Radon
The Issue
Exposure to high levels of radon increases the risk of developing lung cancer. This correlation has prompted concern that radon levels in some Canadian homes may pose a health risk.
Background
Radon is a colourless, odourless, radioactive gas that occurs naturally in the environment. It comes from the natural breakdown of uranium, and can be found in high concentrations where soils and rocks contain uranium, granite, shale, or phosphate. Radon can also be found in soils contaminated with certain types of industrial wastes, such as the by-products of uranium or phosphate mining.
The Health Effects of Radon
In the open air, the amount of radon gas is so minimal that it does not pose a health risk. However, in confined spaces like mines radon gas can accumulate in relatively high levels and can become a health hazard. The only known health effect associated with exposure to high levels of radon is an increased risk of developing lung cancer.
Because it is radioactive, radon decays. As it decays, it produces decay products, sometimes called "radon daughters" or "radon progeny." Two of these progeny, polonium-218 and polonium-214, decay rapidly themselves, and emit alpha particles. When alpha particles hit an object, the energy in them is absorbed by the surface of the object. Human skin is thick enough not to be affected, but if you breathe in alpha particles, they can damage bronchial and lung tissue, and can lead to lung cancer.
In the 1970s, studies of the incidence of lung cancer in Canada among uranium miners showed a correlation between radon exposure and deaths from lung cancer. Although there is no evidence proving a direct link between radon levels in the home and lung cancer, Health Canada scientists have indicated that elevated levels of radon in the home could also pose a risk.
Radon in the Home
Radon gas can move through small spaces in the soil and rock upon which a house is built. It can seep into a home through dirt floors, cracks in concrete walls and floors, sumps, joints, basement drains, under the furnace base, and jack posts if the base is buried in the floor. Concrete-block walls are particularly porous to radon, and radon trapped in water from wells can be released into the air when the water is used.
A survey conducted by Health Canada in the 1970s showed that radon levels in certain Canadian cities were higher than in others. However, these same studies showed that it is impossible to predict whether any one house will have a high level of radon. Factors such as the location of the house and its relation to the prevailing wind may be just as important as the source of the radon.
Measuring Radon Levels in the Home
Commercial services are available to homeowners who wish to measure radon levels in their homes. Radon is measured in units called "becquerels per cubic metre." The most popular radon detectors are the charcoal canister and the alpha track detector. Both of these devices are exposed to the air in a home for a specified period of time, and then sent to a laboratory for analysis. There are other techniques for testing radon levels, but they require a trained operator and are more expensive.
Minimizing Your Risk
Health Canada's studies show that radon pollution is not widespread in Canadian homes. However it is difficult to predict the level in any one home. If you are concerned about exposure to radon gas in your home, you might consider testing the levels, and/or taking the following steps to reduce radon levels
- Renovate existing basement floors, particularly earth floors
- Seal cracks and openings in walls and floors, and around pipes and drains
- Ventilate the sub-floor of basement floors
Health Canada's Role
Health Canada has taken a number of steps to minimize the health effects of radon exposure. These include evaluating measurement techniques, developing guidelines and conducting research into all aspects of radon gas.
Although provincial and territorial governments have jurisdiction over the health effects of background radiation, Health Canada has recommended that the guideline for exposure to radon gas should be 800 becquerels per cubic metre as the annual average concentration in a normal living area. The guideline is an upper limit, and Health Canada recommends taking action to reduce radon levels in your home if they exceed the limit. Because there is some risk at any level of radon exposure, homeowners may want to reduce their exposure to radon, regardless of levels.
Recent scientific evidence and advances is bringing about a review of the current radon guideline in a normal living area. A federal-provincial working group and Health Canada are currently assessing a lower radon guideline level. Provincial and territorial partners are responsible for the implementation of the guideline.
Need More Info?
Health Canada and the Canada Mortgage and Housing Corporation have produced a booklet called  Radon - A Guide for Canadian Homeowners or call 1-800-668-2642.
To obtain information on how to access to charcoal canisters and the alpha track detectors to test for radon level please check your local Yellow Pages for "Home Inspectors".
For more information on occupational concerns go to The Canadian Centre for Occupational Health and Safety - What is Radon.
For additional information see the following Web sites:
For additional articles on this subject and other issues go to the It's Your Health Web site.
You can also call (613) 957-2991
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