A naturally occurring, odourless, colourless radioactive gas that seeps into homes through cracks in the foundation, gaps around pipes, and other openings. Radon is the second leading cause of lung cancer after smoking. Health Canada recommends that all homes be tested, and action should be taken if levels exceed 200 Bq/m3. Radon levels vary by region and can differ between neighbouring homes.
Why It Matters
You can't see, smell, or taste radon, but long-term exposure at elevated levels is a serious health risk. Testing is inexpensive (around $30 to $50 for a DIY kit) and mitigation, if needed, typically costs $2,000 to $3,000. It's an easy, affordable step that too many buyers skip.
Real-World Example
A buyer purchases a home in Brampton and decides to test for radon before moving in. They place a long-term alpha track detector in the basement for 90 days during the winter heating season. The result comes back at 280 Bq/m3, above Health Canada's guideline of 200 Bq/m3. A radon mitigation company installs a sub-slab depressurization system for $2,500, which reduces the level to 45 Bq/m3. The system consists of a small fan and PVC pipe that vents radon gas from beneath the foundation slab to outside the home.
Ontario & GTA Context
Parts of the GTA, particularly areas with certain types of bedrock and glacial deposits, can have elevated radon levels. Health Canada recommends testing all homes regardless of location, as levels can vary significantly even between neighbouring properties. Ontario does not currently require radon testing for home sales, but the Canadian Real Estate Association recommends it. Long-term testing during the heating season provides the most accurate results.
How It Works in Practice
Consider radon testing as part of your due diligence, especially for homes with basements or lower-level living spaces. A DIY long-term test kit costs $30 to $50 and provides results in 90 days. Professional testing with continuous monitors costs $150 to $300 and provides faster results. If levels exceed 200 Bq/m3, mitigation is straightforward and effective.
Common Questions
Do I need to test for radon when buying a house in Ontario?▾
How much does radon mitigation cost in Ontario?▾
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