There’s Something in the Air…You’re Breathing

Here’s how to stay on top of these five indoor air problems and breathe easier this winter and beyond.

On a lark last winter, our family borrowed a friend’s radon detector to check levels of the radioactive gas inside our Kelowna home. I had heard that radon could be a concern in BC’s Okanagan Valley, but I didn’t really think we’d be impacted. But as soon as we deciphered the strange new units of measurement on the monitor (Becquerels per metre cubed), we realized we had a big problem: our readings ranged from 600 to 2,400. Acceptable numbers in Canada are under 200 Bq/m3, so our house was exposing us to between three and 12 times the acceptable amount of the potentially deadly gas, depending on the day and whether we were in the basement or upstairs.

After some frantic Google searches (such as “radon, deadly?”) and more than a little freaking out—fact: radon is the second leading cause of lung cancer and accounts for 16 percent of lung cancer deaths in Canada annually—we called in a radon mitigation expert. He fixed the problem by sealing our basement crawl space with plastic and venting the gas out of the house.

“We know that houses are being built to meet new energy standards,” says Graeme Cooper, owner of Point-The-Way Radon Services, a radon testing and mitigation company in the Okanagan Valley. “They’re better insulated, but these household contaminants can more readily build up in the home.” A house that’s essentially better-sealed traps the radon. Larger-footprint homes cover more ground (literally) and can bring in more radon from the soil or bedrock.

Since Canadians spend 90 percent of their time indoors, it’s important to ensure that the air inside your sanctuary is as clean as possible. But depending on where your home is located, how it’s built, and what you’re doing inside it, indoor air quality can be compromised.

Radon isn’t the only thing we need to be aware of as we head into winter, says Tara Kahan, an indoor air quality expert and Canada Research Chair in Environmental Analytical Chemistry at the University of Saskatchewan. “A lot of pollutants can get up to quite a few times higher indoors than outdoors.”

These are the top five indoor air quality problems, according to the experts—and what to do about them.

(Related: The Worst Canadian Cities for Air Pollution)


Radon is released from the radioactive decay of uranium, radium and thorium, which are present in soil and bedrock in Canada. All buildings have some amount of radon, but according to 2012 data from Health Canada, seven percent of homes have high levels. (Updated data will be coming out in late 2022.) What’s more, radon can vary from home to home, even in the same neighbourhood, and more data is needed to see what levels are like across Canada. Cooper says that in the Okanagan region, where he is, tests indicate it’s actually closer to one third of homes, but geographic “hot spots” are hard to identify because different regions aren’t being systematically tested and properly compared across Canada.

Health Canada recommends that every house in Canada test for radon. This involves purchasing an Alpha Tracker ($60, and monitoring radon levels over a three-month period to account for seasonal fluctuations—in winter, the warmer air inside a home creates a pressure difference that draws in more radon from the ground, explains Cooper.

Mitigation, which will set you back between $3,000 and $5,000, involves “active depressurization,” which changes the pressure under a home’s foundation, or covering a dirt floor or crawlspace to capture the radon and vent it outside.

It’s a hefty price tag, but for some homeowners, the peace of mind about health effects is worth it. “We know through intensive studies that if someone lives in a household with high radon they have a one in 20 risk of developing lung cancer,” says Cooper. “If they smoke, it goes up to one in three.”

Particulate matter

Combustion from cooking on a gas stove, or even from lighting candles or incense, is a source of particulate matter inside homes. (Most wood-burning fireplaces and woodstoves do not contribute significantly to particulate matter in your indoor air, as long as they’re built with a proper flue, chimney and venting.) Indoor air is also influenced by what’s outside, and can include pollution from traffic, industry or forest fire smoke.

Particulate matter of a certain size (2.5 micrometres or smaller) can get lodged deep in your lungs, which then mount a defence to eject it—causing asthma symptoms. This can also trigger an inflammatory response throughout the body that impacts other organs, including the heart and brain, says Michael Brauer, a professor in the Faculty of Medicine, School of Population and Public Health, at the University of British Columbia.

“Particulate matter seems to impact everything from the birthweight of babies to increasing dementia in elderly people,” says Brauer, who studies air quality and health. “You really want to limit your exposure.”

He suggests lighting candles and incense indoors in moderation, if at all. When cooking, always use the hood fan (one that vents outside is best) and crack a window, weather dependent. To make sure any outdoor air that’s coming inside is as clean as possible, change out furnace and air conditioner filters regularly, and consider upgrading to HEPA filters inside your furnace if possible.


Mould occurs naturally outdoors, and it’s not uncommon to find it in moist rooms such as bathrooms and basements, says Brauer. In fact, 40 percent of homes probably have some level of mould, as it can thrive indoors if there’s enough moisture.

Mould is linked to respiratory symptoms such as coughing and wheezing, and it can exacerbate asthma, says Brauer. These symptoms may or may not be reversible, depending on the length of exposure.

What people can do is eliminate obvious mould patches, turn on the bathroom fan when showering or bathing and use a dehumidifier to keep humidity below 45 percent in problem rooms. Fix any leaking pipes or appliances, too—it doesn’t take much for mould to take hold. Watch for water stains on the ceiling, or any drywall bubbling or bloating. Buckling hardwood floors near your fridge are also a giveaway for leaks!

Consumer products

“A lot of things that we buy or do can emit VOCs,” says Kahan. “Generally, if you smell something, it’s some kind of organic compound in the air.”

We regularly spray volatile organic compounds (VOCs) into the air in our homes without giving it any thought, whether that’s spritzing the dog’s smelly bed with Lysol or overusing household cleaners as a pandemic holdover. New furniture or carpet can off-gas for weeks.

But these gasses can have short-term neurological and neuro-behavioural effects—like a experiencing a headache or losing your concentration after breathing in paint fumes, says Brauer. The best solution is to be intentional about product use, and to crack a window when cleaning or cooking, or after that new boxed mattress arrives. Owners of new houses—or newly renovated homes—should be aware that everything from cabinets to new flooring can off-gas for weeks.

Lack of airflow

“Airflow” transformed from new buzzword to common knowledge during the pandemic, when health officials warned that being in spaces with poor ventilation, such as bars or crowded classrooms, increased the risk of contracting COVID-19. But stagnant air in homes is a concern, too, and for reasons outside of COVID, says Justin Liberman, director of operations for Air Quality Canada, an environmental consulting firm.

“We look at CO2, which is effectively a tracer gas for airflow,” says Liberman. “So, more CO2 indicates a lack of airflow.”

The health impacts of high CO2 (or carbon dioxide) levels—feeling tired or sluggish—are usually minor and reversible. But good air circulation is important, since it keeps a fresh supply of oxygen moving through the house. If your furnace doesn’t already have an HRV (heat recovery ventilation system), you might consider getting one. It’s an add-on that brings in more fresh air from outside, says Liberman—but it can set you back $2,000 to $4,000.

Easy indoor air-quality hacks

  • Change furnace and air conditioner filters every three months when appliances are in use, and hire professionals to clean the furnace ducts every few years.
  • Make sure your home’s carbon monoxide (CO) monitors and smoke detectors are working properly.
  • Use bathroom fans when showering and the hood fan when cooking.
  • Consider a portable air filter for rooms you spend a lot of time in, such as a bedroom.

The low-down on air quality monitors

Unless you suspect your home has multiple air quality problems, experts don’t recommend buying an all-in-one monitor for the home. It can be difficult to interpret the data, for one, as air is constantly in flux. What’s more, people tend to become a slave to the monitor, and it can increase anxiety. The one caveat is radon: Experts agree that everyone should purchase a radon monitor to track radon levels over three months.

Next: A Guide to the Best House Plants, According to Science

Originally Published in Best Health Canada