Where should a radon detector go in a Nepean house?

Health Canada says all measurements should be made in a normal occupancy area of the lowest lived-in level of the home. A normal occupancy area is any space in which a person spends more than 4 hours per day. In a Nepean house, that means the lowest level where someone actually spends that time.

Health Canada's testing guide sets out the rest:

• The minimum test length is 91 days for a valid estimate, with at least 91 days of the test during the heating season.
• Health Canada strongly recommends testing only with devices that appear on the C-NRPP list.
• Residents should not alter their lifestyle during a long-term radon test.
• Short-term measurements are not appropriate for informing mitigation decisions.
• Results can vary by up to plus or minus 25%.

Ottawa Public Health says radon concentrations vary a great deal within the City of Ottawa, making it difficult to predict radon levels in any one home, and Health Canada recommends every home be tested. Ottawa Public Health puts do-it-yourself long-term kits at $29 to $170.

Health Canada's guideline is to take corrective action if the average annual radon level exceeds 200 Bq/m³ in the normal occupancy area, and it says individuals mitigate within 1 year for levels higher than 200 Bq/m³. For corrective work it points to a C-NRPP certified radon mitigation professional. Radon testing and mitigation as services are covered on ottawaabatement.com.

If you are asking because you are buying, keep the timing in mind: a valid result takes at least 91 days, so a test started during a condition period will not finish inside it unless the condition runs longer than three months.

If you want an inspector to set up the test, ask whether they offer long-term radon testing and which device from the C-NRPP list they use.