More than 100 million Americans are currently under air quality alerts as smoke from wildfires in Canada and northern Minnesota spreads across parts of the United States. The smoke releases microscopic particles into the atmosphere that pose serious health risks.

Shifting winds have carried thick haze into major metro areas across the Great Lakes, Northeast, and Mid-Atlantic regions, reducing visibility and pushing pollution levels into unhealthy and hazardous ranges. Officials in cities from Chicago to New York to Washington, D.C. have urged residents to limit outdoor activities or wear masks during peak pollution hours.

According to the Canadian Interagency Forest Fire Centre (CIFFC), based in Winnipeg, there were 949 active wildfires as of Saturday afternoon, affecting all but one of Canada’s 10 provinces and three territories. Ontario and the Northwest Territories account for more than one-third of these fires. Prince Edward Island is the only Canadian province without active wildfires.

Less than 20 percent of the fires are considered "under control" or "being held," while over 200 are fully "out of control" and expected to continue burning. The remainder are out of control but being monitored.

In addition, more than a dozen active fires in northeastern Minnesota have burned an estimated 77,000 acres in and around the Superior National Forest and Boundary Waters Canoe Area Wilderness, according to local media reports.

Health experts warn that even a 10-unit increase in PM2.5 particulate matter can lead to increased emergency room visits and hospital admissions for heart attacks, strokes, arrhythmias, and severe breathing problems related to asthma, chronic obstructive pulmonary disorder (COPD), or bronchitis.

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