Radon (Rn) is a naturally occurring, colourless and odourless gas that is radioactive and known to cause lung cancer. In fact, Rn is the second leading cause of lung cancer after smoking and the leading cause of the disease among non-smokers (World Health Organization, 2009). Radon is generated naturally from the radioactive decay of uranium. Both elements are found in varying amounts in all the soils and rocks throughout the province (Goodwin et al., 2009, 2010a). Since Rn is a gas, it is easily transported in the natural environment and transfers readily into air and water. In the outdoor environment, Rn emanating from the earth is very quickly diluted in the air to very low (background) concentrations (Goodwin et al., 2010b) that are well below the level of 200 Bq/m3 that is deemed a health risk by Health Canada (Health Canada, 2008). Although a gas, Rn is very heavy, heavier than lead, in fact, and in the enclosed spaces of an indoor environment (homes and buildings) Rn can concentrate in low-lying areas like the basement or lowest levels of the home. Radon in indoor air can sometimes reach high enough levels to be a health risk and exceed the 200 Bq/m3 Health Canada guideline.

Health Canada has established a protocol for Rn testing of homes (Health Canada, 2008). The protocol states that a home exceeding the 200 Bq/m3 guideline, but below 600 Bq/m3, should be remediated to below the guideline level within two years. Homes with a Rn level greater than 600 Bq/m3 should be remediated to below the guideline within one year. There is an abundance of information available regarding Rn testing of homes and the remediation of homes that are found to exceed the Health Canada guideline. Readers may begin their search with the Nova Scotia Environment (https://novascotia.ca/nse/environmental-health/radon.asp) and Health Canada (https://www.canada.ca/en/health-canada/services/health-risks-safety/radiation/radon/resources.html ) websites.

The Nova Scotia Department of Health and Wellness recommends that all homeowners in the province test their homes for Rn. Many Rn studies carried out globally have shown conclusively that, although the percentage of homes exceeding established Rn guidelines can vary from area to area, there are no areas completely devoid of homes with high Rn. No matter where you live, the only way you will know for sure whether or not your home has high Rn is to complete a proper Rn test (Health Canada, 2008). Since there are regions where there are a higher percentage of Rn guideline exceedences, a map such as this showing the distribution of these regions is useful in determining priority areas for testing and for assisting with building code guidelines. https://fletcher.novascotia.ca/DNRViewer/?viewer=Radon