Radon in Quebec: Levels, Risk, Rules & What to Do

Flat-vector map of Canada with Quebec highlighted in coral on a cream background, next to a radon detector canister

A note before you read. This is general consumer information for Quebec homeowners, buyers, sellers, landlords, and tenants, drawn from publicly available sources from Health Canada, the INSPQ, the Government of Quebec (MSSS), the OACIQ, the RBQ, and others. It is not medical, legal, or warranty advice. Results are reported against the Health Canada guideline of 200 Bq/m³; RadonTest.ca coordinates testing logistics and does not interpret individual results or provide health assessments.

Key facts at a glance

  • In Quebec, about 1 in 6 homes (16.7%) have a radon level at or above the 200 Bq/m³ guideline, according to the 2024 national study (Evict Radon / University of Calgary). Health Canada's 2012 Survey put the figure at 8%, but up to 25% of homes in some regions.
  • Radon is the number one cause of lung cancer in non-smokers. In Quebec, the government (MSSS) estimates it is associated with more than 1,000 lung-cancer deaths each year.
  • Levels vary enormously from one region to the next. Estrie (the Eastern Townships, about 1 in 4 homes) and the Outaouais (notably Chelsea, Cantley, and the Pontiac) are higher-risk areas. Any home can have a high level — the only way to know is to test.
  • The Health Canada guideline is 200 Bq/m³ (annual average). Above it, Health Canada recommends taking corrective action within one year — sooner the higher the level.
  • Quebec does not have Ontario's Tarion equivalent. The Garantie de construction résidentielle (GCR) plan does not explicitly cover radon. On the other hand, the Quebec building code has required radon protection in new homes everywhere in the province since June 2, 2022.
  • A valid test runs for at least 91 days (a long-term test). Fixing a home typically costs $2,500 to $4,500, and a system usually installs in about a day.

How much radon is in Quebec homes?

Radon is a naturally occurring radioactive gas with no colour, smell, or taste. It comes from the breakdown of uranium in soil and bedrock, and it seeps up and accumulates indoors. Every home has some; what matters is how much.

Two large datasets describe Quebec, and they don't measure exactly the same thing:

  • Health Canada's Cross-Canada Survey (data collected 2009–2011, published 2012). About 8% of Quebec homes were above 200 Bq/m³ — but up to 25% in some regions.
  • The 2024 national study (Evict Radon / University of Calgary). It puts Quebec at about 1 in 6 homes (16.7%) above 200 Bq/m³, with a weighted geometric-mean concentration of about 77.7 Bq/m³ — very similar to Ontario. For Greater Montreal, the study finds 17.4% of homes above the guideline (average of about 82.4 Bq/m³).

The two figures (8% in 2012, 16.7% in 2024) aren't contradictory: they come from different studies, years, and methods. The trend is the important part — as more homes are tested, the measured share above the guideline rises, and Health Canada now uses "1 in 5 homes" as its national headline. The Government of Quebec, for its part, notes that the average concentration in Quebec basements is about 37 Bq/m³ — which goes to show that the average tells you nothing about your particular home. (See how the provinces compare in our radon levels by province overview.)

What this means for you: don't rely on your neighbour's result. Two homes side by side can read very differently depending on soil, foundation, and ventilation. Only a long-term test reveals your own concentration.

Radon by region in Quebec

Quebec's radon map is very uneven. Here are a few regional pictures, backed by the public-health authorities:

  • Estrie (the Eastern Townships) — a high-risk area. The Estrie public-health authority estimates that about 1 in 4 homes there have a radon level that is too high, above the provincial average.
  • Outaouais — among the highest concentrations in Quebec. The CISSS de l'Outaouais reports an average basement level of about 68.3 Bq/m³, attributed to high uranium concentrations in the bedrock. The areas of Chelsea, Cantley, and the Pontiac are flagged as higher-risk.
  • Greater Montreal. The 2024 study finds about 1 in 6 homes (17.4%) above 200 Bq/m³, and more than 1 in 4 (28%) between 100 and 199 Bq/m³ — a reminder that even major centres are not spared.

Other regions (Mauricie, Abitibi-Témiscamingue, Chaudière-Appalaches, Saguenay–Lac-Saint-Jean, Montérégie) also have affected pockets; in the absence of precise, recent regional data, the only certainty is that you have to test home by home.

Radon by city in Quebec — we publish a detailed local guide for each major city:

Why radon varies in Quebec: the geology

A home's radon level depends on how much uranium and thorium are in the soil and bedrock beneath it. Quebec's geology comes down to essentially three broad domains:

  • The Canadian Shield (the north and part of the southeast) — ancient crystalline bedrock, locally rich in uranium.
  • The St. Lawrence Lowlands — sedimentary rock (shales) covered by thick glacial deposits; this is also where you find the Montérégian igneous intrusions.
  • The Appalachians (Estrie and the southeast) — uranium-bearing meta-sediments that go a long way toward explaining why this region is among the most affected.

According to the INSPQ, the highest emission potential is tied to uranium-rich units — black shales, acidic igneous rocks, carbonatites — especially where they aren't covered by low-permeability surface deposits. In other words, Quebec radon is not a simple matter of "North = high, South = low": some of the most affected areas (Estrie, the Outaouais) sit on particularly uranium-bearing sedimentary or metamorphic formations.

Is radon dangerous? The health risk in Quebec

Radon is classified by the International Agency for Research on Cancer as a Group 1 carcinogen — the highest category, the same as tobacco smoke and asbestos. The official figures:

  • Radon is the number one cause of lung cancer in non-smokers, and the second leading cause overall after smoking (Health Canada).
  • Across Canada, about 16% of lung-cancer deaths are associated with radon — more than 3,000 deaths a year.
  • In Quebec specifically, the government (MSSS) estimates that radon is associated with more than 1,000 lung-cancer deaths each year — of which about 60% are in people who smoke, 30% in former smokers, and 10% in people who have never smoked. (The INSPQ estimated this burden at about 430 deaths a year in a 2004 analysis; the current government estimate is higher.)

Health Canada frames the risk proportionately, and so do we: there is no level of radon that is completely risk-free; the risk below the guideline is small, and it is ultimately each homeowner's choice what level of exposure they are willing to accept. Radon exposure acts over the long term, with no immediate symptoms. The point isn't to alarm: radon is a measurable, fixable risk, and testing is inexpensive. (To sort fact from fiction, see our top 10 radon misconceptions.)

The Health Canada guideline and what your result means

Canada's guideline is 200 becquerels per cubic metre (Bq/m³), measured as an annual average in a normally occupied area. It's a health-based guideline, not a hard legal limit for private homes. Here is what Health Canada recommends:

  • At or above 200 Bq/m³: take corrective action to reduce the level, within one year — and sooner the higher the result.
  • Below 200 Bq/m³: no corrective action is recommended, though no level is risk-free; some households (especially where someone smokes) choose to act toward the more protective 100 Bq/m³ reference level recommended by the WHO.

Your result is a concentration, not a pass/fail — it sits on a spectrum. To understand what each range of results means and what Health Canada recommends, see our guide on how to read your radon test results and our comparison of the Health Canada, WHO, and US thresholds.

How to test in Quebec

Testing is the only way to know your home's level, and it's straightforward:

  • Use a long-term test of at least 91 days (three months). Radon swings from day to day and season to season; an average over 91 days or more reflects your real exposure. Short-term tests are only for checking a mitigation system, never for deciding whether to act.
  • The heating season (roughly October to April) is ideal, because a closed-up home gives a conservative reading — but you can start any time of year. A result above the guideline is worth acting on regardless of season; a low off-season result is worth confirming over a winter. (See when is radon testing season.)
  • Place the detector in the lowest lived-in level (often the basement if it's used), in a room occupied more than four hours a day, about 30 cm off the floor, away from drafts, vents, and direct sun. Not the kitchen, bathroom, or laundry room.
  • Use a C-NRPP-approved test. RadonTest.ca kits use an alpha-track detector analysed by a C-NRPP-certified laboratory. (To compare long-term tests and digital monitors, see our guide.)

Where to get your test: order a RadonTest.ca kit — the detector, analysis by a C-NRPP-certified laboratory (with an all-in-Canada analysis option), tracked shipping both ways, and your result delivered with Health Canada context are all included. One caution about cheaper kits: not every hardware-store kit is analysed by a C-NRPP-certified laboratory — see our comparison of hardware-store radon test kits.

When to retest. Health Canada recommends testing again after any renovation affecting your home's structure or ventilation (finishing a basement, a new furnace, adding a bathroom), after an energy retrofit (windows, insulation, air sealing), or after excavation near the foundation. If you install a mitigation system, retest every 5 years to confirm it's still working. There's no blanket "every 5 years" rule for an unmitigated home — the trigger is change.

If your level is high: mitigation in Quebec

A result above 200 Bq/m³ is a solvable problem (here's what to do if your radon level is above 200 Bq/m³). Health Canada recommends hiring a C-NRPP-certified mitigation professional.

How it works. The standard, most effective method is active soil depressurization (sub-slab depressurization). A pipe is installed through the foundation slab and a continuously running fan draws radon from beneath the home and vents it outside, before it can enter the indoor air. In most homes this reduces radon by more than 80%, and a system usually installs in less than a day. A few points a good contractor will handle: the fan must run continuously (never switched off); the installer should check that the system doesn't cause back-drafting of a furnace, water heater, or fireplace; and the work should be verified with a test after start-up, then confirmed with a long-term test the following heating season — ideally not by the company that installed the system.

What it costs in Quebec. A professional system typically costs between $2,500 and $4,500 (ranges observed in the industry), depending on the home's characteristics. Running the fan costs on the order of a few tens of dollars a year in electricity. (See radon mitigation cost in Canada.)

Finding a certified professional. The Canadian National Radon Proficiency Program (C-NRPP) certifies measurement professionals, mitigation professionals, and laboratories; it is recognized by Health Canada and by Quebec's Ministère de la Santé et des Services sociaux. Search for a professional in the directory at c-nrpp.ca/find-a-professional (language selector at the top of the page). RadonTest.ca does not perform mitigation and does not recommend any specific company. (See also how to choose a mitigator.)

Quebec's radon rules

This is where Quebec differs from Ontario — differently — and it's worth being clear about both sides of the coin.

New-home warranty: no radon coverage (unlike Ontario)

Ontario is the only province whose new-home warranty (Tarion) explicitly covers radon mitigation, up to $50,000. In Quebec, that's not the case. The mandatory Garantie de construction résidentielle (GCR) plan does not name radon among the covered defects and provides no radon-mitigation indemnity. The only theoretical recourse would run through the general framework of latent defects (3 years) or defects in design, construction, or the soil (5 years) — a discretionary and unestablished avenue for radon. In short, don't count on a new-home warranty to pay for mitigation in Quebec. (For the province-by-province picture, see does your new-home warranty cover radon?)

Building code: mandatory radon protection (and ahead of the curve)

Here is where Quebec is ahead of several provinces: since June 2, 2022, the Quebec building code has required protective measures against soil gases (including radon) in new homes, everywhere in the province (the old notion of "recognized risk areas" was dropped; the transition period ended on July 8, 2023). The measure requires a passive radon collection and extraction column — more than a simple capped rough-in pipe — with sealing criteria, designed so that it can be easily upgraded to an active system if needed. The requirements reference the CAN/CGSB-149.11-2019 standard. The code applies to new construction: it imposes nothing on existing homes.

Selling a home: disclosure in Quebec

In Quebec, the Seller's Declarations (DV) form is mandatory for the sale, through a broker, of a primarily residential building with fewer than five dwellings by a natural person. Radon disclosure is not a separate obligation in itself, but radon is an unfavourable factor the seller must declare if they are aware of it, and the broker must ask whether any tests or corrective work have been done. The OACIQ also offers a standard clause (3.21) that lets the promise to purchase be made conditional on a radon test, with funds held until the result is in. Under civil law, a known and concealed latent defect triggers the seller's liability. Bottom line: if you've tested and know the level is high, declare it; if you're buying, make radon part of your due diligence. (See radon when buying or selling a home.)

Radon in the workplace

Quebec's Regulation respecting occupational health and safety (RSST) sets no specific radon exposure limit: radon falls under the employer's general duty to protect workers' health, supported by Health Canada's 200 Bq/m³ guideline. Separately, federally regulated workplaces in Quebec (banks, telecommunications, interprovincial transport, air transport, federal operations) are covered by a new federal regulation, SOR/2026-10, which sets a binding limit of 200 Bq/m³ (replacing the old 800 Bq/m³ limit) and comes into force around February 2027. For rental properties, see our guides for landlords and tenants.

Financial help in Quebec

  • There is no Quebec provincial radon grant or tax credit for mitigation. Unlike Ontario (where the Tarion warranty can cover mitigation in new homes), Quebec offers no dedicated provincial radon program, and Rénoclimat does not fund radon mitigation.
  • Lungs Matter program (Canadian Lung Association) — national, available to Quebecers: up to $1,500 toward mitigation, prioritizing people diagnosed with lung cancer and lower- to modest-income households.
  • There is currently no federal radon-mitigation grant open to the general public.

Frequently asked questions

What is a risk-free radon level in Quebec? No level is completely risk-free. The Health Canada guideline is 200 Bq/m³, the level above which it recommends acting within one year. The risk below the guideline is small but not zero, and the WHO recommends a more protective 100 Bq/m³ threshold.

How common is radon in Quebec? Health Canada's Survey (2012) found 8% of homes above the guideline (up to 25% in some regions); the 2024 national study puts Quebec at about 1 in 6 homes. Nationally, Health Canada says 1 in 5 homes.

Where is radon worst in Quebec? Estrie (about 1 in 4 homes) and the Outaouais (Chelsea, Cantley, the Pontiac) are among the most affected areas; Greater Montreal is at about 1 in 6. But any home can be high — only a test will tell you.

Does the new-home warranty cover radon in Quebec? No. Unlike Ontario's Tarion warranty, the GCR plan does not explicitly cover radon. Confirm any specific situation with the GCR.

Do I have to disclose radon when selling my home in Quebec? There is no separate obligation to disclose radon, but if you know of a high level, you must declare it as an unfavourable factor; the Seller's Declarations form is mandatory for a sale through a broker.

How much does radon mitigation cost in Quebec? Typically $2,500 to $4,500 depending on the home.

Are new homes in Quebec protected against radon? Yes — since June 2, 2022, the Quebec building code has required a passive radon extraction column in new homes, everywhere in Quebec. It's passive protection: a fan is added if a test later reveals a high level.

How long does a radon test take? At least 91 days (three months) for a valid long-term result. Short-term tests aren't suitable for deciding whether to act.

Test your Quebec home

Radon is invisible, common across many regions of Quebec, and fixable. The only way to know your home's level is a long-term test.

Order your RadonTest.ca kit → — analysis by a C-NRPP-certified laboratory (with an all-in-Canada analysis option), tracked shipping both ways, and your result delivered with Health Canada context.

Sources

  1. Health Canada — Radon guideline / About radon (200 Bq/m³; corrective action within one year), modified 2025-09-24. https://radontest.ca/links/hc-guideline
  2. Health Canada — Reducing radon levels in your home (>80%; C-NRPP). https://radontest.ca/links/hc-mitigation-guide
  3. Government of Quebec (MSSS) — Residential radon (more than 1,000 deaths/year in Quebec; basement average ~37 Bq/m³), updated 2025-11-20. https://www.quebec.ca/habitation-territoire/milieu-de-vie-sain/radon-domiciliaire
  4. 2024 national study (Evict Radon / University of Calgary) — Quebec ~16.7% / 1 in 6; Greater Montreal 17.4%. https://crosscanadaradon.ca/survey/
  5. Take Action on Radon — Quebec (summary of the 2012 Health Canada Survey: 8%, up to 25% in some regions). https://takeactiononradon.ca/provinces/quebec/
  6. INSPQ — Radon in Quebec: health risk assessment (publication 352, 2004–2005; historical estimate of about 430 deaths/year) and radiogeochemical mapping. https://www.inspq.qc.ca/publications/352
  7. Estrie public-health authority — Radon (~1 in 4 homes). https://www.santeestrie.qc.ca/soins-services/conseils-sante/environnement-sains-securitaires/radon
  8. CISSS de l'Outaouais — Radon (basement average 68.3 Bq/m³; Chelsea, Cantley, Pontiac). https://cisss-outaouais.gouv.qc.ca/
  9. Garantie de construction résidentielle (GCR) — Is my problem covered? (no radon coverage named). https://www.garantiegcr.com/fr/acheteur/conseils-gcr/ma-problematique-est-elle-couverte-1-an-3-ans-ou-5-ans-par-gcr/
  10. Régie du bâtiment du Québec (RBQ) — Protective measures against soil gases for all of Quebec (in force 2022-06-02). https://www.rbq.gouv.qc.ca/salle-de-presse/les-nouvelles/
  11. OACIQ — Radon (Seller's Declarations mandatory; standard clause 3.21 "Radon measurement test"). https://www.oaciq.com/fr/titulaires-de-permis/guides-pratiques-professionnelles/environnement/radon/
  12. LégisQuébec — Regulation respecting occupational health and safety (RSST) (no specific radon limit). https://www.legisquebec.gouv.qc.ca/fr/document/rc/s-2.1,%20r.%2013
  13. Canada Gazette, Part II — SOR/2026-10 (federal workplaces: 200 Bq/m³, in force ~Feb. 2027), 2026-02-11. https://gazette.gc.ca/rp-pr/p2/2026/2026-02-11/html/sor-dors10-eng.html
  14. Canadian Lung Association — "Lungs Matter" grant program (up to $1,500). https://www.lung.ca/air-quality/radon/lungs-matter-radon-mitigation-support

Related Quebec radon guides

Lab analysis is performed independently by a C-NRPP-certified laboratory. Results are reported against the Health Canada guideline of 200 Bq/m³. RadonTest.ca coordinates kit logistics and sample submission only — it does not interpret or modify lab results and does not provide medical, legal, or warranty advice. Information attributed to Health Canada, the GCR, the OACIQ, and others is summarized from the public sources listed above; confirm details that may change (warranty coverage, code requirements, programs) with the responsible body.