WHO at 100, Canada at 200 three policies, one laboratory number
The Canadian guideline, adopted in 2007, is 200 Bq/m³ as an annual average in the occupied zone. Health Canada asks you to act if you exceed that figure, faster if the level is higher, and to go as low as is practicable. There is no risk-free level.
The World Health Organization proposes a reference level of 100 Bq/m³. The US Environmental Protection Agency uses 4 pCi/L, about 148 Bq/m³. A report at 160 Bq/m³ is under the Canadian guideline and above the American reference. That is not a laboratory error. Those are three policies.
Which one to use here
In Canada, the usual comparison is 200. An owner can decide to mitigate at 100 because they want the WHO margin. The mitigation system is judged by the number after the work, not by a slogan. Between 200 and 600. Above 600. Reading Bq/m³.
Reference points: Health Canada, what you need to know about radon and the 200 Bq/m³ guideline. The two-year timeline between 200 and 600, and one year above 600, comes from Health Canada’s guide for radon measurements in homes.
The 4-day test gives a first reading. The 91-day test covers the three-month minimum Health Canada asks for. Both are $59 before tax: shipping, return and the laboratory are included, taxes extra. The PDF report is sent within 2 business days after the laboratory receives the detector.
Above 200 Bq/m³, mitigation is confirmed with a quote. Gaz Radon is C-NRPP certified for measurement and mitigation.
Sources
