Exposure to deadly radon gas in Canadian homes continues to grow, according to a nationwide study conducted by University of Calgary researchers.
Nearly 18 per cent of Canadian homes contain radon levels at or above Health Canada’s action guideline of 200 becquerels per cubic metre (Bq/m³) for the carcinogenic gas, according to the national study.
The cross-Canada survey of radon exposure gathered data from more than 70,000 residential buildings across the country. The results show the number of Canadian homes with radon levels above the safety guideline has more than doubled since the last national study 12 years ago.
Radon, an invisible gas undetectable to human senses, is the second-leading cause of lung cancer behind smoking, estimated to kill 3,000 Canadians every year. The gas rises from radioactive sources in the ground and can be trapped in homes where it can accumulate.
“Alarmingly, this report concludes that Canadians are among the most highly radon-exposed people on Earth,” said Dr. Aaron Goodarzi, the scientific lead of the study and director of Evict Radon, an organization of Canadian scientists and scholars focused on the nation’s radon issue.
“Canada has among one of the highest rates of lung cancer globally, despite one of the lowest rates of tobacco smoking.”
Two in five lung cancer diagnoses in Canada are of a “non-tobacco origin,” says Goodarzi, who led the study. That, he says, points to high exposure from sources such as indoor air where Canadians live, work and play.
No areas of Canada are completely free of high radon exposure risk, researchers found, and radon levels can differ drastically from house to house on the same street.
The IJB has partnered with Evict Radon since 2021 for the Bureau’s ongoing Invisible Threat series which has detailed how the federal government’s radon advice to Canadians creates a false sense of security while lax building codes allow dangerously high levels to be trapped inside newly built homes.
The IJB’s first radon article led to a 5,400-per-cent increase in Canadians signing up to be part of Evict Radon’s national radon study.
An estimated 10.3 million Canadians live in houses with “high radon,” based on Health Canada’s safety guideline of 200 becquerels per cubic metre, says the new study.
But consistent exposure to just half of that guideline – 100 becquerels per cubic metre – triggers a 16 per cent increase in developing lung cancer risk over a lifetime, according to widely acknowledged academic research.
The World Health Organization (WHO) lowered their guideline to 100 becquerels per cubic metre in 2007 but Canada has not followed suit, despite experts calling on Health Canada to do so.
Health Canada officials have previously told the IJB that while the federal safety guideline undergoes ongoing review, the current threshold reflects the country’s high level of naturally occurring radon. There are no immediate plans to adjust it, they say.
The only way to know the amount of radon in one’s home is to test for it. Canadians who find high levels of radon in their homes may hire a trained professional to mitigate the risk in their home.
FACTBOX:
Source: Cross-Canada Survey of Radon Exposure in the Residential Buildings of Urban and Rural Communities
According to the new study:
- One in five Canadian residential buildings are at or above 200 Bq/m³
- One in three Atlantic properties are at or above 200 Bq/m³
- One in six Central properties are at or above 200 Bq/m³
- One in five Prairie and NT properties are at or above 200 Bq/m³
- One in three Pacific Interior and YT properties are at or above 200 Bq/m³
- One in 75 Pacific Coastal Canadian properties are at or above 200 Bq/m³