Canadian Wildfire Smoke Drives Hazardous Air Quality Across US Northeast

Hazardous Air Quality Levels Across the Midwest and Northeast

Smoke originating from wildfires in northern Minnesota and western Ontario has moved into the lower atmosphere, creating unhealthy conditions across a wide swath of the United States. According to reports, the smoke is expected to impact the Midwest, Northeast, and Mid-Atlantic regions from Wednesday to Friday. The wildfire smoke contains microscopic particles of matter known as PM2.5—particles smaller than 2.5 micrometers, or 30 times smaller than the width of a human hair.

The severity of the air quality varies significantly by location. As of Wednesday, more than 100 fires were burning out of control across Canada, with hundreds more being monitored or battled. The smoke has drifted south and east, turning skies hazy from Minnesota to New York. In Toronto, commuters went to work on Wednesday morning under orange skies. The region is also dealing with a heat wave, with temperatures well above 90 degrees Fahrenheit in many areas and an even higher heat index.

On Wednesday evening, New York City’s air quality index (AQI) reached 180, placing it in the “unhealthy” category as defined by the US Environmental Protection Agency. Conditions were even more severe in Duluth, Minnesota, where the AQI surpassed 500—a level labeled “hazardous” and considered unsafe for anyone. Smoky conditions are expected to worsen in parts of the Northeast US on Thursday, including New York.

Health Risks and Protective Measures

The primary concern is the presence of PM2.5, which can trigger or worsen a number of medical conditions, especially in vulnerable populations. Health experts emphasize that even healthy adults should modify their behavior when the AQI goes over 100. Jennifer Stowell, an assistant professor at the University of Maryland’s School of Public Health, stated: “At the very least, it is important to limit your time outdoors to reduce your overall exposure.”

For those who must spend time outside for long periods, Stowell recommends wearing an N95 mask. Stowell, who is currently in Boston, where the AQI hit 110 on Wednesday, noted that she was not planning on attending outdoor events until the evening. Vulnerable populations, including children and the elderly, face heightened risks. Nicholas Nassikas, a pulmonologist and assistant professor of medicine at Harvard Medical School, advises patients with preexisting conditions, like asthma and lung diseases, to limit their time outside. Nassikas noted that children have a faster breathing rate—they just breathe more, while the elderly, who often have compounding conditions and may live in less well-ventilated homes and senior centers, are also at risk.

Climate Change and Long-Term Mortality Concerns

The current smoke event is part of a broader trend of more intense, frequent wildfire seasons. Researchers attribute this escalation to climate change, which is creating hotter and drier conditions that fuel more explosive fires. A study published last year estimated that wildfire smoke already causes 40,000 deaths per year in the US, and could more than double to 70,000 deaths per year by 2050 if warming continues. A similar blast of smoke from Canadian wildfires hit the Northeast in 2023.

Dan Westervelt, an associate professor of climate physics at Columbia University, emphasized the need for caution. I’m going to make sure my kids are staying indoors today, he said. I won’t be doing any physical exertion, like running, today or tomorrow. Regarding the long-term impact of such events, Westervelt added: Exposure to high levels of air pollution over the course of a lifetime or a long period of time is demonstrated numerous times in research to lead to premature mortality. You can chop off some months of your life expectancy if you are living in conditions where you’re very frequently regularly exposed to high levels of air pollution.

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