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All About Radon

What is Radon?

Radon is a radioactive gas that is formed naturally by the breakdown of uranium in soil, rock and water. Radon is colourless, odourless and tasteless.

Click on the video above to find out more details about radon testing and mitigation with Mike Holmes.

When Radon is released from the ground outside it mixes with fresh air and gets diluted resulting in concentrations too low to be of concern. However, when Radon enters an enclosed space, such as a house or basement, it can accumulate to high concentrations and become a health risk.

How can Radon enter my home?

Radon gas can enter a house 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 and support posts, floor drains and sumps, cavities inside walls, and the water supply.

Radon can also be found in groundwater from private or small community wells. Radon produced in the ground can dissolve and accumulate in water from underground sources such as wells. When water containing Radon is agitated during daily household use – showering, clothes washing or cooking, for example – the Radon gas can be released into the air. However, research has shown that drinking water that contains Radon is far less harmful than breathing the gas. The health risk does not come from consuming the Radon, but from inhaling the gas. And in most cases, the risk of Radon entering the home through water is much lower than if it enters through the ground.

 radon sources

Materials used to construct a house – stones, bricks, cement, or granite, for example – are not a significant source of Radon in Canada. Natural materials taken from the ground, like granite, can contain some uranium and may have higher levels of radiation or Radon than expected, but in the vast majority of cases these levels are not significant. In February 2010, Health Canada completed a study of 33 types of granite commonly purchased in Canada and none were found to have significant levels of Radon.

Almost all homes have some Radon. The levels can vary dramatically even between similar homes located next to each other. The amount of Radon in a home will depend on many factors including:

    Soil Characteristics: Radon concentrations can vary enormously depending on the uranium content of the soil. As well, Radon flows more easily through some soils than others, for example sand versus clay.

    Construction Type: The type of home and its design affect the amount of contact with the soil and the number and size of entry points for Radon.

    Foundation Condition: Foundations with numerous cracks and openings have more potential entry points for Radon.

    Occupant Lifestyle: The use of exhaust fans, windows and fireplaces, for example, influences the pressure difference between the house and the soil. This pressure difference can draw radon indoors and influences the rate of exchange of outdoor and indoor air.

    Weather: Variations in weather (e.g., temperature, wind, barometric pressure, precipitation, etc.) can affect the amount of Radon that enters a home.

Because there are so many factors, it is not possible to predict the Radon level in a home; the only way to know for sure is to test.

With support from / Avec l'appui de
Health Canada / Sante Canada


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Questions about Radon?
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