Radon upstairs the gas enters at the bottom and dilutes
Radon enters from below. As it rises, it dilutes with the air in the house. Health Canada therefore places the detector at the lowest lived-in level, not on the landing “because it is easier.” A second-floor bedroom can be under 200 while the basement is at 800.
The reverse also exists: if nobody uses the basement and all of life is on the main floor, the main floor is what counts. A second-floor number does not declare the house. If the basement is extreme, some of it rises. Do not guess the share. Measure the room where you sleep.
Apartment: which floor. Why it rises at night.
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.
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