What does Bq/m³ mean?
Becquerels per cubic metre is the unit used to describe radon concentration in air.
The result to use is the average over the valid test period. Electronic monitors may also show hourly or daily values, but those short readings naturally rise and fall and should not be compared on their own with the annual guideline.
What is Canada’s guideline?
The Canadian guideline is 200 Bq/m³ for the long-term average radon concentration in a home.
Health Canada recommends corrective action above this level. The guideline is an action point, not a line between zero risk and danger, and exposure is generally a long-term issue rather than an immediate emergency.
Why does test duration matter?
Health Canada does not recommend making corrective-action decisions from tests shorter than 91 days. If your test was shorter, continue or repeat a long-term measurement during the heating season before treating the number as the home’s annual average.
Can readings fluctuate?
Yes. Weather, seasonal conditions, ventilation, open windows and building operation can all affect radon. Use the longest, most representative average available rather than reacting to one spike.