HomeZoneReportHomeZoneReportRadon is the second-leading cause of lung cancer in Canada, and it's a problem that's easy to ignore because you can't see, smell, or taste it. The good news: it's also one of the most fixable home risks. Here's what every Canadian buyer and owner should understand about radon, how to test for it, and what to do if levels are high.
Radon is a radioactive gas that forms naturally when uranium in soil and rock breaks down. It seeps up through the ground and into homes through cracks in foundations, gaps around pipes, and sump pits. Because Canadian winters keep windows closed and homes tightly sealed, radon can build up indoors to levels well above what you'd find outside. Health Canada estimates that about 7% of Canadian homes have radon levels above the national guideline of 200 becquerels per cubic metre (Bq/m³) — and some regions, including parts of Ontario, Manitoba, Saskatchewan, and the Maritimes, see much higher rates.
Health Canada's guideline is 200 Bq/m³. If a long-term test shows levels above that, the recommendation is to take action to reduce them. It's worth noting the guideline is a target, not a hard line: even levels between 100 and 200 Bq/m³ carry some risk, and many experts suggest fixing anything above 100 if it's practical. The lower you can get the level, the lower the risk — there's no "safe" threshold, just lower and higher.
Testing is cheap and easy. You can buy a do-it-yourself radon test kit (usually a charcoal canister or alpha-track detector) for $30 to $60 at most hardware stores or online, mail it to a lab, and get results in a few weeks. For the most reliable picture, use a long-term test that runs for at least 90 days — radon levels swing with the seasons, and a short test in summer can badly understate winter levels. If you're buying a home, ask the seller whether a test has been done and request the results. If none exists, budget for a test as part of your due diligence.
Below 200 Bq/m³: the home meets the Health Canada guideline. Between 200 and 600 Bq/m³: Health Canada recommends fixing the home within a reasonable time frame. Above 600 Bq/m³: fix it as soon as possible. Remember that a single reading is a snapshot — if you're near the guideline, a longer test gives you a more confident answer before you spend money on mitigation.
High radon is very fixable. The standard solution is a radon mitigation system: a vent pipe and fan that draws radon from beneath the foundation and exhausts it safely above the roofline. A certified professional typically installs one for $1,500 to $3,000, and it can cut indoor levels by 90% or more. Sealing cracks and improving ventilation help, but a proper sub-slab depressurization system is the reliable fix. After installation, retest to confirm the system is working.
Test with a long-term (90-day) kit · Compare to the 200 Bq/m³ guideline · Ask the seller for existing test results · Budget for mitigation if levels are high · Retest after any mitigation work
An elevated radon reading shouldn't kill a deal — it's a fixable, well-understood problem with a known cost. What matters is knowing before you close. If a test comes back high, you can negotiate on price, ask the seller to install a mitigation system, or factor the $2,000-ish fix into your own budget. The worst outcome is discovering it after you've moved in and spent your renovation money elsewhere. A few dollars and a few weeks of testing turn an invisible risk into a line item you can plan around.
A HomeZoneReport property intelligence report compiles environmental and property risk factors for any Canadian address — alongside market, school, and neighbourhood data — in one report, usually within 24 hours.