards over time, such as ozone, which worsens 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 airplanes through wildfire smoke to study its components. “But there are a lot of things that are left out that are on the EPA’s list of hazardous chemicals.”
Forest fire smoke can cause immediate health effects, such as heart attacks, strokes and bronchitis, especially in more vulnerable people with respiratory problems, and can be dangerous for pregnant women. “These single exposure events can be really devastating for people with pre-existing conditions,” says Shahir Masri, an air pollution scientist at the University of California, 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 an increase in air pollution with fine particulate matter from wildfire smoke. “Whether it’s Covid or any other virus, this is the time to avoid not only exposure to the fine outdoors, 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 become a record, says Flannigan. Hundreds of wildfires have burned across Canada – some for days or weeks – usually started by human activity or lightning, then fueled by dry vegetation and exacerbated by hot, dry and windy weather. Warm air rising over land has lifted that smoke to altitudes between 5,000 feet and 20,000 feet, where the haze is quickly carried south and east by strong winds.
