You finally received your radon test results, and they are expressed as a number followed by an unfamiliar unit: Bq/m³. Is your number good or bad? Should you act, or relax? This guide demystifies how radon is measured, what Health Canada's guideline means, and how to make sense of your specific result.
Radon is measured in becquerels per cubic metre, written as Bq/m³. A becquerel is a unit of radioactivity equal to one radioactive decay event per second. So a reading of 200 Bq/m³ means that, in each cubic metre of air in your home, 200 radon atoms are decaying every second. The higher the number, the more radioactive decay is happening in the air you breathe, and the greater your potential exposure.
You may occasionally see radon expressed in picocuries per litre (pCi/L), a unit used in the United States. For reference, 200 Bq/m³ is roughly 5.4 pCi/L. In Canada and Alberta, becquerels are the standard, so that is the number to focus on.
Health Canada has set a guideline of 200 Bq/m³ for indoor radon in homes. The recommendation is clear:
It is important to understand what a "guideline" is. It is not a hard line between "safe" and "dangerous." Rather, it is the level at which the benefit of taking action clearly outweighs the cost. Health risk from radon exists on a continuous scale.
This is one of the most important concepts to grasp. Radon risk does not switch on at 200 and switch off below it. Even levels under the guideline carry some small risk, and very high levels carry substantially more. Health Canada's broader advice is to reduce radon as low as reasonably achievable (ALARA). A home at 180 Bq/m³ technically meets the guideline, but a homeowner who reduces it further is still lowering their long-term risk.
Your home is in good shape. No mitigation is needed. It is still worth re-testing every few years or after major renovations, since levels can change.
You are within the guideline but not by a wide margin. Because a single short test can under- or over-read, consider confirming with a long-term test. Some homeowners choose to mitigate proactively at this level for additional peace of mind.
Plan for mitigation. A reading of 300 warrants timely action; a reading of 1,000 or more warrants prompt attention. The good news is that mitigation reliably brings even very high homes down to a small fraction of the guideline.
Alberta's geology produces ample radon, and our cold-climate homes are built tight and run furnaces that draw soil gas indoors during winter. It is not unusual to see Calgary homes test in the several-hundred range, and some considerably higher. A high number is not a reflection of a poorly built home — it reflects the soil beneath it.
The most accurate result comes from a long-term test (90+ days) during the heating season, ideally placed by a C-NRPP certified professional. Once you understand your number in Bq/m³ relative to the 200 guideline, your path forward is clear. If your Calgary home is above the guideline, Onyx Radon can lower it dramatically and verify the result — turning an abstract number into rock-solid protection.
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