Radon Is Invisible. Here's Why Winter Testing Matters
Air, heat and moisture · PROBLEM-FIRST
Radon is a naturally occurring radioactive gas that seeps up from the ground into homes, and it cannot be seen or smelled. Health Canada's national guideline sets 200 Bq/m3 as the level above which remediation is recommended, and its testing guidance favours a long-term test spanning at least three months, ideally including the winter months, because radon levels are typically highest when windows and doors stay closed. Late August into early September is a practical time to begin a long-term test: starting now means the test runs through the coldest part of the year and produces a result by winter's end. Niagara sits along the Niagara Escarpment, a geological feature that radon-mapping resources and at least one Niagara-area contractor associate with elevated radon potential in some homes, though every home differs and radon levels can vary significantly from house to house even on the same street, which is exactly why a real test on a specific property is the only way to know its own reading. This section explains that timing mechanism before naming any product.
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AIRTHINGS Corentium Home Radon Gas Detector, Canadian Version in Bq/m
price: not in record Price and availability change, so check the current listing on Amazon.ca.
- Power Source: 3 AAA alkaline batteries, included, rated up to 2 years, manufacturer-published checked 2026-08-26
- Measurement Method: Passive diffusion chamber with alpha spectrometry, hourly sampling interval, Bq/m3 native display since this is the Canadian-market version of the device checked 2026-08-26
- Accuracy And Test Duration: Within 10 percent of a true reading after 7 days at the 200 Bq/m3 guideline level, or after 4 days at a higher concentration; Health Canada's own long-term-test guidance calls for at least 91 days for the most reliable overall reading checked 2026-08-26
Specs sourced from the manufacturer's Amazon.ca listing.
ASIN B00H30TLPAAirthings 325 Corentium Home 2 Smart Digital Radon Detector
price: not in record Price and availability change, so check the current listing on Amazon.ca.
- Connectivity: Bluetooth to the Airthings smartphone app, plus onboard temperature and humidity sensors, listing-published checked 2026-08-26
- Units And Accuracy: Toggles between Bq/m3 and pCi/L in the app; same stated accuracy class as the original Corentium Home, within 10 percent after 7 days at 200 Bq/m3 checked 2026-08-26
Specs sourced from listing 1, listing 2.
ASIN B0F84C4ZZMSafety Siren Pro Series3 Radon Gas Detector, HS79712 Canada
price: not in record Price and availability change, so check the current listing on Amazon.ca.
- Power Source: Plugs into a standard 120V wall outlet, per the independently published user manual checked 2026-08-26
- Display: Digital LED readout in Bq/m3 (Canadian model), showing both short-term and long-term average checked 2026-08-26
- First Reading And Regulatory Note: Gives an initial reading after 48 hours, then continues updating hourly, and keeps monitoring after the initial long-term test period ends; Ontario's 2024 construction rules added a radon soil-gas rough-in requirement for new residential construction only, effective January 1, 2025 per one source and April 1, 2025 per the province's own home-builder licensing body, both dates named since they differ; this does not apply to existing homes checked 2026-08-26
Specs sourced from listing 1, listing 2.
ASIN B00643TO68Every spec above is copied from the manufacturer's own published listing or spec sheet, with the date it was checked.
Who this isn't for
This is not for anyone wanting a same-week answer; a short-term test can give a rough read, but Health Canada's own guidance favours a long-term test spanning winter for a reliable result, so a household needing an immediate decision should treat a short reading as preliminary, not final. It is also not medical, legal, or installation advice; an elevated reading should be followed up with a second test and, if confirmed, a certified radon mitigation professional, not acted on from a single number alone.