Health Canada
www.hc-sc.gc.ca
Common menu bar links
Radon Frequently Asked Questions
Did you know?
Protecting your family's health from the risk of radon exposure starts with learning more.
- What is radon?
- What is the Canadian guideline for radon in indoor air?
- Why has Health Canada announced in June 2007 a lowering of the guidelines for acceptable levels of radon in the home from 800 to 200 Bq/m³?
- How can radon affect my health?
- I am a smoker. Does radon affect me more than a non-smoker?
- Are children more at risk from radon than adults?
- What about drinking water that contains radon?
- Where in Canada are radon levels the highest?
- How can radon get into my home?
- How do I test my home for radon?
- Where in the building should I perform the test?
- How can I reduce the amount of radon in my home?
- What is the difference between Bq/m³ and pCi/L?
- How much will it cost to mitigate my home?
- Where can I find a contractor for radon testing and mitigation?
- I am building a new house, can I have the site tested for radon?
- I don't have a basement. Do I still need to test my home for radon?
- My house is new (old) so it shouldn't have a problem, right?
- I am extending my house. Is there anything I can do to prevent radon entry into the extension?
- I am renting a house (apartment) and am concerned about radon. Is my landlord required to test for radon if I ask him to do so?
- I tested my rental home (apartment) and the radon reading was high, is my landlord required to fix this problem?
- As an employer, do I need to test for radon in the workplace?
- Are the radon detectors themselves dangerous or do they contain toxic substances?
- Where can I learn more?
A. Radon is a radioactive gas that is formed naturally by the radioactive breakdown of uranium in soil, rock and water. Radon also breaks down further to form additional radioactive particles called radon daughters, or "progeny". Radon is slowly released from the ground, water, and some building materials that contain very small amounts of uranium, such as concrete, bricks, tiles and gyproc. Radon cannot be detected by the senses, i.e., it is colourless, odourless and tasteless; however, it can be detected with special instruments.
When radon escapes from the ground into outdoor air it mixes with fresh air resulting in concentrations too low to be of concern. However, when radon enters an enclosed space, such as a building, it can accumulate to high concentrations.
Because the source of most radon in homes is the soil on which the house or building is standing and radon which escapes from the soil infiltrates a home through various pathways, higher indoor radon levels are more likely to exist where there is a direct contact with soil.
Radon concentrations fluctuate seasonally, but are usually higher in winter than in summer, and are usually higher at night than during the day. This is because the sealing of buildings (to conserve energy) and the closing of doors and windows (at bedtime), reduce the intake of outdoor air and allow the build-up of radon.
Q. What is the Canadian guideline for radon in indoor air?
A. The Canadian guideline for radon in indoor air for dwellings, which provides Canadians with guidance on when remedial action should be taken to reduce radon levels, is as follows:
"Remedial measures should be undertaken in a dwelling whenever the average annual radon concentration exceeds 200 becquerels per cubic metre (200 Bq/m³) in the normal occupancy area. The higher the radon concentration, the sooner remedial measures should be undertaken. When remedial action is taken, the radon levels should be reduced to a value as low as practicable. The construction of new dwellings should employ techniques that will minimize radon entry and will facilitate post-construction radon removal, should this subsequently prove necessary."
The becquerel is a unit of radioactivity. One becquerel corresponds to one disintegration per second.
Q. Why has Health Canada announced in June 2007 a lowering of the guidelines for acceptable levels of radon in the home from 800 to 200 Bq/m³?
A. Previously our estimates of lung cancer risk from radon were based on studies of underground uranium miners exposed to high levels of radon. Uncertainty existed with the projection of lung cancer risk from occupational radon exposure to the public for residential exposures.
Health Canada's previous guideline had been in place since 1988. Recent scientific studies have conclusively linked the risk of developing lung cancer to levels of radon found in some homes. These studies prompted the federal government to collaborate with provincial and territorial governments to review the federal radon guidelines in 2005. Following a risk assessment and a public consultation, the revised guideline was approved by the Federal Provincial Territorial Radiation Protection Committee in October 2006. Our new guideline of 200 Bq/m³ makes Canada better than or equal to most every other major industrialized country.
Q. How can radon affect my health?
Radon gas and radon progeny in the air can be breathed into the lungs where they breakdown further and emit "alpha particles". Alpha particles release small bursts of energy which are absorbed by nearby lung tissue. This results in lung cell death or damage. When lung cells are damaged, they have the potential to result in cancer when they reproduce.
The only known health risk associated with exposure to high levels of radon in indoor air is an increased lifetime risk of developing lung cancer. The effects depend on the levels of radon and how long a person is exposed to these levels.
On average, 10% of lung cancers are attributable to radon exposure worldwide. In 2006, an estimated 1,900 lung cancer deaths in Canada were due to radon exposure.
Other than lung cancer, there is no evidence that radon exposure causes other harmful health effects such as any other form of cancer, respiratory diseases such as asthma, or symptoms such as persistent coughing or headaches.
Q. I am a smoker. Does radon affect me more than a non-smoker?
A. Yes. The radon risk for a smoker (including those exposed to second hand smoke) is much greater than for a non-smoker. For example, if you are a lifelong smoker but are not exposed to radon, your risk of getting lung cancer is one in eight. If you add exposure to a high level of radon, your risk becomes one in three. On the other hand, if you are a non-smoker, your lifetime lung cancer risk at the same high radon level is only one in twenty.
Q. Are children more at risk from radon than adults?
A. Children have been reported to be at greater risk than adults for certain types of radiation exposure, but there is currently no conclusive data on whether children are at greater risk than adults from radon.
Q. What about drinking water that contains radon?
A. Research has shown that drinking water that contains radon is far less harmful than breathing radon. When the ground produces radon, it can dissolve and accumulate in water from underground sources, such as wells. When water that contains radon is agitated when used for daily household requirements radon gas escapes from the water and goes into the air. The health risk is not one of radon ingestion but of radon inhalation.
Q. Where in Canada are radon levels the highest?
A. Radon concentrations differ greatly throughout Canada but are usually higher in areas where there is a high concentration of uranium in underlying rock and soil. Radon is found in almost every home, but concentration levels will vary from one house to another, even if they are similar and next door to each other.
Q. How can radon get into my home?
A. The air pressure inside your home is usually lower than in the soil surrounding the foundation. This difference in pressure draws air and other gases, including radon, from the soil into your home.
Radon can enter a home 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.
The only way to find out if your home has a radon problem is to measure the radon concentration inside it.
Q. How do I test my home for radon?
A. There are several methods that can be used to test a dwelling for radon. There are radon detectors available that measure radon levels for short periods of time, and others that can gather data over many months. Since the radon concentration inside a home varies over time, measurements gathered over a longer period of time are generally considered to give a more accurate picture of the radon exposure. We recommend that homes be tested for a minimum of 3 months, ideally during the winter months as the radon concentrations are usually representative at this time.
Here are the detection methods currently recognized by Health Canada as acceptable for measuring radon in homes and public buildings.
Devices for Long-Term Measurements:
- Alpha Track Detection
- Electret Ion Chamber
Devices for Short-Term Measurements:
- Activated Charcoal Adsorption
- Charcoal Liquid Scintillation
- Electret Ion Chamber
- Continuous Radon Monitoring
- Continuous Working Level Monitoring.
A Guide for Radon Measurements in Residential Dwellings (Homes) is available should you require guidance regarding types of measurement devices, device placement, measurement duration, and the interpretation of measurement results in homes. A separate guide is also available for assessing radon in residential public buildings, such as hospitals, schools and long-term care facilities.
Q. Where in the building should I perform the test?
A. To provide a realistic estimate of the radon exposure of the occupants, all measurements should be made in the normal occupancy area of the lowest lived-in level of the home. The normal occupancy area is defined as any area occupied by an individual for more than 4 hours per day.
Potential measurement locations include family rooms, living rooms, dens, playrooms and bedrooms. A lower level bedroom is preferred because people generally spend more time in their bedrooms than in any other room in the house. Similarly, if there are children in the home, lowest level bedrooms or other areas such as a playroom are preferred.
Q. How can I reduce the amount of radon in my home?
A. If your radon test is above the guideline of 200 Bq/m³, you can take the following steps to reduce your risk:
- Increase the ventilation in the basement to allow an exchange of air
- Seal all cracks and openings in foundation walls and floors, and around pipes and drains
- Paint basement floors and foundation walls with two coats of paint and a sealant
- Ventilate the basement sub-flooring by installing a small pump to draw the radon from below the concrete slab to the outside before it can enter your home
- Renovate existing basement floors, particularly earth floors.
Mitigation, if needed, should be done by an experienced contractor. As with any contract, caution is recommended since contracts are legally binding. Therefore, you should ask if the contractor has the necessary certification from an accredited organization. As part of its certification program for radon, Health Canada is developing certification requirements for radon mitigation companies. Again, in the interim, Health Canada recognizes the certification programs offered by 
National Environmental Health Association (NEHA) or the National Radon Safety Board (NRSB). Individuals holding the Residential Mitigation Provider certification from these bodies will have demonstrated knowledge of radon mitigation techniques. Also, the contractor should be able to provide references which will attest client satisfaction with workmanship and costs.
Q. What is the difference between Bq/m³ and pCi/L?
A. The concentration of radon in air is measured in units of becquerels per cubic meter (Bq/m³) or picocuries per litre (pCi/L). Both these units are measurements of radioactive concentration. The international community uses the becquerel per cubic meter of air (Bq/m³), while the USA uses the picocurie per litre to measure radon. One pCi/L is equivalent to 37 Bq/m³.
Q. How much will it cost to mitigate my home?
A. The cost of reducing radon in your home depends on how your home was built and the extent of the radon problem. Most homes can be fixed for about the same cost as other common home repairs. The average radon remediation process, typically done using a contractor, will cost between $1500 - $3000. The cost is much less if a passive system was installed during construction.
Q. Where can I find a contractor for radon testing and mitigation?
A. The Canadian Radiation Protection Association (CRPA) provides a list of Canadian companies that perform radon testing and mitigation work. This list is for information only and the link to this site does not represent an endorsement of these companies or individuals by Health Canada. Health Canada recommends you consult radon testing and mitigation companies that are certified by various organizations, such as the National Environmental Health Association-National Radon Proficiency Program (NEHA-NRPP) or the National Radon Safety Board (NRSB).
Q. I am building a new house, can I have the site tested for radon?
A. Soil testing for radon is not recommended for determining whether a house should be built radon-resistant. Although soil testing can be done, it cannot rule out the possibility that radon could be a problem in the house you build. Even if soil testing reveals low levels of radon gas in the soil, the amount of radon that may enter the finished house cannot be accurately predicted because one cannot predict the impact that the site preparation will have on introducing new radon pathways or the extent to which a vacuum will be produced by the house causing radon to be drawn inside.
Q. I don't have a basement. Do I still need to test my home for radon?
A. Radon can seep from soil anywhere around and under a home, regardless or whether your home has a basement, a crawl space or is built slab-on grade.
Q. My house is new (old) so it shouldn't have a problem, right?
A. The age of a home is not factor when it comes to whether excessive levels of radon are present in the dwelling.
Q. I am extending my house. Is there anything I can do to prevent radon entry into the extension?
A. Yes using the advice for new buildings found in the Canada Housing and Mortgage Corporation's Radon a Guide for Canadian Homeowners. Particular attention should be paid to the area joining the original house to the new extension.
Q. I am renting a house (apartment) and am concerned about radon. Is my landlord required to test for radon if I ask him to do so?
A. No, there is no legal requirement for a landlord to test a rental property, thus you will have to do it yourself unless you can persuade him/her to test.
Q. I tested my rental home (apartment) and the radon reading was high, is my landlord required to fix this problem?
A. No, there is no legal requirement for him/her to mitigate the radon level.
Q. As an employer, do I need to test for radon in the workplace?
A. Federal employees are governed by the Canada Labour Code (CLC) which requires the Government of Canada to ensure that its workers are not exposed to high levels of radon. Other workplaces are governed by the Naturally Occurring Radioactive Material Guidelines. There is no legal requirement for employers to test, however, the only way for an employer to know if they are compliant with the CLC or the NORM Guidelines is to test.
Q. Are the radon detectors themselves dangerous or do they contain toxic substances?
A. No. Radon detectors do not pose a health risk.
A. More information on radon can be found on the Web:
You may also obtain a copy of the booklet called Radon - A Guide for Canadian Homeowners produced by Health Canada and CMHC by calling 1-800-668-2642. To find out more about radon, please contact Health Canada's Radiation Protection Bureau at 613-954-6647or at radon@hc-sc.gc.ca.
