Topic Overview

What is radon?

Radon is a radioactive gas that causes cancer. Radon is found in rock, soil, water, some building materials, and natural gas. You can't see, taste, or smell it.

How does radon exposure occur?

Any home, school, office, or other building can have high levels of radon. Radon is found in new and old buildings. It can seep in through the foundation of a house built on radon-contaminated soil. Then the radon may get trapped inside the house. It sinks to the low points in buildings, so it often is found in basements. But a building can have high levels of radon even if it doesn't have a basement.

Radon is found in homes all over the world, including Canada. High radon levels are not widespread in Canadian homes.¹ If you are concerned about exposure to radon gas in your home, you might consider testing.

What are the health effects of radon exposure?

Over time, exposure to radon can cause lung cancer. It is estimated to cause about 1,500 to 2,000 lung cancer deaths per year in Canada.² People who smoke have an even higher risk of lung cancer from radon exposure than people who don't smoke.

How can you find and remove high levels of radon?

You can test for radon using a do-it-yourself test. Radon detectors can be hard to find in many parts of Canada. Contact your provincial environmental office for advice. You also can hire a qualified tester to do the test.

If you have questions about radon in your house, you can get help from the Canada Mortgage and Housing Corporation by calling 1-800-668-2642.

If tests find a high level of radon, you'll need to reduce it. There are two ways to do this:

• Prevent radon from entering the building.
• Vent radon out of the building.

Currently, Canada does not have a national program for certification of individuals or companies that provide radon testing and removal. Until a program is created, Health Canada recognizes the certification programs offered in the United States through the National Environmental Health Association or the National Radon Safety Board and encourages Canadians to use a tester that is certified by one of these programs.³

Frequently Asked Questions

Health Effects of Radon Exposure

When radon starts to decay, very tiny radioactive particles are released. If you inhale these particles, they enter the lungs and may cause cancerous changes in nearby cells. If you breathe in radon, you have a greater chance of getting lung cancer.⁶

Radon is the second leading cause of lung cancer, second only to tobacco smoke. It is estimated to cause between 1,500 to 2,000 deaths from lung cancer per year in Canada.¹

The combination of smoking and radon exposure can greatly increase your risk of developing lung cancer. If you smoke or live with someone who smokes and you live or work in a place with dangerous radon levels, your risk of lung cancer is significantly higher than for someone who has never smoked but lives or works in places with unsafe radon levels. It is never too late to reduce your risk of lung cancer. Don't wait to test for and fix a radon problem. And if you smoke, try to quit. For more information, see the topic Quitting Smoking.

Radon exposure does not produce immediate symptoms. You may not realize that you are being exposed to dangerous levels of radon until you or someone in your family is diagnosed with lung cancer.

What Increases Your Risk of Radon Exposure

When uranium decays, it releases radon. Since uranium occurs naturally in soil and rocks, radon is found all over the world. High radon levels are not widespread in Canadian homes.¹ If you live or work in an area that has large deposits of uranium you may be more likely to be exposed to high levels of radon. But things relating to the specific construction and location of your house may be just as likely to affect your risk of radon exposure as the source of the radon itself. Even houses right next to each other can have very different radon levels.

Radon enters a home or building through cracks in the foundation or walls, through basement floors, and in water supplies (such as private wells). If the water supply contains radon, it may enter the air in the home through faucets, showers, dishwashers, or washing machines. Radon may also enter the home through pipes, sumps, or drains.

Radon is also found in many building materials. But building materials rarely cause a radon problem all by themselves.

Radon is heavier than air, so it is often found in higher concentrations in lower levels of buildings, such as in basements and sumps. Because radon is odourless, tasteless, and invisible, it is wise to test your home and office for radon levels no matter where you live or work.

How to Test for Radon

Testing for radon can be done with a do-it-yourself home test. The two types of home tests used to detect radon are short-term and long-term.

Radon detectors can be hard to find in many parts of Canada. You may find radon detectors in some retail stores that sell building, hardware, or health care items, or you can order them online. Check your local or regional yellow pages for companies that may sell these products, or contact your local or provincial environmental office.

Currently, Canada does not have a national program for certification of individuals or companies that provide radon testing and removal. Until a program is created, Health Canada recognizes the certification programs offered in the United States through the National Environmental Health Association or the National Radon Safety Board and encourages Canadians to use a tester that is certified by one of these programs.³

• The short-term test kit stays in your home or office for 2 to 90 days. Radon levels vary daily and from season to season. So you may want to follow up the first short-term test with a second to determine whether reduction in radon is needed.
• The long-term test kit stays in the home or office for more than 90 days. A long-term test will give more accurate results because radon levels can fluctuate from season to season.

These tests work by measuring average indoor levels of radon in your home or office. Radon is measured in units of radioactivity per volume of air. The most common measure used in Canada is becquerels per cubic metre (Bq/m3). Health Canada recommends remedial measures when radon levels are higher than 200 Bq/m3 in the normal occupancy area of a dwelling.⁴

How to Prevent, Reduce, or Remove Radon

If your home or workplace has a high level of radon, you should take measures to reduce it. The goals of radon reduction are to:

• Prevent radon from entering the building.
• Vent or remove radon once it has entered the building.

The most common and usually most effective way to prevent radon from entering the home is through sub-slab depressurization, which involves venting air from beneath the foundation. Another way to remove radon-containing air from a building involves placing heavy plastic over the soil in earth-floored crawl spaces and using a fan and pipes or duct work to vent the radon to the outside (from under the plastic).

This technique needs to be performed by qualified contractors who have completed training in a national radon proficiency program. Currently, Canada does not have a national program for certification of individuals or companies that provide radon testing and removal. Until a program is created, Health Canada recognizes the certification programs offered in the United States through the National Environmental Health Association or the National Radon Safety Board and encourages Canadians to use a tester that is certified by one of these programs.³

The first step in reducing the level of radon in your home or office involves simple venting methods.

Methods of ventilation can include:⁵

• Opening windows. This usually reduces radon only for a short time. Radon levels most often return to previous values in less than a day once the windows are closed.
• Increasing air movement with ceiling fans.
• Suctioning the air from the soil under the house (soil suction method). This takes radon from the soil and vents it into the air above the house where it is diluted.
• Moving air through a crawl space with a fan.
• Blowing air into a basement to pressurize the room and prevent radon from seeping in.

The balance of air exchange is important to properly remove radon from the home or office. This is why it is essential to have a contractor properly trained in radon reduction to help with ventilation procedures.

Other control methods used to reduce radon include sealing cracks in the foundation or walls and using air cleaners.⁵

Once radon reduction or prevention procedures are done, the home or building should be retested. You may need to retest the home or building more than once until the radon level falls below the acceptable level of less than 200 Bq/m3. It is usually safe to continue living in the home or building while the radon is being vented, but you may want to confirm this with your local or provincial environmental office.

Helpful Resources

Check with your local or provincial environmental office for more information about radon exposure in your area and where you can find home radon test kits. These offices may also be able to help you find qualified contractors with experience and training in radon removal.

If you have questions about radon in your house, you can get help from the Canada Mortgage and Housing Corporation by calling 1-800-668-2642. For more resources, see the Other Places to Get Help section of this topic.

Most countries have agencies that provide information about environmental protection. Contact your local environmental agency for more information about radon exposure in your area.