A cloud of smoke from Canadian wildfires suddenly blanketed Minnesota on Sunday evening, marring what had otherwise been a sun-drenched weekend and leaving some residents wondering whether the misery of last summer was starting all over again.
A thick haze of smoke had repeatedly hung over cities in the Midwest and on the East Coast throughout the summer last year, leaving some communities breathing air so polluted that schools were closed and sporting events canceled.
For now, experts say that a similar pattern has indeed appeared to have emerged. “We’re expecting a pretty active wildfire season in Canada,” said David Brown, an air quality meteorologist at the Minnesota Pollution Control Agency. “But we don’t think it will be quite as extreme.”
Mr. Brown said a key difference was that drought conditions in Canada were not as extensive as they were last year, when fires raged in the provinces of Quebec and Ontario. For now, he added, people on the East Coast appear unlikely to endure the kind of periods of highly polluted air that startled many people last year.
Air pollution from wildfires in the northern regions of the United States has worsened over the past decade as a result of warming temperatures and drought, experts said. Periods of poor air quality can be particularly dangerous for toddlers, older people and those with respiratory and cardiovascular conditions.
“Unfortunately, it seems like these events are becoming more and more common,” said Jesse Berman, an environmental epidemiologist at the University of Minnesota. “We need to be aware of it and adapt to the reality that smoke will blanket parts of the state during the summer.”
Last year, Minnesota’s pollution agency issued 21 air quality alerts, a record high. Such advisories put people on notice of pollution that can be harmful. The second-worst year was 2021, when the agency issued 16 alerts. Similar alerts were issued in states across the Midwest and Northeast last year.
The sudden burst of smoky air caught many Minnesotans off guard at the end of an otherwise pleasant weekend filled with people swimming in lakes, riding bikes and running outdoors. It was one of the warmest weekends so far this year.
Dr. Aika Shoo, a radiation oncologist in Minneapolis, said that when her eyes grew itchy on Sunday night, she had initially assumed it was allergies. Then she smelled the smoke and a feeling of dread came over her.
“I couldn’t sleep because my eyes were all puffy,” she said. “Weather patterns are changing so drastically that maybe this will be the new normal.”
When alerts are in effect, people should limit their time outdoors and avoid strenuous exercise outside, experts said. They also suggest closing windows, and using air-conditioners and commercial air filters.
Isaac Muscanto, who lives in a suburb of Minneapolis, said the burst of smoky air had hampered his triathlon training plans.
“I am very annoyed I have to run on a treadmill today,” he said on Monday. While poor air quality is an inconvenience for Mr. Muscanto, he said he worried more for some of his patients at the community health center where he works as a clinic assistant.
“I get nervous when I think about people who might experience serious consequences from the air quality, especially if they have to be outside,” he said.
By Monday night, this blast of smoky air was expected to clear out.
