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What is radon?
Radon is a gas found naturally in the environment. It comes from the natural decay of uranium found in rocks and soil.
Outside, the amount of radon in the air is very small and poses no threat to health. Inside, however, it can be a different story. In some poorly ventilated spaces like basements, radon can accumulate and reach high levels.
Exposure to high levels of radon can be hazardous to your health.
How can radon affect health?
The only known health risk associated with radon inhalation is lung cancer. It is estimated that 10% of all lung cancers are related to radon exposure.
The risk of developing lung cancer because of radon depends on the concentration of radon in the air you breathe and how long you have been exposed to it.
It can take between 10 and 30 years for some people to develop lung cancer after exposure to radon.
The combination of inhaling radon gas and smoking significantly increases the risks of developing lung cancer. To reduce your risk of lung cancer, don't wait to fix a radon problem: if you are a smoker, stop smoking.
Occasional exposure to radon does not produce any symptoms, such as persistent coughing or headaches.
"Because radon is colourless, odourless, and tasteless, it is imperceptible to us."
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What is Health Canada's guideline for radon?
In 2007, in consideration of the evidence
of the link between radon residential levels and elevated lung cancer risk,
Health Canada has developed the current radon
guideline, recommending that corrective action be taken when the level of
radon in the home is found to exceed 200 becquerels per cubic metre.
How does radon get into your house?
The air pressure inside your home is usually lower than in the soil surrounding the foundation.
This difference in the two pressures draws air and other gases in the soil, including radon, into your home.
Radon can enter a house any place it finds an opening where the house contacts the soil: cracks in foundation walls and in floor slabs, around utility installations and support posts, floor drains and sumps, and floor/wall joints.
Radon can easily flow through concrete block walls.
Could I have radon in my house?
Because radon is colourless, odourless, and tasteless, it is imperceptible to us.
Radon is found in almost every home, but concentration levels vary greatly from one house to another, even if they are similar and next door to each other!
Indoor radon levels are not only affected by the soil composition under and around the house, but also by the ease with which radon enters the house due to foundations with cracks and openings, the use of exhaust fans and windows and the amount of contact with the soil.
Homes are more likely to have high levels of radon if:
- they are built on dry porous soil
- the building site was once a riverbed, a glacial outwash, or a slide area
However, it is also possible to have high levels of radon in some homes built in non-risk areas.
A house's age is not an indicator of the level of radon concentration inside. New houses can also have many openings that can allow radon to enter.
Variations in weather can also affect the amount of radon that enters a home. Temperature inside and outside, humidity and wind can cause radon levels to vary from day to day.
How can I find out if there is radon in my house?
Because there are so many factors involved, it is very difficult to predict the radon level in any home. The only way to find out if your house has a radon problem is to measure the radon concentration inside.
There are radon detectors on the market that measure radon levels for short periods of time, and others that can gather data over many months. Since the radon concentration inside a house varies over time,
measurements gathered over a longer period of time are generally considered to give a more accurate picture of the radon exposure.
How can I reduce the risk?
If you are concerned about exposure to radon in your home, you can measure radon levels, and
take steps to reduce the risk.
Follow these steps to reduce radon levels in your home:
- Ventilate the basement by opening the windows to let fresh air in, and to allow air from the house to escape.
- Seal cracks and openings in foundation walls and floors, as well as around ducts and drains.
- Paint basement floors and foundation walls with two coats of paint and a sealant.
- Renovate existing basement floors, particularly earth floors.
- Ventilate basement sub-flooring. To do this, a small pump is installed to draw the radon from below the concrete slab to the outside before it can enter the home.
The steps you take to reduce radon levels in your home may have other benefits: you often reduce mold problems caused by humidity, and by sealing cracks, you keep cold air out and lower your heating bill.
For more information about testing or reducing radon levels, you can contact the Canada Mortgage and Housing Corporation at 1-800-668-2642.
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This article was produced by the WHO-PAHO Collaborating Center on Environmental and Occupational Health Impact Assessment and Surveillance of the Centre hospitalier universitaire de Québec, the Canadian Health Network's affiliate responsible for 
