![]() This guideline provides Canadians with guidance on when remedial action should be taken to reduce radon levels. The current Canadian guideline for radon in indoor air for dwellings is 200 becquerels per cubic metre (200 Bq/m 3). Reproduced with the permission of Natural Resources Canada 2008, courtesy of the Geological Survey of Canada 1.3 Radon GuidelineĪlthough there is currently no regulation that governs an acceptable level of radon in Canadian homes, Health Canada, in partnership with the provinces and territories, has developed a guideline. Radon levels are generally highest in basements and crawl spaces because these areas are nearest to the source and are usually poorly ventilated. When radon is confined to enclosed or poorly ventilated spaces, it can accumulate to high levels. However, if a building is built over bedrock or soil that contains uranium, radon gas can be released into the building through cracks in foundation walls and in floor slabs, construction joints, gaps around service pipes and support posts, floor drains and sumps, cavities inside walls, and the water supplies. When radon escapes from the bedrock into the outdoor air, it is diluted to such low concentrations that it poses a negligible threat to health. Because radon is a gas, it can move freely through the soil enabling it to escape to the atmosphere or seep into buildings. This is a diagram of radon movement indoors as well as outdoors. Results indicate that approximately 7% of Canadians are living in homes with radon levels above the current radon guideline of 200 Bq/m 3, and that no areas of Canada are radon free. Long-term (≥3 months) measurements were conducted during the heating season in all geographic areas of Canada. The source of most radon in houses is the soil on which the house is standing, and for that reason higher indoor radon levels are more likely to exist in the lower levels of the house.įrom 2009 to 2011, Health Canada conducted a cross-Canada residential radon survey in order to characterize the distribution of indoor radon levels in Canada. While some amount of radon is expected to be found in any home across Canada, the only way to know how much radon is in a home is to test. The level of risk depends on the concentration of radon and duration of exposure. The only known health risk associated with long-term exposure to radon is an increased risk of developing lung cancer. While usually less of a concern, dissolved radon outgassing from water is another potential source of radon in air for homes with groundwater wells (refer to "Annex 4 - Radon from Water and Construction Materials" for more details). Figure 1 illustrates various radon entry routes. Radon can enter a home any place it finds an opening where the house contacts the soil: cracks in foundation walls and in floor slabs, construction joints, gaps around service pipes, support posts, window wells, floor drains, sumps or cavities inside walls. When radon enters an enclosed space, such as a home, it can accumulate to high concentrations and become a health concern. When radon escapes from the ground to the outdoors, it mixes with fresh air resulting in concentrations too low to be of concern. However, it can be detected easily with radon measurement devices. It cannot be detected by the senses i.e., you cannot see it, smell it, or taste it. Radon is a naturally occurring radioactive gas that is formed by the breakdown of uranium in soil, rock and water. There is also brief mention of some preventive measures now available for new home construction.Ī separate guide is available for assessing radon in public buildings, such as workplaces, schools, day cares, hospitals, care facilities, and correctional centres. The scope of this document is limited to guidance regarding types of measurement devices, device placement, measurement duration, and the interpretation of measurements. The purpose of the testing is to evaluate radon levels in order to determine the need for remedial action to protect the occupants. This document is intended for persons and organizations carrying out radon testing in residential homes. Annex 5 – Radon Preventive Measures in New Construction. ![]() Annex 4 – Radon from Water and Construction Materials.Annex 3 – Conditions for Short term testing.Annex 1 – Recommended Procedure for Testing Radon in Residential Dwellings (Homes). ![]()
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