Canadian wildfire smoke continues to shroud large parts of the United States, affecting approximately 109 million people across the midwest, mid-Atlantic and north-east on Friday. Cities including Chicago and Detroit experienced hazardous air quality, with the Air Quality Index reaching 361, according to the government website AirNow. Residents were advised to stay indoors and reduce activity levels.
Smoke spreads to major cities
The smoke drifted into Baltimore and Washington DC overnight, creating very unhealthy air quality with index values of 281 and 247, respectively, as of 6am eastern time. In New York City, where smoke has blanketed the city since Tuesday, air quality stood at an “unhealthy” 184 early Friday, later improving to 124, considered “Unhealthy for Sensitive Groups”. Philadelphia and Cleveland had readings at about 260, classified as “very unhealthy”. Other parts of Michigan, Minnesota and Wisconsin also recorded readings in the “hazardous” range.
Global pollution comparisons
The global air quality index showed pollution in five major North American cities at higher levels than Kinshasa or Nairobi in Africa, the next cities on the list. Nasa’s Fire Information for Resource Management System (Firms) indicates pockets of Canadian wildfires reaching deep into the Northwest Territories.
In Michigan, the state’s department of environment, Great Lakes and energy recommended closing windows, minimizing door openings, and using HVAC systems rated Merv-13 or higher. The alert stated: “If you must be outdoors for short periods of time, an N95 or P100 respirator marked with NIOSH is recommended.”
Relief expected in some areas
Some cities in the north-east and New England are expected to get relief from smoky skies on Friday as stronger winds from Quebec – not from the wildfire zone in western Ontario – blow the smoke out. Mark Parrington, senior scientist at the Copernicus Atmosphere Monitoring Service, said: “There has been a clear intensification in wildfire activity for Canada over the past few weeks. Smoke from major fires – particularly in Ontario – [is] already having severe air quality impacts across cities in the Great Lakes region and the north-eastern United States.”
“Our forecasts show the smoke continuing to move eastwards across the North Atlantic, and potentially towards Europe, highlighting the scale of wildfire pollution and how it can travel thousands of kilometers across borders and impact air quality in places far beyond the fires themselves,” he added.
Impact on events and weather
Organizers of the World Cup final in East Rutherford, New Jersey, are monitoring smoke patterns carefully. Smoke currently over the mid-Atlantic is expected to blow back up into the north-east. An approaching storm system from the west, bringing severe thunderstorms, could interact with the smoke, creating worse conditions as rain drags smoky air from higher in the atmosphere down to the ground. When that storm passes late on Saturday, air quality is likely to improve in time for a 3pm Sunday kick-off. Authorities have said they are “monitoring” whether smoke plumes will affect the game, sources familiar with the situation told ABC News.
Scale of Canadian wildfires
Canada’s largest fire, near Ontario’s remote Wabakimi provincial park, is reported to be spread across 787,802 acres (318,812 hectares) by the Canadian Interagency Forest Fire Center. It is among 194 out-of-control and large fires that were burning as of Thursday. Parrington said smoke plumes from the large-scale wildfires in Canada’s Northwest Territories had reached the Arctic Ocean as well as across other parts of the country. Nearly 6 million acres are estimated to have burned, less than a quarter of land consumed by blazes when Canadian wildfire smoke last blanketed the US in 2023. Fires in northern Minnesota have burned more than 63,000 acres. In the west, wildfires in Oregon, Washington and Idaho have also been reported.
Health and economic costs
Smoke plumes from wildfires risk reversing gains made from reductions in other pollution sources, according to a 2025 study by Carnegie Mellon University’s Tepper School of Business. Researchers estimated that smoke from wildfires and prescribed burns caused $200 billion in health damages in 2017, and were associated with 20,000 premature deaths. Co-author Nicholas Muller, professor of economics, engineering, and public policy, said: “Many studies have found that fire smoke, like other air pollutants, is associated with increased morbidity and mortality risk.”
Extreme rainfall in Texas
At the other end of the US, heavy rainfall across south and central Texas, including Texas Hill Country, an area hit by catastrophic flash flooding last year, has exceeded 20 inches in some places since Monday. The Guadalupe River near Comfort in Kerr county crested at 37 feet above flood stage. AccuWeather’s Global Weather Center put a preliminary estimate of damage and economic loss at $11 billion to $13 billion. The extreme rainfall is consistent with findings from the company’s climate research unit that has found rainfall in amounts greater than 4 inches in a 24-hour period has increased by 70% since 1995.
AccuWeather’s chief meteorologist, Jonathan Porter, said in an email: “In a warming climate, those historical probabilities are changing, meaning these extreme rainfall events can occur more frequently than the statistics from the past would suggest.”
