Smoke from 180+ Canadian wildfires blankets 20 US states with hazardous air

On Thursday evening, the sky above Chicago turned the color of old smoke. The air quality ranking that night was the worst on the planet—not in Delhi or Beijing or any of the cities usually at the top of such grim lists, but in the American Midwest, where more than 180 active wildfires burning across northern Ontario had sent their smoke drifting southeast in a massive plume. Detroit and Minneapolis followed Chicago in the global rankings. By week's end, millions of Americans across more than twenty states would be breathing air that officials classified as unhealthy, very unhealthy, or hazardous.

The smoke had traveled far. It blanketed Minnesota, where its own wildfires burned, and continued eastward across the Great Lakes region and into the Northeast, reaching all the way to New York. In New York City, the sky took on an orange tint and the air smelled acrid—a smell that residents recognized from 2023, when Canadian wildfire smoke had created what officials now feared might be repeated: the city's most significant smoke event in three years. Governor Kathy Hochul announced that more than 100,000 N95-style masks were being distributed to counties, with additional supplies placed at Penn Station and Grand Central for commuters. The city opened hundreds of cooling centers as heat and smoke converged, both pressing down on the region.

Mayor Zohran Mamdani addressed New Yorkers on Thursday, his message direct: today would be the worst day of the event. He did not soften the warning. At unhealthy air quality levels, he said, everyone—not just those with asthma or heart conditions, not just older adults—everyone might feel health effects. Every New Yorker should take precautions. The city's alert remained in effect until midnight, though forecasters warned that smoky conditions would linger through the evening.

The geographic reach was staggering. Air quality alerts had been issued across 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. In some places, the air had reached hazardous levels—parts of Pennsylvania, Michigan near Detroit, and areas of Ohio, Illinois, Wisconsin, and Minnesota. Officials in those regions told people to stay indoors. In others, the air was very unhealthy: Pennsylvania, New York, Ohio, Michigan, Illinois, Wisconsin, Minnesota, and Indiana. The National Weather Service in Detroit warned that smoke would be densest in the afternoon and evening, with visibility sharply reduced.

Senator Ed Markey of Massachusetts connected the immediate crisis to the larger pattern. The smoke was darkening skies and entering lungs across his state, he said. With a record El Niño forecast for the year, more wildfire smoke days lay ahead. The climate crisis, he added, does not stop at borders. In Washington DC, officials told residents to expect more smoke to move in, bringing with it the smell of a campfire and reduced visibility. In Virginia, forecasters warned of additional waves of Ontario smoke pushing south through Friday, creating hazy conditions. In Indiana, weather officials noted that the Great Lakes region currently had some of the worst air quality in the world.

Not everyone faced equal risk. New York officials specifically cautioned elderly people, pregnant women, and those with heart or lung disease to remain inside. The vulnerable were most vulnerable. Yet the mayor's warning had been broader: at these levels, the harm was not confined to the already sick or the already old. It touched everyone.

Relief might come Saturday, when rain was forecast. But officials were monitoring closely for any deterioration in conditions. The World Cup final was scheduled for Sunday in New Jersey—a highly anticipated event now shadowed by the question of what the air would be like. The immediate crisis might pass. But the pattern, officials suggested, would not. More smoke days were coming, carried on winds from fires that would keep burning as long as the conditions that fed them persisted.