High Radon Levels: What Should I Do?
If your radon monitor or test kit shows an elevated number, the next step depends on the type and duration of the measurement—not just the highest number you saw on the screen.
1. Identify what kind of result you have
Was the result from a three-week screening monitor, a few days of electronic readings, or a long-term measurement lasting at least 91 days? Health Canada’s 200 Bq/m³ guideline is applied to the long-term average—not to an isolated hourly spike.
2. Compare the long-term average with 200 Bq/m³
If a valid long-term test is above 200 Bq/m³, Health Canada recommends action to reduce radon. Its current residential guidance recommends mitigation within one year for levels above 200 Bq/m³ and taking action sooner as the level increases.
| Result | How to think about it |
|---|---|
| Below 200 Bq/m³ | Below the Canadian action guideline, though Health Canada notes there is no completely risk-free radon level. |
| Above 200 Bq/m³ | If this is a valid long-term result, Health Canada recommends corrective action. |
| Short-term reading above 200 | A useful warning signal, but first determine whether you have the long-term average required for the guideline decision. |
| Very high reading | Confirm the measurement context and seek qualified guidance promptly; Health Canada advises acting sooner as concentrations rise. |
3. Don’t rely on opening windows as the solution
Ventilation can temporarily influence a reading, but it is not a dependable substitute for a properly designed mitigation strategy when long-term radon is elevated. The goal is a durable reduction under normal living conditions.
4. Speak with a certified radon professional when mitigation is indicated
Health Canada recommends using a C-NRPP-certified radon mitigation professional. The most common approach is active soil depressurization, but the appropriate design depends on the home.
Want help deciding what comes next?
Send us the approximate radon reading, how long you tested, and a little information about your home.
Official sources
Independent resource: Winnipeg Radon Help provides general educational information and a way to request local assistance. It is not itself a radon testing or mitigation contractor, medical provider, government agency, or emergency service. For testing and mitigation, Health Canada recommends using appropriately qualified professionals, including C-NRPP-certified radon professionals.