The Regional Municipality Of York

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Radon: Test Your Home

What is radon?

Radon is a colourless, odourless and tasteless radioactive gas. It is produced naturally in the environment when uranium in rock and soil breaks down. Radon gas released directly from the ground into the outdoor environment is diluted to low levels. Radon can enter a building anywhere there is an opening in contact with the soil. Radon gas can also enter a building through cracks and openings where the foundation is in contact with the soil. It can build up to high concentrations in poorly ventilated areas, like basements.

Radon gas is found at low levels in almost every home. It is estimated that 4.6 % of Ontarians live in homes with radon levels above the current Canadian radon guideline of 200 Bq/m3 (Source: Public Health Ontario)

Image of a home with radon entering from soil, fittings, foundation cracks and sump drain
Adapted with the permission from Natural Resources Canada 2008, courtesy of the Geological Survey of Canada.

Why is radon a health concern?

Radon gas can become a health risk if it is able to buildup to high levels. These risks do not come from immediate exposure, but from long-term exposure to high levels of radon.

Radon is the second leading cause of lung cancer, after smoking, and is responsible for almost 850 lung cancer deaths in Ontario each year (Source: Public Health Ontario). Exposure to radon does not produce any immediate symptoms, like coughing or headaches, so you may not realize you have been exposed. This is why it’s important to test your home for radon levels.

If you are a smoker and exposed to radon, your risk of lung cancer increases. Reducing your exposure to radon and other risk factors (e.g. smoking) will greatly reduce your risk. Learn more about taking the first step towards quitting smoking.

The York Region “Radon - Test Your Home” study

To gain a better understanding of radon levels in York Region, public health initiated a study in 2017 to assess radon levels in residential homes. Public health offered homeowners the opportunity to test radon levels in their homes for free, as part of the Radon - Test Your Home Study.

The purpose of the study was to:

  • Measure radon levels in residential homes across York Region
  • Better understand York Region residents knowledge and awareness of radon and the associated health risks
  • Increase awareness and inform residents about the risk of radon

Around 500 homeowners tested their homes for at least 91 days from fall 2017 to summer 2018. The majority of York Region homes had low levels of radon that were well below the Health Canada guideline. Find out more about the study results.

Testing for radon

While the study found low levels, it is still recommended to test your home to know what your risk may be. The only way to know if a home has an elevated level of radon is to test for it. To get an accurate measure of radon exposure, Health Canada recommends testing your home for a minimum of three months during the fall and winter months, when windows and doors are generally closed.

Radon test kits can be purchased for approximately $45 to $70 from a home improvement retailer, online or by contacting a certified radon measurement professional. Additional costs may be required for laboratory analysis.

Where to buy a test kit

Visit for more information on where you can purchase a test kit or hire a professional.

How to set up a test kit

Visit Health Canada’s Guide for Radon Measurements in Residential Dwellings (Homes) for more information on how to test your home.

What happens if my radon results are high?

The Canadian radon guideline is 200 Bq/m3. Health Canada recommends homes with radon levels between 200 and 600 Bq/m3 ;be fixed within two years; homes with radon levels above 600 Bq/m3 should be fixed within one year.
Homes with radon levels betweeen 200 and 600 becquerels per cubic metre should be fixed within 2 years and homes with radon levels above 600 should be fixed within 1 year
Source: © All rights reserved. How to Fix My Radon Problem? How Soon Should Radon Levels be Reduced? Health Canada, 2014. Reproduced with permission from the Minister of Health, 2016.

If your test results show elevated radon levels, consult with a certified radon mitigation specialist on what you can do to reduce levels in your home.

  • Contact the Canadian National Radon Proficiency Program (C-NRPP) at 1-855-722-6777 (email:, or the Canadian Association of Radon Scientists and Technologists (CARST) at for a certified mitigation specialist.

For more information on fixing your home to reduce radon, review Health Canada’s Radon - Reduction Guide for Canadians


For more information on radon, visit:

radon,radiation,air quality,radon testing The Regional Municipality of York en-US Illustration of a neighbourhood Radon: Test Your Home You can’t see, taste or smell radon but it is the second leading cause of lung cancer. Learn more about radon and the York Region study.

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