What is radon?
Radon is a colourless, odourless gas that is widely present in the earth's surface. It comes from the radioactive breakdown of uranium. Uranium occurs naturally and can be found in small amounts in the soil, water and air.
Radon seeps into a home from surrounding soil. It comes up through pores in the soil under homes and buildings through gaps and cracks in the foundation, concrete walls and floors, sumps, joints, basement drains and other openings. Unsafe levels of radon could accumulate in poorly ventilated homes and buildings.
Radon is usually not a problem outdoors as the air quickly dilutes it to lower levels. It sometimes contaminates well water.
What are the health effects of radon?
Radon is a radioactive gas and naturally breaks down to form decay products, called "radon daughters." These can be inhaled deep into the lungs and damage lung tissue.
Exposure to high levels of radon increases the risk of developing lung cancer. Your risk depends on the amount of time you are exposed to radon. Radon also increases the risk of lung cancer from smoking.
How do I know if I have radon in my home?
Since radon concentration varies from house to house even in the same area, the only way to find out if you have radon in your home is to test for it.
How can I get my home tested for radon?
There are two ways of getting your home tested for radon.
Radon levels may vary daily, weekly, or even seasonally, depending on the climate, indoor ventilation and heating systems used. The best time to measure radon levels in your home is during cold weather (e.g., October to April) when indoor radon levels are generally highest.
Health Canada recommends testing for a minimum of three months. Radon levels are usually higher in basements and other areas of the home that are in contact with soil.
- You can purchase a radon detector such as a charcoal canister, electret ion chamber (commercially known as E-PERM) or an alpha-track detector in some retail stores that sell building, hardware or health care products. They are also available online or by mail through companies that specialize in home improvement and radiation safety. You can leave these devices, also known as "passive monitors," in your home for a specific period of time and then send them to a laboratory for analysis. The cost of the test using these simple devices is about $50.
- You can contract a trained technician or a professional home inspector to test for radon levels in your home, though this may be more expensive. Consult your local Yellow Pages for home inspection services or radon testing services, or contact Health Canada for a list of service providers.
What levels of indoor radon are considered safe?
Radon concentration in air is measured in units of Becquerels (Bq). The new guideline from Health Canada recommends that the level of radon in the air in a home in a normal living area be no more than 200 Becquerels per cubic metre (Bq/m3) per year. Health Canada recommends:
Visit Health Canada's web site for more information on the Radon Guideline for Canada.
- Action should be taken to reduce radon levels in a home or building when the annual radon concentration exceeds 200 Bq/m3 in the normal occupancy area (the area of the home where residents spend more than 4 hours a day).
- Action should be taken sooner and within one year when the annual radon concentration reaches or exceeds 600 Bq/m3 and within two years if radon levels are between 200 Bq/m3 and 600 Bq/m3.
- Radon level should be reduced to a value as low as practicable.
- The construction of new homes and buildings should use techniques that will minimize radon entry.
How can I reduce the levels of radon in my home?
As with all other indoor air pollutants, the best way to reduce the levels of radon in your home is to control its source and ventilate:
If used along with these two recommended approaches, air filtration devices can also help lower the radon levels in a home.
- Reduce radon emission from the ground into your home by caulking and sealing cracks and holes in basement floors and walls. Painting the basement floor and wall surfaces may also help.
- If this is not possible or sufficient to reduce levels you can increase your ventilation, for example, by opening a window where fresh air can enter into your home.
Should I consider testing for radon if I am buying a home?
Testing of private homes for radon is currently not required during real estate transactions in Canada. However, if you are concern about the radon levels of a home that you are considering purchasing, you can always request that a thorough house inspection be conducted to include radon testing as a condition of your offer.
Where can I get more information?
Find out more about the health impact of radon, and tips on prevention and reduction.
Links to sites external to the Toronto Public Health Web site are provided as a convenience and their inclusion does not imply that Toronto Public Health endorses or accepts any responsibility for the content or use of these sites.
Last updated August 2009