CHICAGO, ILLINOIS – JUNE 03: An aerial view shows smoke from Canadian wildfires dimming the downtown skyline on June 03, 2025 in Chicago, Illinois. The smoke is causing air quality alerts in parts of Minnesota, Iowa and Wisconsin and is visible in Illinois, Michigan, Ohio, Pennsylvania and West Virginia. (Photo by Scott Olson/Getty Images)
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The northeastern U.S. has, for the second time in recent history, experienced abnormally poor air quality for an extended period of time. An unusual phenomenon for the region, but not so abnormal for major global cities like Beijing and Delhi.
The repeat occurrence has prompted questions about whether or not the region should start bracing for “smoke season”, in the same way the Midwest prepares for snow days or tornado season, and the Southeast prepares for hurricane season.
Experts say that for the Northeast in particular, the answer is yes. But it is not going to be a nationwide seasonal phenomenon. In part because California and the Pacific Northwest have already transitioned from extreme wildfires being a seasonal threat to a year-round one.
For the northern regions of the Midwest, and the northeastern region, it’s becoming a compounding problem to air quality concerns stemming from climate change. That’s according to Noah Diffenbaugh, a professor of earth system science and senior fellow at Stanford University.
“As far as these very pronounced, continental scale smoke events. What is clear is the effect they are having on the total pollution burden. In recent years, the wildfire smoke has become a big factor in the number of days that are out of compliance with the Clean Air Act,” he said.
“It’s not just that we’ve had these natural fire smoke events, where millions of people are being exposed to smoke plumes and orange skies and other imagery we’ve seen. We do know that these are having a real impact on air quality and on human health,” Diffenbaugh said.
Things like air filters, cycling air in buildings and cars, checking window seals, stocking up on face masks, and keeping vigilant on medical needs and medicines are all things people need to pay attention to and practice.
And should we expect this to happen more often? Yes, Diffenbaugh said.
“As global warming continues…the more we can expect these large smoke events and their health burdens to intensify,” he said. “Because of the distance over which the smoke fans blow, we can expect these air quality burdens from wildfire smoke to also increase with global warming.”
But it is not seasonal in all parts of the United States, he added. California has begun to prepare for wildfires year-round. But Canada’s wildfires, which are the ones impacting the Northeast, are more seasonal because the snow and cold keep the fires at bay during colder months.
That means the Northeast and northern parts of the Midwest should be preparing for the poorer air quality days to happen in the summer months, which means making changes as needed to keep people safe indoors, according to John G. Allen, director of the Healthy Buildings Program at Harvard University.
Allen has been focused on the idea that buildings can protect humans from the environment from years, and says the changes to ensure better filtration can serve year-round, including during respiratory virus season.
“It’s true that other parts of the world experience these levels. But it’s also really quite different because of what’s causing it,” Allen said. “We’ve seen with hurricanes…now, they’re just more frequent and more intense. This is all driven by the changing climate. It’s inarguable at this point.”
NEW DELHI, INDIA – OCTOBER 29: A commuter walks near India Gate amid heavy smog pollution on October 29, 2025 in New Delhi, India. Delhi is once again blanketed by hazardous smog following the Diwali festival, as pollution levels spike to the “very poor” and “severe” categories, with air quality indexes far exceeding safe limits. The crisis, which is driven by firecracker use, emissions, and seasonal crop residue burning has prompted emergency measures like cloud seeding. (Photo by Ritesh Shukla/Getty Images)
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No season yet
“I don’t know if there’s a wildfire season, per se. It seems like it’s just happening a lot and more frequently and all over the place,” Allen said.
It’s why thinking of buildings as “tools” to manage the events is the key. That includes ensuring better filtration systems, building or renovating spaces to have better air circulation, and ensuring more quality in things like window sealings – all to keep the air inside cleaner and safer than what is happening outside.
“The problem is that most buildings are not improving their filtration. And so when it’s 500 (Air Quality Index Value), indoors might be 200. Because the building’s not doing its job. It doesn’t cost much, and it’s very achievable for these buildings to put the enhanced filtration in place that can really protect people,” Allen said.
But doctors think adopting a seasonality mindset could be helpful. It can help prepare people for managing their health conditions – especially those vulnerable to poorer air quality or extreme heat.
Dr. Chethan Sarabu, director of clinical innovation for the Health Tech Hub at Cornell Tech, said it’s too early to determine if this will actually be a seasonal occurrence, but that “it has a public health benefit.”
That means thinking about children’s health, ensuring asthma patients take necessary precautions when going outdoors, and thinking about how to stay safe indoors.
He previously lived in California just as the wildfires began to become more intense, and said that while they face a year-round threat, being in parts of the country where snow covers the ground helps keep the fires away for much of the year.
“It’s possible for us to consider a season and just anticipating that for the warmer weather – wildfire smoke plus pollution equals bad air quality,” Sarabu said.