Radon levels putting more than 10 million Canadians at a higher risk of lung cancer, report says. What to know about the gas, health concerns

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High levels of radon gas in Canadian homes are creating a concern across the country, with a new report suggesting people are being exposed at unacceptable levels. Additionally, the data indicates more than 10 million people across the country could be at higher risk of developing lung cancer.

The 2024 Cross-Canada Survey of Radon Exposure from the University of Calgary, published on Wednesday, shares there are 10.3 million Canadians living in places with high levels of the radioactive gas. The report shows nearly 18 per cent of homes in the country contain radon levels that exceed 200 Bq/m3, which is what Health Canada advises.

"In the 12 years since we released the first Cross Canada Radon Report, evidence has continued to emerge showing that the number of high-radon homes has been increasing," Pawel Mekarski, head of the radon technical operations section for Health Canada's National Radon Program, says in a statement.

Aaron Goodarzi of the University of Calgary adds the report concludes Canadians are "among the most highly radon-exposed people on Earth." He noted this must urgently be addressed to "avoid a future of prevalent, but otherwise avoidable lung cancers."

What is radon?

Radon is a colourless, odourless and radioactive gas. Health Canada notes it comes from the breakdown of uranium in soil and rock, and it's also invisible as well as tasteless.

While radon released into the air outside isn't a concern since it's quickly diluted, the radon that accumulates within indoor spaces, like homes, can become a health risk. People who work underground, like in subways, tunnels or mines, might also be at risk of high radon exposure.

Is radon dangerous?

Radon is the number one cause of lung cancer in non-smokers, according to Health Canada. Moreover, the gas is a known cause of cancer by The International Agency for Research on Cancer, according to the Canadian Cancer Society.

The naturally occurring gas is much more likely to cause lung cancer in people who smoke, too, the World Health Organization (WHO) states. Smokers are around 25 times more likely to be at risk from radon than non-smokers.

Health Canada estimates around 16 per cent of lung cancer deaths are related to a person being exposed to radon in their home. The Canadian Cancer Society suggests that might equate to around 3,300 lung cancer deaths related to radon each year in the country.

How does radon get into your home?

Radon can enter a building of any age, new or old. The gas can enter homes through any opening where the house contacts the ground. That might include cracks in the foundation or walls, construction joints, gaps around service pipes, support posts, window casements, floor drains, sumps or cavities inside walls.

Typically, the air pressure inside a home is lower than in the soil surrounding the foundation. This difference in pressure causes air and gases — including radon — to escape the soil and enter the building.

Drinking water can sometimes also carry more radon than other sources of water. The WHO indicates drinking water taken from groundwater sources, like wells and springs, might contain more radon than surface water from rivers or lakes.

How can you test radon levels in your home?

All homes in Canada have radon in them, Health Canada notes, but concentrations vary greatly across the country and house-to-house. Usually, radon levels will be higher in areas where there is a higher amount of uranium in underlying rock and soil.

The only way to be sure of the radon levels inside your building are to conduct a test. You can either purchase a radon test kit you use yourself or hire a professional who will run a long-term test of at least three months.

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The best way to test radon levels in your home is by conducting the test in the lowest lived-in level of the home. This will let you see the most-accurate impact the gas might be having on the health of you and your family.

According to Health Canada, this is the lowest-level room that is used or occupied for more than four hours a day. If you only use your basement to do laundry once a week, for example, it's likely not the best place to test because your exposure time wouldn't be long enough to cause significant health effects.

How can you reduce radon levels in your home?

If the radon levels in your home exceed 200 Bq/m3, it's probably a good idea to make a fix. After testing, Health Canada recommends hiring a mitigation professional certified under the Canadian National Radon Proficiency Program. They will help you find the best way to reduce the radon level in your home.

Sub-soil depressurization is the most common way to reduce radon levels. This works by sucking air and other gases from beneath the foundation of a home and exhausting it outside.

Other control methods might include sealing cracks in the foundation or walls and using air cleaners. Then, you can install ventilation — such as fans, blowers and suction devices — to remove radon from certain rooms.

Should the average Canadian worry about radon?

While radon continues to be a "critical public health concern," Health Canada suggests "radon risk reduction is easy to address through testing and mitigation." Moreover, the federal government estimates only around seven per cent of Canadian homes may have high radon levels — and that significantly varies across the country.

Overall, the number of homes in Canada that might have higher radon levels are relatively low. In the six largest Canadian metropolitan areas, the percentage of homes with radon levels that exceed 200 Bq/m3 is under 20 per cent. In fact, the Toronto and Vancouver areas have less than five per cent of homes that go over that recommendation:

• Toronto Metro Area: One in 22 properties (4.5 per cent) exceed 200 Bq/m3

• Montreal Metro Area: One in six properties (17.4 per cent) exceed 200 Bq/m3

• Vancouver Metro Area: One in 113 properties (0.9 per cent) exceed 200 Bq/m3

• Ottawa-Gatineau Metro Area: One in six properties (17 per cent) exceed 200 Bq/m3

• Calgary Metro Area: One in six properties (15.5 per cent) exceed 200 Bq/m3

• Edmonton Metro Area: One in six properties (16.2 per cent) exceed 200 Bq/m3

Outside of those areas, there are a large number of Canadian municipalities with particularly elevated average residential radon levels. In the following cities, at least one-quarter to one-half of residences have indoor radon levels that exceed 200 Bq/m3.

• Whitehorse

• Nelson, B.C.

• Kelowna, B.C.

• Prince George, B.C.

• Vernon, B.C.

• Penticton, B.C.

• Trail, B.C.

• High River, Alta.

• Okotoks, Alta.

• Strathmore, Alta.

• Regina

• Brandon, Mant.

• Winnipeg

• Thunder Bay, Ont.

• Kingston, Ont.

• Sherbrooke

• Bathurst, N.B.

• Halifax

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