Wildfire Smoke Spreads Across Midwest and East Coast, Prompting Health Warnings

Heavy smoke from wildfires burning primarily in Canada and northern Minnesota darkened skies Thursday from the Great Lakes region to parts of the East Coast, reducing visibility and driving air-quality alerts. The National Weather Service said a lingering high-pressure system trapped the smoke near the ground, producing unhealthy to hazardous conditions in Michigan, Minnesota, Illinois and New York, among other states.

Meteorologists in Detroit reported visibility dropping to about half a mile and warned that even if northwest winds clear the skies later in the week, the smoke could return until the fires are extinguished, potentially taking months.

Local officials urged residents to remain indoors, limit strenuous outdoor activity, and use N95 or KN95 masks when outside. New York City opened cooling centers, moved school and park activities indoors, and distributed tens of thousands of free masks at transit hubs. In Chicago and Detroit, city workers and the public were seen wearing masks as the haze obscured skylines.

Health experts noted that fine particulate matter from wildfire smoke can penetrate deep into the lungs and enter the bloodstream, increasing the risk of heart and lung problems and other long-term health issues. A recent study estimated that such exposure contributes to roughly 24,000 deaths annually in the contiguous United States.

In Minnesota, fire crews continued to battle spreading blazes, and the Boundary Waters area remained closed while rescue efforts focused on locating any stranded hikers. The Royal Canadian Air Force evacuated several teenagers and staff from a provincial park fire near the border.

State and local health officials, including Philadelphia’s public health commissioner, warned that the air quality could spike to “very unhealthy” levels in parts of New York State and urged the public to avoid marathon-training or other intense exercise outdoors.