Ontario Tech researchers describe possible long-term health risks from repeated wildfire smoke exposure

Ontario Tech University researchers in Oshawa say they are examining whether repeated exposure to wildfire smoke may be linked to longer-term health problems, including heart disease, stroke, adverse pregnancy outcomes, cognitive decline and psychological distress. The comments were published in a university news release dated Sept. 10.

Wildfire smoke can affect air quality in communities thousands of kilometres from the fires, and the university’s researchers say some health effects may last beyond the days when skies are visibly hazy.

A key concern is PM2.5, the fine particulate matter found in wildfire smoke. Dr. Caroline Barakat, a professor in Ontario Tech’s Faculty of Health Sciences, said PM2.5 particles can travel deep into the lungs, enter the bloodstream and contribute to inflammation throughout the body.

Barakat said researchers now recognize wildfire smoke as more than a short-term respiratory irritant, and that growing evidence suggests repeated exposure may be linked to a range of longer-term outcomes, including cardiovascular effects and mental health impacts.

She also said her research has found that children exposed to higher levels of fine-particulate air pollution were more likely to develop chronic inflammatory conditions such as hypertension and arthritis later in adulthood.

“ The effects of air pollution are not always immediate, and early-life exposures can shape health decades later,” Barakat said.

Dr. Mika Nonoyama, an associate professor in the Faculty of Health Sciences and a registered respiratory therapist, said healthy people can experience temporary symptoms during periods of heavy smoke, including throat irritation, burning eyes, coughing and mild shortness of breath. She said those symptoms typically improve when exposure decreases.

Nonoyama said people with asthma, chronic obstructive pulmonary disease (COPD) and other respiratory illnesses can be affected more severely because their airways may already be inflamed or damaged. “Wildfire smoke can exacerbate airway inflammation and increase symptoms for people with asthma or COPD,” she said.

She said flare-ups can reduce exercise tolerance, interfere with daily activities, increase the need for rescue medications and, in some cases, lead to emergency department visits and hospitalizations.

Barakat said children, older adults, pregnant individuals and people with underlying heart or lung conditions are among those most susceptible to smoke-related health impacts. She said lower-income households, people experiencing homelessness, outdoor workers and those without access to clean indoor air may be disproportionately affected.

Barakat added that Indigenous communities can face additional challenges, particularly in regions experiencing repeated smoke events, evacuations and disruptions to essential services and community life.

Nonoyama said people should not rely solely on what they can see outside when assessing wildfire-smoke risk. “Wildfire smoke can be harmful even when visibility appears acceptable,” she said.