Smoke from intense wildfires darkened what were supposed to be bright summer skies for millions in the United States and Canada this month. People had to don masks to venture outdoors to avoid feeling sick from the overwhelming smell and smog.
Though some smoke has cleared, there are currently 877 active wildfires in Canada, and about 109 million people have been affected over the course of July across the Midwest, mid-Atlantic and Northeast. Fires ignited in several states this month, including Minnesota, Oregon and Washington. In Ontario, Canada, evacuation orders are still in effect.
The dramatic smoke events from worsening wildfires are fueling a new public health challenge for America’s young people. They’re eroding progress that had been made toward improving air quality for future generations, and putting children at risk of both the physical and emotional harms of a smokier, ember-filled world.
Several decades ago, air across North America was visibly contaminated. Iconic photos of city skylines from the 1960s and 1970s showed ominous skies over major urban centers like NYC. This changed after the Clean Air Act, a landmark environmental law passed in 1970, beginning a major effort to reduce pollution. Levels of the six major pollutants it targeted dropped by over 40 percent in the first few decades after its passage. This progress continued, and levels of PM2.5 — tiny, inhalable air pollutant particles formed through combustion — dropped 42 percent between 2000 and 2022.
But in recent years, such gains have been undermined by wildfires. A study released in 2023 determined that wildfires have eroded roughly 25 percent of progress made in reducing PM2.5 pollution in nearly three-fourths of U.S. states. In some states like California and Washington, the pollution from wildfires has been so great since 2016, that about half of the air quality gains made since 2000 were erased.
There are multiple reasons wildfires have been getting worse. The growing severity, but not extent, of wildfires can be attributed to climate change: Hotter temperatures cause plants to dry out, making forested areas more likely to ignite and burn longer, said Kelvin Fong, an environmental health scientist. Extreme heat conditions are up to five times more likely because of global warming, according to a report from Climate Central. This was on display recently, when a heat wave engulfed large portions of the U.S. the same week that air quality dropped alarmingly because of fires. Countries across the pond like France and Spain are also battling a summer of heat waves and dangerous blazes.
Forest management practices have also contributed to worsening fires in some places. In the late 1800s, the U.S. adopted what would become a nearly century-long policy of fire suppression. Putting out fires as soon as they started reduced the amount of forest burned, but led to a buildup of flammable brush on forest floors. The U.S. has been shifting away from this practice in recent decades — though, amidst this year’s fires, President Donald Trump’s administration decided to focus on “full suppression” once more. The Canadian wildfires have less to do with forest management gone wrong: They are primarily burning in forests that were never managed in the first place.
As smoke drifted south from Canada over the last month, some parents felt nervous about taking their children outdoors. Robert Vargas took his nine-year-old son to a park in the Bronx, where he told The New York Times, “I’m worried it could mess up his lungs.”
There’s legitimate cause for concern. Large fires create wildfire-specific PM2.5, which may even be about ten times more harmful to children’s respiratory health than PM2.5 from other sources, according to a report from UNICEF.
During wildfire smoke events, emergency room visits for asthma and other respiratory issues increase dramatically. The Canadian wildfires in 2023 prompted a nearly 20 percent increase in emergency room visits for asthma in the U.S., where about 4.9 million children have the chronic disease.
The effects of wildfire smoke on young people extend beyond the lungs. Pregnant women exposed to wildfire smoke are more likely to experience preterm births and lower birth weights, which is associated with health concerns for those babies, like higher risk of infection and trouble gaining weight.
Long-term brain health is also strained by extreme smoke events. Jennifer Richmond-Bryant, an associate professor at North Carolina State University said that, “There is a growing body of evidence that PM2.5 exposure can have neurological impacts, including reductions in cognitive development.” One 2024 study published in the journal Environmental for instance, found that exposure to air pollution — including PM2.5 — during early childhood development decreases cognitive performance. A study the next year in Environmental Research found it alters brain structure.
While long-term studies tracking children’s health outcomes after wildfire smoke exposure are slim, Fong said, “It is very likely that those exposed to prolonged or extremely high levels suffer irreversible damage.” And much like wildfire smoke is not confined to one area, the impact goes beyond physical health. “We also have to think about those who are in [the] immediate vicinity of the wildfires and have to evacuate with immediate threats to their housing insecurity, leading to physical and mental health impacts,” Fong added.
Communities have seen this before. After a 2016 wildfire in Alberta, Canada, which was referred to as “The Beast,” 37 percent of area students aged 11 to 19 were diagnosed with probable PTSD more than a year after the event. This is over double the national average. Parents with children who lived through the destructive 2025 fires in Los Angeles also reported high levels of stress after being displaced from their homes. Some found outlets for their stress like sports, but many will likely feel the stress for years to come.
Eyewitness accounts of the Canadian and U.S. fires this month showed the terror of teens who experienced them up close. “It was one of the most scary things I think I’ve ever seen,” Ontario teen Miiyah Paavola told CBC News. “Evacuations like that have never happened … I never had to leave in an emergency like that.” Several teens recounted narrowly escaping the fires in the Namaygoosisagagun First Nation in Ontario by boat. One told CBC News, “The smoke, you can just feel it in my lungs. It’s so hot.”
