Sump pit and radon an open hole at the low point of the slab
A sump drops below the slab, where gas moves in the gravel. Without a sealed lid, the house pulls that air whenever the basement is under negative pressure. A gasketed lid with a pass-through for the pump closes that path. It does not treat the rest of the slab.
Do not measure inside the sump. Health Canada says concentrations there are not representative of the occupied room. The detector stays in the lived-in room. If a mitigation system starts at the sump, that is a suction point with a sealed cover and a pipe to the roof, not the sump pump’s own fan.
References: Health Canada, radon: what you need to know and the 200 Bq/m³ guideline. The two-year window between 200 and 600, and the one-year window above 600, come from Health Canada’s guide for radon measurements in homes.
The 4-day test is a first reading. The 91-day test covers the minimum of three months Health Canada asks for. Both are $59 before tax. Shipping, the prepaid return and the lab are included. Tax is extra. The PDF report goes out within 2 business days after the lab receives the detector.
Above 200 Bq/m³, mitigation starts with a quote. Gaz Radon is C-NRPP certified for testing and for installation, and ships kits across Canada.
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