Radon is measured in becquerels per cubic metre (Bq/m³) — a unit that describes how much radioactive decay is happening per second in a cubic metre of air. The higher the number, the more radon is present, and the greater your long-term health risk.
Understanding what these numbers mean — and what to do about them — is the first step to protecting your household.
Health Canada's Radon Guideline
Health Canada's current radon guideline is 200 Bq/m³. Any home testing above this level should undergo radon mitigation — ideally within one year of the test result.
Health Canada also recommends taking action at levels between 100–200 Bq/m³ where remediation is practical and cost-effective. Given that a standard sub-slab depressurization (SSD) system costs $1,500–$3,000 installed and reduces radon by 80–99%, it is almost always cost-effective.
Is There a "Safe" Level of Radon?
No. There is no threshold below which radon exposure carries zero risk. Radon causes lung cancer through the cumulative effect of alpha particle radiation on lung tissue over years of exposure. The lower your indoor radon level, the lower your lifetime risk — but some risk exists at every level above zero.
The World Health Organization (WHO) recommends a reference level of 100 Bq/m³ — half of Health Canada's action level — because the health evidence shows meaningful cancer risk well below 200 Bq/m³. Many Canadian mitigation professionals and health advocates argue that 100 Bq/m³ should be the Canadian action level as well.
Radon Level Reference Table
| Radon Level | Risk Category | Recommended Action |
|---|---|---|
| Below 100 Bq/m³ | Low | No immediate action required. Retest in 2–5 years or after major renovations. |
| 100–199 Bq/m³ | Moderate | Consider mitigation, especially if you spend significant time in lower levels of the home. |
| 200–599 Bq/m³ | Elevated | Mitigate within one year. Health Canada action level exceeded. |
| 600–999 Bq/m³ | High | Mitigate as soon as possible, ideally within a few months. |
| 1,000 Bq/m³ and above | Very High | Take immediate action. Avoid spending time in the lowest level until mitigated. |
What Is the Average Radon Level in Canadian Homes?
Health Canada's Cross-Canada Survey of Radon Concentrations in Homes (2012) found a national geometric mean of approximately 47 Bq/m³, but this average masks enormous regional variation. Saskatchewan and Alberta have provincial averages well above 100 Bq/m³, while coastal provinces and Quebec tend to run lower.
Importantly, national averages are not a useful benchmark for your home. Your house sits on specific soils and bedrock, has its own foundation characteristics, and is affected by your local climate and lifestyle. The only way to know your level is to test.
How Long Does Exposure Take to Cause Harm?
Radon-induced lung cancer develops over years or decades of cumulative exposure — it is not an acute hazard like carbon monoxide. This is why long-term testing (90 days or more) is recommended: it captures your true average exposure across seasons, which is what determines your actual risk.
The risk also compounds with smoking. A smoker living in a high-radon home faces dramatically elevated lung cancer risk compared to either risk factor alone. Non-smokers are not immune — radon is the leading environmental cause of lung cancer in non-smokers in Canada.
What to Do if Your Radon Level is High
If your test result exceeds 200 Bq/m³:
- Don't panic. Radon mitigation is reliable, affordable, and effective. A properly installed SSD system will reduce your level by 80–99%.
- Contact a C-NRPP certified mitigator or, if you're comfortable with DIY, purchase a fan and installation kit.
- Re-test after mitigation to confirm the system is working. Most systems reduce levels to well below 100 Bq/m³.
- Run the fan continuously. Radon mitigation fans must operate 24/7 to maintain sub-slab depressurization.
Browse our radon mitigation fans and installation parts, or read our full guide on how radon mitigation works.
How to Test Your Home
The most reliable and cost-effective testing method is a long-term alpha track test kit, placed in the lowest occupied area of your home for a minimum of 90 days. The detector is then mailed to a certified lab for analysis.
Our Radtrak³ Long Term Alpha Track Test Kit is analyzed by an accredited radon laboratory, trusted by homeowners and inspectors across Canada. Return the detector using the included pre-addressed mailer and access your full results report online.
