Radon is a naturally occurring, colourless and odourless radioactive gas. It comes from the decay of uranium, which is found in rock and soil. Radon can enter buildings through cracks in the foundation floor and walls as well as other pathways such as construction joints, gaps around service pipes, floor drains, and sumps. In poorly-ventilated spaces radon can build up to potentially unsafe levels, increasing the risk of lung cancer. Radon is the leading cause of lung cancer in non-smokers and the second leading cause of lung cancer in smokers [Health Canada, Canadian Cancer Society].
Given the breadth of buildings where people live, work and play, a wide range of laws and policies may directly or indirectly apply to radon. This includes federal and provincial/territorial regulations, building codes, municipal by-laws, new home warranty programs and third party building certification programs. Some of these require air testing for radon, to be compared to their cited concentration limits. Others require new construction rough-ins for future radon mitigation measures or may require installation of mitigation systems when concentrations exceed specified limits. Health Canada’s guideline for radon is 200 becquerels per cubic metre (Bq/m3). When indoor air concentrations are found to exceed this level, corrective actions are recommended to be taken.