FAQ
Radon questions, answered
Short, sourced answers about radon, testing, mitigation, new homes and real estate in Ontario.
Radon and health
What is radon?
A colourless, odourless radioactive gas that forms naturally when uranium in soil and rock breaks down. It can seep into homes and build up indoors, especially in basements.
How dangerous is radon?
Radon is the second leading cause of lung cancer in Canada after smoking, and the leading cause in people who have never smoked. It is linked to about 16% of lung cancer deaths in Canada, more than 3,000 a year.
How long does it take for radon to cause lung cancer?
Radon risk builds over years to decades of exposure. There are no short-term symptoms, and lowering your exposure at any age reduces future risk.
Does radon have a smell?
No. Radon is colourless, odourless and tasteless. The only way to detect it is with a radon test.
Is radon worse for smokers?
Yes. Radon and smoking multiply each other’s effects. At 200 Bq/m³ over a lifetime, the CMAJ estimates lung cancer risk of roughly 17% for smokers compared with about 2% for people who have never smoked.
Testing
Are 48-hour radon tests reliable?
They’re a screen, not a verdict. Radon levels swing with weather and how the house is used, so a few days can sit well above or below the yearly average. C-NRPP says every short-term result should be followed by a long-term test, and that the decision to mitigate should rest on the long-term result. A short test is most useful when it’s far from 200 Bq/m³ and taken in winter.
Where can I buy a radon test kit in Ontario?
Long-term kits are sold online and through some hardware stores, health units and lung health organizations. Look for a kit from a supplier listed with C-NRPP so the lab analysis meets Canadian standards.
Can I get radon results faster than 91 days?
A professional test can give you an early reading in as little as 2 weeks from a calibrated continuous monitor. It’s reliable when the reading is far above or below 200 Bq/m³, less so near it. The 91-day result is still the one to decide on.
Is 4 pCi/L high in Canada?
4 pCi/L is about 148 Bq/m³: the U.S. EPA action level, but below Health Canada’s 200 Bq/m³ guideline. Under Canadian guidance no action is required, though some families choose to reduce it.
My digital monitor shows a big spike. Should I worry?
Short spikes are normal; radon changes hour to hour with weather and how the house is used. Look at the long-term average, ideally over 91 days or more, before deciding.
What is Health Canada’s radon guideline?
200 Bq/m³ as a long-term average in any part of a home where someone spends more than four hours a day. Reduce within 2 years for 200–600 Bq/m³ and within 1 year above 600.
Mitigation
How much does radon go down after mitigation?
A properly designed and installed active soil depressurization system typically reduces indoor radon by 90% or more.
Can a radon system be installed in a finished basement?
Yes. We usually place the suction point in a mechanical or storage room and route the pipe through a closet, chase, the garage or an exterior wall, so finished spaces stay intact.
How much does radon mitigation cost in Ontario?
Most single-family homes fall roughly between $2,000 and $3,500 for a sub-slab depressurization system. Complex homes with several foundations, crawlspaces or difficult pipe routes can cost more. A site assessment gives a fixed price.
How much electricity does a radon fan use?
Typical radon fans draw roughly 20 to 90 watts while running continuously, a modest yearly cost similar to leaving one or two light bulbs on.
Will sealing cracks stop radon?
Sealing helps and is part of every good mitigation, but on its own it rarely brings levels down reliably. There are too many small openings, and new cracks form over time.
Do you guarantee results?
If your follow-up long-term test comes back at or above 200 Bq/m³, we return and adjust or upgrade the system at no cost until it doesn’t. Conditions apply.
New homes and real estate
Do new homes in Ontario need a radon system?
New Part 9 homes under the 2024 Ontario Building Code need a soil gas barrier and a rough-in for a future sub-slab depressurization system. The active fan is only added if a test shows it’s needed.
Does Tarion cover radon?
Yes. Tarion’s new home warranty includes radon remediation, up to $50,000, for seven years from possession when long-term tests (at least three months) show levels above 200 Bq/m³.
Should I walk away from a house with high radon?
Rarely. Radon is one of the most fixable issues in a home; most systems install in a day and reduce levels by 90% or more. It’s usually handled through price or a holdback rather than a cancelled deal.
Can I get a radon test done before my condition deadline?
A professional short-term screening test can usually be scheduled within a typical conditional period. It’s a screen, not a final answer, so plan a long-term test after closing.
Working with us
What areas do you serve?
Windsor-Essex, Chatham-Kent, Lambton, Huron-Perth, Waterloo Region, London, Middlesex, Elgin, Oxford, Norfolk and Brant. See all areas.
How quickly can you come out?
We reply within one business day and usually place detectors within one to two weeks of booking. Your early reading follows 2 weeks after placement. Real estate screening tests can often be scheduled faster.
Are you certified?
Yes. Our team is certified through the Canadian National Radon Proficiency Program (C-NRPP) for radon measurement and mitigation.
Do you work with builders and contractors?
Yes. We run radon programs for builders (rough-ins, activation, post-occupancy testing) and a network for C-NRPP certified contractors. See builders and contractors.
Know your number in one heating season.
Book a radon test with a C-NRPP certified technician: an early reading at 2 weeks, the full result at 91 days. If it’s high, we’ll design a fix and prove it worked.