Smoke from more than 180 active wildfires burning in northern Ontario has triggered air quality alerts across more than 20 states, affecting millions of Americans. Chicago experienced the worst air quality in the world on Thursday evening, according to IQAir's global rankings, followed by Detroit and Minneapolis.
The smoke has drifted southeast from Canada across the US Midwest and Northeast, creating hazy skies from Minnesota to New York. NASA reported that winds carried the Ontario smoke "primarily south-east over much of the southern part of the province, as well as parts of Quebec and the US midwest and north-east, tinting the sky shades of gray and yellow and the sun orange in many areas."
Air quality alerts have been issued for North Carolina, Minnesota, Vermont, Connecticut, New York, Massachusetts, Rhode Island, New Jersey, New Hampshire, Pennsylvania, Illinois, Indiana, Ohio, Delaware, West Virginia, Colorado, Virginia, Maryland, Washington DC, Michigan and Wisconsin. According to the US Environmental Protection Agency, air quality reached "hazardous" levels in parts of Pennsylvania, Michigan, Ohio, Illinois, Wisconsin and Minnesota on Thursday, with officials urging residents to stay indoors.
Health officials are advising residents to limit outdoor activities and remain inside when possible. Vulnerable populations face particular risks, including children, elderly people, pregnant women, and those with heart or lung disease. New York City Mayor Zohran Mamdani cautioned that at unhealthy air levels, "everyone may feel health effects. So today, every New Yorker should take precautions."
The impact on daily life has been significant. In Chicago, beaches and outdoor pools closed as measurements reached dangerous levels. New York Governor Kathy Hochul announced that more than 100,000 N95-style masks were being made available to counties in need, with additional masks distributed at Penn Station and Grand Central. New York officials also opened hundreds of cooling centers to address both the heat emergency and air quality crisis.
New York officials warned this could become the city's "most significant smoke event" since 2023, though they noted current conditions "do not indicate a repeat of 2023's peak levels." They continue monitoring for any deterioration.
Weather forecasters expect smoky conditions to persist through Friday and potentially into the weekend across much of the affected region. Rain is expected Saturday in New York, which could help clear the smoke before Sunday's World Cup final in New Jersey.
Massachusetts Senator Ed Markey emphasized the broader climate implications, stating "The climate crisis is here and it does not stop at our borders." He warned that with record El Niño forecasted for the year, more wildfire smoke days lie ahead.
Residents are encouraged to monitor local air quality reports and follow guidance from public health officials as conditions develop.