While only testing can determine the actual concentration of radon in a home, geological maps can be used to give a visual indication of potential risk. Geological maps should not be used as a decision-making tool for radon mitigation, Health Canada recommends that all homes be tested.

Between 2009 and 2011, Health Canada conducted a survey of radon concentrations in homes across Canada. The study tested radon levels in 14,000 homes over three months. The results indicate that seven per cent of Canadians are living in homes with high radon levels. This survey confirmed that radon levels vary significantly across the country. High levels of indoor radon are more prevalent in some areas; in some provinces, 20 percent of homes had high radon levels. For the full survey report and results by province/territory and health region go to: http://www.hc-sc.gc.ca/ewh-semt/alt_formats/pdf/radiation/radon/survey- sondage-eng.pdf.