Is wildfire smoke worse than smoking cigarettes? What experts say

As smoke from Canadian wildfires spreads dangerous air quality across the Great Lakes and Northeast, doctors say the cigarette comparison can help explain the hidden health risk in the air.

Smoke from wildfires in Canada and Minnesota has been pouring into the Great Lakes and Northeast, turning the sky hazy and pushing air quality to dangerous levels for millions of people.

As more people check the Air Quality Index before heading outside, doctors say one comparison can help explain just how unhealthy the air can become: cigarettes.

“Neither wildfire smoke nor cigarette smoke exposure is good,” Dr. Jonathan M. Tan, division chief of General Anesthesiology at Children’s Hospital of Philadelphia, told AccuWeather.

Tan said the comparison is not perfect, but it is useful because many people already understand the danger of smoking.

“Cigarette smoking is something most people already understand in a tangible way — we know roughly what a pack a day does to a person’s health,” Tan said. “That familiarity gives us a useful, if imperfect, yardstick for talking about air quality.”

The comparison centers on PM2.5, the tiny particles in wildfire smoke that can travel deep into the lungs. These particles are also found in cigarette smoke and are among the biggest health concerns during smoky air outbreaks.

“Scientists have found that an air quality reading of about 20 on the AQI scale is roughly like smoking one cigarette a day,” Tan said. “So when the AQI climbs into the 150+ range for a full day outside, that’s in the ballpark of 7 to 9 cigarettes.”

During extreme fire events, the number can climb much higher.

“We’ve seen this play out in real fires,” Tan said. “During the 2025 Eaton Fire in the Los Angeles area, particle pollution levels were so high they translated to roughly 22 cigarettes in a single day.”

Wildfires burning in northern Minnesota and Ontario, Canada, have prompted evacuations and sent thick smoke across the border. This week’s smoke outbreak has already produced some of the worst air quality in North America.

But Tan warned that the cigarette comparison may actually understate the risk from wildfire smoke.

“A cigarette has a filter,” Tan said. “The air outside your front door during a wildfire doesn’t.”

Another key difference is how the exposure happens. Cigarette smoke exposure is often chronic, building up day after day and year after year. Wildfire smoke usually comes in bursts, lasting days or weeks before the air clears.

Tan said repeated smoke events are making that distinction less clear for some communities.

“Wildfire smoke tends to be episodic — it spikes for days or weeks during a fire event, then clears,” Tan said. “Smoking and secondhand smoke exposure, on the other hand, are usually chronic — day after day, year after year. That said, back-to-back fire seasons are starting to blur that line for people who live in wildfire-prone regions.”

Children, older adults and people with heart or lung conditions face the highest risk when smoke fills the air. Health experts recommend staying indoors, closing windows, using air filtration when possible and avoiding outdoor exercise on smoky days.

Tan said the bottom line is simple: treat wildfire smoke like secondhand smoke you cannot control.

“On a wildfire smoke day, treat it like you would a day of secondhand smoke exposure you can’t control," Tan said. "Limit time outside, especially for kids, older adults and anyone with heart or lung conditions."

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