Dangerous smoke from nearly 900 wildfires burning across Canada, with over 200 categorized as out of control, has spread into the United States, impacting air quality for more than 100 million Americans across over a dozen states as of Friday, July 17, 2026.

Air quality alerts extend from the Midwest and Great Lakes to the Northeast and Mid-Atlantic regions, affecting major cities including Chicago, Detroit, Washington, D.C., Philadelphia, and New York City. In New York, wildfire smoke shrouded the sun behind landmarks such as the Chrysler Building and Empire State Building.

Heavy rain near the Minnesota/Canada border may help control some fires, but storms could also bring strong winds and lightning, potentially sparking new fires and worsening conditions. Similarly, passing showers and thunderstorms in Ontario on July 17 are unlikely to extinguish the wildfires, with winds and lightning posing additional risks.

Health officials warn that everyone may experience negative effects from particulate matter in the air, with members of sensitive groups at risk for more serious health impacts. Kai Chen, an associate professor of epidemiology at Yale School of Public Health, advised that individuals who work outdoors, are sensitive to smoke, or belong to high-risk groups should wear N95 masks, which filter at least 95% of airborne particles.

In response, New York City Mayor Zohran Mamdani announced that free KN95 masks are available at hundreds of locations throughout the city.

The ongoing situation has also affected local events; for example, a baseball game against the Pittsburgh Pirates has been rescheduled as part of a split doubleheader on Saturday, July 18.

Authorities across affected regions continue to monitor the wildfire activity and air quality closely.

Sources