VANCOUVER — British Columbians are being told to prepare themselves for the worsening of a dense shroud of wildfire smoke that has descended over the province, with health experts saying the dangerous impacts of the pollution might not be immediately apparent.
Forests Minister Ravi Parmar told a briefing on Wednesday that the smoke would be a "major factor" in the next 24 to 72 hours, with more arriving in the central and southern Interior in the evening or on Thursday, and reaching the Fraser Valley by Friday.
"We should expect wildfire smoke to come south in the days ahead," Parmar said, adding that the smoke was coming from fires in B.C., Yukon and the Northwest Territories, as well as from the United States.
After a summer of relatively clear skies, Metro Vancouver residents woke to a pall of smoke on Wednesday that blotted out the North Shore mountains as it worsened through the day.
Sarah Henderson, scientific director of Environmental Health Services at the BC Centre for Disease Control, told the briefing there would be a significant amount of smoke across most of the province over the next three days, and ongoing high temperatures would potentially worsen its health impact.
"Both heat and wildfire smoke are stressors on the body and simply put, heat makes wildfire smoke worse and wildfire smoke makes heat worse," she said.
"So, when these two things happen together, we see a bigger impact than when either of them is happening alone."
She said that while most people would only experience "transient" mild symptoms, wildfire smoke could also have a longer-lasting health impact.
"So, even after the smoke goes away, it leaves a thumbprint or a fingerprint on our bodies that can stay with us for years."
Henderson said that the forecast was for a “concentrated amount of smoke” to arrive in the central Interior and less on the coast, but it could not account for new wildfires.
“The best advice I can give you is to be prepared for smoke in the days ahead no matter where you live in the province," she said.
She recommended closing doors and windows and running an indoor air cleaner, which could be purchased or homemade, based on instructions on the BCCDC website.
She recommended against strenuous outdoor exercise, wearing a well-fitted N95 mask or similar respirator, and drinking plenty of water to reduce inflammation.
"Don't try to tough it out. If your body is telling you that you're struggling with the smoke, take measures to reduce your exposure," she said.
Environment Canada had earlier expanded air-quality bulletins to more than 30 areas stretching from Metro Vancouver to the far northeastern corner of B.C., while higher-level warnings were in effect across most of Alberta and a portion of northwestern Saskatchewan.
A bulletin from Metro Vancouver advised residents to avoid or limit outdoor activity due to the elevated levels of fine particles in the air, while the Vancouver School Board said it had moved all activities indoors due to the smoke.
University of British Columbia sport and exercise medicine professor Michael Koehle said the best practice residents could adopt during times of poor air quality was to monitor the latest local conditions on federal and other information resource sites.
Koehle added that while people exercising outside may not immediately notice problems breathing, they were being exposed to particles that may lead to long-term issues such as heart and lung disease.
"Often in the moment, we don't feel that much different," he said. "You can smell it, but compared to other pollutants, in the moments you don't feel as much coughing and chest tightness as you would with, say, ozone air pollution.
"The particulate matter air pollution can increase our risk of lung disease and heart disease, and even Type 2 diabetes and dementia, but it takes time to do that."
If people have to go outside, Koehle said he recommended short periods of more intense workouts rather than long periods of mild or moderate exercise, as it is the length of exposure that increases the dose of pollutants a person inhales.
Metro Vancouver said the smoke was linked to high humidity and a heat wave that saw the Fraser Canyon community of Lytton tie the record for the hottest temperature ever recorded in Canada during the month of September.
The temperature of 40 C on Tuesday also broke Lytton's daily record of 39.6 C set in 2022, while 11 other B.C. communities, including Cache Creek, Kelowna, Princeton and Whistler, also saw local records fall.
Heat warnings were in place Wednesday for nine areas of the province, including inland locations of the north and central coast, as well as the North and South Thompson, Fraser Canyon and Boundary regions.
Environment Canada said the heat in the southern Interior is due to a ridge of high pressure "anchored" over the region, creating a "moderate risk" to public health.
The heat warnings were expected to end by Thursday for the southern Interior and Friday for inland areas of the coast.
In Alberta, Environment Canada has suggested people limit their time outdoors and reschedule outdoor events.
The weather agency said the smoke is causing "very poor air quality and reduced visibility in some areas."
This report by The Canadian Press was first published Sept. 3, 2025.
Chuck Chiang, The Canadian Press
