Children's Health & Safety Association

Issue 43: July 2018

Saturday, 30 November 2013 11:47

What is Radon? Feature Story

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November 15, 2013 – Radon is invisible, odourless, tasteless, and therefore undetectable. When radon is released from the ground into the outdoor air it is not a concern, however, when it is released in an enclosed space like the basement of a house, it can accumulate to high levels posing a health risk for you and your family.

No longer are basements used for just storage and laundry. Today, basements are predominantly living spaces - a family room, a playroom for the children, an apartment, an office, exercise room and even a home daycare centre. If any of the above sounds familiar, do yourself a favour and read on. If your home does not have a basement and the ground floor is in contact with the earth, has a crawl space or is built slab-on grade - this article also concerns you.

What are the Health Risks?

When radon is inhaled into the lungs, it breaks down into radioactive elements and emits alpha particles that are absorbed by nearby lung tissue. This process can result in lung cell death or damage. The risk of developing lung cancer from radon depends on the concentration of radon in the air and the length of time of exposure.

Radon exposure is linked to roughly 16% of lung cancer deaths in Canada, and is the second leading cause of lung cancer after smoking.

For smokers, the combination of smoking and exposure to radon can significantly increase the risk of lung cancer. Radon exposure is linked to roughly 16% of lung cancer deaths in Canada, and is the second leading cause of lung cancer after smoking.

The World Health Organization (WHO) estimates that radon causes up to 15% of lung cancers worldwide. Radon is estimated to be responsible for approximately 3,000 lung cancer deaths every year in Canada and some 21,000 deaths in the US every year.

Recent studies by the WHO have confirmed that the lung cancer risk extends to radon levels well below the current standards in North America and Europe. Health Canada recommends that all homeowners test their homes for radon gas in the interest of their family's safety.

Other than lung cancer, there is no evidence that radon exposure causes other harmful health effects, i.e. other forms of cancer, respiratory diseases such as asthma, or symptoms of persistent coughing or headaches.

What are the Health Risks for Children?

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.

Jing Chen, Head of Radiological Impact Section of the Radiation Protection Bureau for Health Canada authored technical notes entitled, "Canadian Relative Risk from Radon Exposure for Short Periods in Childhood Compared to a Lifetime" that was published in the International Journal of Environmental Research and Public Health in May 2013.

Jing Chen states that if a child lived in a home with a very high radon concentration of 2,000 Bq/m3 for four years, the Lifetime Relative Risk (LRR) is equivalent to a lifetime radon exposure of 100 Bq/m3 and the risk is about 50% higher than the baseline, lung cancer risk of people that have never smoked.

radon2The equivalency of lifetime risk between short period with high exposure in childhood and lifetime constant exposure clearly supports the Canadian Radon Guideline recommendation that the higher the radon concentration, the sooner remedial measures should be undertaken.

There are large uncertainties associated with the estimate of risk that exposure to radon poses to children compared to adults and therefore no adjustment is made to the risk model for children’s sensitivity to radon until more data becomes available.

Jing Chen is a member of Canadian Radiation Protection Association, the editorial board of Radiation Protection Dosimetry, the editorial board of Radiation Environmental Biophysics, advisor to the United Nations Scientific Committee on the Effects of Atomic Radiation, the Radioactivity Expert Group, Arctic Monitoring and Assessment Programme (AMAP), and the Expert Group on Radiological Protection Science, OECD Nuclear Energy Agency's Committee on Radiation Protection and Public Health (CRPPH).

Studies Find Direct Evidence Linking Radon in Homes to Lung Cancer

A North American and European study completed in 2005 combined data from several previous residential studies and found definitive evidence of an association between residential radon exposure and lung cancer. These two studies go a step beyond earlier findings. They confirm the radon health risks predicted by occupational studies of underground miner’s who breathed radon for a period of years. Early in the debate about radon-related risks, some researchers questioned whether occupational studies could be used to calculate risks from exposure to radon in the home environment. “These findings effectively end any doubts about the risks to Americans of having radon in their homes,” said Tom Kelly, Former Director of EPA’s Indoor Environments Division. “We know that radon is a carcinogen. This research confirms that breathing low levels of radon can lead to lung cancer.”

All countries are affected to some degree by radon, but the problem is particularly common in Sweden, other Nordic countries, Germany and the USA.

How does radon enter a house?

Radon can get into a house any place it is in contact with the ground, regardless if you have a basement, a crawl space or if your home is built slab-on grade.

redon-5070(Image on left: © Department of Natural Resources Canada.  All rights reserved) Radon is a radioactive gas that occurs naturally when the uranium in soil and rock breaks down. Air pressure inside your home is usually lower than in the soil surrounding the foundation of your home. Things like the use of air exchangers, exhaust fans and clothes dryers cause the difference in pressure. When air is pushed out of the house, outside air is pulled back in to replace it and much of the replacement air comes from the ground surrounding the house bringing gases such as radon with it. Radon enters your home any place it finds an opening where your home contacts the soil, such as:


  • cracks in the foundation walls and in floor
  • dirt floors
  • construction joints
  • gaps around service pipes
  • support posts
  • window casements
  • floor drains
  • sumps, and
  • cavities inside walls

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 radon in water is agitated by daily household use it escapes from the water and goes into the air. Health risks are not from ingestion but from radon inhalation.

Radon concentrations fluctuate seasonally, but are usually higher in winter than in summer, and are usually higher at night than during the day because the sealing of buildings (to conserve energy) and the closing of doors and windows (at bedtime), reduces the intake of outdoor air and allows the build-up of radon.

Radon Levels in Canada

redon-2729Concentrations of radon are usually higher in areas where there is a greater amount of uranium in underlying rock and soil. Almost every home in Canada has some amount of radon and levels will vary from one home to another even if they are next door to each other. A small percentage of homes will have radon levels above the guideline and the ONLY way to be sure is to perform a test.

The current Canadian guideline for radon in indoor air for homes is 200 Becquerels per cubic metre (200 Bq/m3) which was reduced from 800 Bq/m3 based on new information about potential health risks. The becquerel is the unit scientists use to measure the number of radioactive decays of radon atoms. One becquerel corresponds to one disintegration per second.

Health Canada's previous guideline has been in place since 1988. The original guideline was based on estimates of lung cancer risk from studies of underground uranium miners exposed to very high levels of radon. Uncertainty existed with the projection of lung cancer risk from occupational radon exposure to the public for residential exposures.

redon-9470Recent scientific studies have conclusively linked the risk of developing lung cancer to levels of radon found in some houses. 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. The new guideline of 200 Bq/m³ makes Canada's guidelines lower than or equal to most every other major industrialized country.

While the international community uses the Becquerel per cubic meter of air (Bq/³) measurement, the USA uses the picocurie per litre to measure radon. One pCi/L is equivalent to 37 Bq/m³.

Health Canada's National Radon Program conducted a two-year cross-Canada survey of 14,000 homes in 2009 and 2010. The participants were recruited by Prairie Research Associates (PRA) and underwent a three-month radon test during the winter and fall seasons. Results showed that:

  • About 7% of homes in Canada have radon levels above the Canadian guideline.
  • Radon levels vary quite significantly across the country.

The objective of this study is:

  • To obtain an estimate of the proportion of the Canadian population living in homes with radon gas levels above the guideline of 200 Bq/m3,
  • To identify previously unknown areas where radon gas exposure may constitute a health risk, and,
  • Over time, build a map of indoor radon gas exposure levels across Canada.

This survey confirmed that radon levels varied significantly across the country and that there are areas where high levels of indoor radon are more prevalent.

  • Manitoba, New Brunswick, Saskatchewan, and the Yukon had the highest percentages of participant homes which tested above the radon guideline.
  • Nunavut and Prince Edward Island had the lowest percentages.
  • Of the 121 Health Regions tested, there were 14 Health Regions where the raw percentage of homes tested above the guideline ranged from 23 to 44%. Five of these were in Manitoba, four in New Brunswick, three in Saskatchewan, and one each in Quebec and British Columbia.
  • There were another nine Health Regions where the raw percentage of homes above the radon guideline ranged from 16 to 21%.
  • Fifty-four (45%) of the Health Regions had 10% or more homes above the guideline level.

The results of this study show that even for those provinces where the overall results indicate a lower incidence of homes with elevated radon levels, there were still areas of those provinces with high radon levels and a significant number of homes with radon concentrations above the guideline. In Ontario, where the population-weighted estimate was 4.6% of homes exceeding the guideline, 13 of 36 Health Regions had more than 10% of the homes test above the guideline.

World Health Organization Launches International Radon Project

In an effort to reduce the rate of lung cancer around the world, the WHO launched an international radon project to help countries increase awareness, collect data and encourage action to reduce radon-related risks. The U.S. Environmental Protection Agency is one of several government agencies and countries supporting this initiative and is encouraged by WHO’s attention to this important public health issue.

"Radon poses an easily reducible health risk to populations all over the world, but has not up to now received widespread attention," said Dr. Michael Repacholi, coordinator of WHO’s Radiation and Environmental Health Unit. He went on to say that "radon in our homes is the main source of exposure to ionizing radiation, and accounts for 50% of the public’s exposure to naturally-occurring sources of radiation in many countries."

How Can You Reduce the Level of Radon in Your Home?

redon-2429You can reduce the level of Becquerels of radon by using methods that are affordable, practical and with regular maintenance, may in fact protect the value of your home. If the radon level in your home is above the allowable 200 Bq/m3, you can take the following steps to reduce the level:

  • Ventilate the basement sub-flooring by installing a small pump that will draw the radon from below the concrete slab to the outside before it can enter your home (commonly known as Sub Slab Depressurisation and typically performed by a Contractor).
  • Increase the mechanical ventilation via a Heat Recovery Ventilator (HRV) to allow an exchange of air.
  • Seal all cracks and openings in foundation walls and floors, and around pipes and drains.
  • The cost for radon reduction are typically from $500.00 to $3,000.00 depending on the size and design of a home and the work that his required.

The standard method for reducing radon in a home is called 'active soil depressurization', which is usually completed by a contractor. A pipe is installed through the foundation floor and is connected to the outside. A fan attached to the pipe draws radon from under the home, before it gets inside, and releases it outside, where it is diluted.

redon-8710Radon professionals can help you determine the best way to reduce the radon level in your home. To find a certified radon professional in Canada go to the Canadian National Radon Proficiency Program (C-NRPP) or call 1-800-269-4174 (toll free).

In 2010, new National Building Codes were introduced to protect people against radon. These new codes require new homes to have a vapour barrier to reduce the entry of radon. They also require a 'rough-in' for a radon reduction system, which will significantly lower costs if action has to be taken later to reduce radon levels in the home.

How Do You Test Your Home for Radon?

You can test your home for radon by purchasing a do-it-yourself kit or by hiring a certified radon mitigation professional from an accredited organization that will conduct a long-term test for a minimum of three months.

All measurements should be made in the lowest level of the house (usually the basement), that is used or occupied for more than four hours per day. For some people the lowest level of the house is the ground level of the house. 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 house, the lowest level bedrooms or other areas such as a playroom are preferred.

The two most common types of radon detectors used for testing houses are short term and long-term detectors. The short-term detectors are used for a period of 2-7 days and the long-term detectors can be used for a period of 1 to 12 months. Since the radon concentration inside a house varies over time, measurements gathered over a longer period of time will give a more accurate indication of the radon level in a house. Health Canada recommends that houses be tested for a minimum of 3 months, ideally between September and April when windows and doors are typically kept closed. Long-term radon detectors commonly used are:

If you intend on conducting the radon test yourself read the manufacturer's instructions and follow the guidelines listed below when placing a radon detector in your home:

  • Make the measurement in the lowest lived-in area of your home where you or family members spend four or more hours per day.
  • redon-9648Avoid taking measurements in the kitchen. The exhaust fan as well as humidity and airborne particles from cooking may affect the accuracy of some types of radon detectors. Avoid taking measurements in the washroom as well because little time is spent there.
  • Place the detector where it will not be disturbed during the measurement period and avoid small-enclosed areas, such as a cupboard or closet.
  • Do not place the detector close to an outside wall or near a sump or floor drain.
  • Avoid placing the detector in drafts from heating or air conditioning vents, near windows or doors, or sources of heat, such as stoves, fireplaces or strong sunlight.
  • Place the detector a minimum of 50cm from any floor, wall or ceiling and more than 20cm from all other objects.

Where Can You Purchase a Radon Test Kit?

Radon test kits are relatively simple to use and can be purchased over the phone, on the internet or from home improvement retailers across Canada. The radon test kit includes instructions on how to set up the test and how to send it back to a lab for analysis once the testing period is over. The kits range from $25.00 to $75.00. For more information on do-it-yourself radon test kits, contact Health Canada's Radiation Protection Bureau at This email address is being protected from spambots. You need JavaScript enabled to view it. or 613-946-6384.

Health Canada recognizes the certified Canadian National Radon Proficiency Program (C-NRPP), offered through the American Association of Radon Scientists and Technologists (AARST).

Where Can You Find a Contractor for Radon Mitigation?

If you:

  1. plan to build a new house or add an extension to your house,
  2. are renting your present house or apartment, and
  3. have concerns at your workplace please click on Radon Frequently Asked Questions

redon-6192The Canadian Association of Research Scientists and Technologists (CARST)isa Canadian association dedicated to helping Canadians understand and reduce radon gas exposure in their homes and workplaces. Their ultimate goal is to:

  • Promote public awareness of radon measurement, radon mitigation and new construction radon reduction techniques.
  • Ensure quality standards are developed and adopted in radon measurement, radon mitigation and in construction of new radon reduction techniques.
  • Provide a community for education, sharing of ideas, resources and research.
  • Provide an effective partnership between radon professionals in the field and other interested public and private organizations such as Health Canada and the Canada Mortgage and Housing Corporation.


The Conference of Radiation Control Program Directors, Inc. (CRCPD), an American Association of Radon Scientists & Technologists, Inc. (AARST) and EPA's Radon program launched the Radon Leaders Saving Lives Campaign in 2008, with the goal of doubling the number of lives saved from radon-induced lung cancer within 5 years. The online platform www.RadonLeaders.org connects radon stakeholders through interactive tools (e.g. blogs and discussion forums), and features information like the Resource Bank and Radon Change Package to help facilitate action and radon risk reduction.

A Note of Gratitude

A big 'thank you' goes out to Sara Lauer, Media Relations Officer for the Communications and Public Affairs Branch with Health Canada for providing us with integral and informative resource material.


Canadian National Environmental Health Association National Radon Proficiency Program

Health Canada – or call 1-800-622-6232

The Lung Association – Antonella's Story – Brampton, Ontario – 2013

The Canadian Association of Research Scientists and Technologists (CARST) – includes Federal Government Agencies contact information for every province and territory, Radon video, a guide for Professional Contractors, and a guide for Canadian Homeowners.

The United States Environmental Protection Agency – Abundance of information including statistics and projections

World Health Organization - Ionizing Radiation, the International Radon Project, Handbook on Indoor Radiation

U. K. Radon - Public Health England

IRSN – Institut de Radioprotection et de Sûreté Nucléaire

International Journal of Environmental Research and Public Health

Radon Videos

  1. Reducing Radon in your home http://www.hc-sc.gc.ca/ahc-asc/media/video/reducing-radon-reduire-eng.php
  2. Radon Testing - The only way to know! - http://www.hc-sc.gc.ca/ahc-asc/media/video/radon-test-eng.php
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