Wildfire smoke can prompt air quality alerts and warnings to take shelter indoors. But new research shows that surfaces within homes can act as reservoirs for hazardous volatile organic compounds (VOCs) produced by wildfires, causing long-term exposure to these chemicals even when indoors. However, through elbow grease and simple cleaning practices, VOCs from wood smoke can be reduced in a home, lowering the risk of health effects.
Volatile organic compounds are types of chemicals that dominantly sit in the gas phase. This means they are in the air, says Delphine Farmer, a professor of chemistry at Colorado State University and a co-author of the study. There are a huge array of VOCs, some toxic, some harmless, she says. There are also many sources for VOCs, including cooking, vehicle exhaust, and plants.
Burning wood—whether from a wildfire or from the fire pit in your backyard, produces VOCs. Some of the VOCs found in smoke, like benzene and furans, are toxic.
The trouble with wildfire smoke is that no house is perfectly sealed from the outdoors. “All houses are leaky,” says Farmer. “The older the house, the less well sealed it is.”
Your choice of building materials can impact your cottage’s wildfire resilience
VOCs from wildfire smoke can enter a home or cottage through cracks around windows, foundations, and building joints. Once inside, VOC can attach to interior surfaces, the research showed.
That said, the study team found that a combination of simple cleaning techniques, including dusting surfaces, tables, and countertops, and then vacuuming and mopping floors, was able to reduce VOC concentrations indoors. The team used a cleaning recipe recommended by the Red Cross to remove the scent of smoke indoors, a mixture that included a general multipurpose cleaner and a heavy duty cleaner called trisodium phosphate.
“Based on the chemistry, I don’t really think it matters what type of cleaner you use, what quality of vacuum you use,” Farmer says—so don’t worry about getting the fanciest cleaning equipment. It was very clear that the simple combination of removing dust and some kind of wet surface was very effective, she says. (She does suggest avoiding any cleaners that contain bleach or peroxide.)
Your guide to cleaning just about everything at the cottage
Time is the important factor when it comes to cleaning up after a wildfire: the sooner you clean, the better. “The reason for that is you don’t want to give those molecules time to bury into the drywall or into the surfaces inside your home,” says Farmer. “You want to catch them while they’re still on the surface.” She recommends doing a surface clean as soon as possible after a smoke event. If wildfire smoke lingers for an extended period of time, do a surface clean every few days, she says.
Don’t rely on your nose to tell you if you’re in the clear from wildfire smoke. “Smell works really well as an indicator for fresh smoke,” says Farmer. “But when a fire moves over long distances, when it’s transported from one part of Canada to another, the chemistry that happens actually removes some of the compounds that give it its smell.” Farmer points to how residents of southern Ontario and Montreal might be able to see the haze of wildfires from northern Ontario but not smell it. “That doesn’t mean the pollutants aren’t there,” she says.
Cottage owners interested in getting a snapshot look at their local air quality can use a free online map called the Purple Air Network. The data for the map is provided by community scientists who install sensors on their homes to provide live readings of air pollution. It’s a helpful tool that cuts out the guesswork in assessing air quality.
Cottagers with a wood stove or fireplace might be wondering if they should also worry about these features producing hazardous VOCs. This is where you can trust your nose. “If you have a well-tended, appropriately designed and installed wood stove, you shouldn’t be smelling wood smoke,” says Farmer. “The smoke should be leaving the building and going outside.”
But if you can smell your fireplace or stove? “Then you have a leak,” says Farmer. “And that means the exact same VOCs are in your house.” And they’re going to have the same impact as the VOCs from her recent research.
Tips for improving indoor air quality
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