According to the Cross-Canada Survey of Radon Exposure, roughly 18% of Canadian homes have levels higher than what is deemed safe. Some regions are more affected than others, with places like Manitoba, Saskatchewan, and New Brunswick seeing higher rates of the radioactive gas than places like Ontario, Quebec, and British Columbia.
Other factors contribute to whether a home has a higher radon level, including whether it is in a rural or urban community and the design of the building. Since radon is the second-leading cause of lung cancer in non-smokers, those at risk should know how to test for radon levels and how to reduce them if they're too high.