What Is Radon?
Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil and rock. It seeps upward through the ground and accumulates inside homes and buildings — especially in basements and lower floors where air exchange with the outside is limited.
Radon is colourless, odourless, and tasteless. It cannot be detected without a test. And over time, breathing elevated concentrations significantly increases your risk of lung cancer — making it the leading environmental cause of lung cancer in Canada after smoking.
Why Radon Matters in Canada
Canada has some of the highest residential radon levels of any country. Health Canada estimates that approximately 7% of Canadian homes have radon levels at or above the national guideline of 200 Bq/m³. Millions more fall in a range where ongoing monitoring is recommended.
Certain regions have higher radon potential due to local geology. Uranium-rich granite bedrock and disturbed soils create conditions where radon is more likely to concentrate. The Okanagan Valley and parts of British Columbia, Ontario, and Saskatchewan are known higher-risk areas.
How Does Radon Enter a Home?
Radon moves through soil and enters buildings through any opening between the ground and the interior:
- Cracks in foundation floors and walls
- Construction joints and cold seams
- Gaps around service pipes and conduit
- Open sump pits and floor drains
- Crawlspace floors and block wall cores
The lower air pressure inside a heated building draws radon-laden soil gas upward — like a slow, continuous vacuum. Tightly sealed homes can be more vulnerable because there is less dilution from fresh outdoor air.
Health Canada's Radon Guideline
Health Canada recommends taking action when long-term radon levels reach 200 Bq/m³ or higher.
| Level (Bq/m³) | What It Means | Recommended Action |
|---|---|---|
| Below 100 | Low concern | Retest every 2–5 years |
| 100–199 | Moderate | Consider retesting; monitor seasonally |
| 200–599 | Elevated | Mitigation recommended within 2 years |
| 600+ | High | Mitigation recommended within 1 year |
Note: The U.S. EPA action level is 4.0 pCi/L (≈ 148 Bq/m³). Some Canadian professionals recommend acting at 150 Bq/m³ based on accumulating health evidence.
What Should You Do?
- Test your home. Testing is the only way to know your radon level. A long-term alpha-track test kit (90 days) gives the most accurate result. Digital monitors provide faster readings. Shop test kits and monitors →
- Understand your results. Compare your reading to the Health Canada guideline above.
- If elevated, mitigate. An active sub-slab depressurization system is the most effective solution — reducing levels by 80–99% in most homes. Learn how mitigation works →
