In Quebec the question comes up constantly: what is the radon "standard"? The honest answer is that there is no Quebec standard setting a number. What exists is three separate things that are routinely confused with one another: a Canadian guideline of 200 Bq/m³, a general duty placed on employers by the CNESST regime, and a binding federal limit that takes effect on 30 January 2027 for federally regulated workplaces.
The essentials: 200 Bq/m³ as an annual average is Health Canada's guideline. It applies to all dwellings and all indoor spaces in Canada, including Quebec. It is not a provincial law. Neither the LSST nor the RSST sets a maximum radon concentration. From 30 January 2027, a legal limit of 200 Bq/m³ applies to federally regulated workplaces located in Quebec.
1. The Canadian guideline: 200 Bq/m³
Health Canada, working with the Federal-Provincial-Territorial Radiation Protection Committee, set the Canadian radon guideline at 200 becquerels per cubic metre (Bq/m³), as an annual average, in the normally occupied areas of a building. It was adopted by the Government of Canada in 2007, replacing an earlier threshold of 800 Bq/m³.
Three points that matter:
- It is a guideline, not a law. It is not enforceable in itself, but it is the reference used by every regulator, inspector and practitioner in the country.
- It refers to an annual average, not a single reading. Concentrations vary hour to hour and season to season.
- There is no risk-free threshold. According to Health Canada, 200 Bq/m³ is the level at which action is recommended — it is not a line below which radon stops mattering.
The timeframe for acting depends on the building. For homes, Health Canada's current guidance is to take corrective action within one year of a result above 200 Bq/m³, and the higher the level, the sooner. For public buildings and workplaces, the Guide for Radon Measurements in Public Buildings sets a two-tier timeframe in its Table 3: less than one year above 600 Bq/m³, and less than two years between 200 and 600 Bq/m³. These are two different regimes, and the one that applies to you depends on the building you are measuring.
2. At work: the CNESST regime
This is the point most people get wrong. Neither the Act respecting occupational health and safety (LSST) nor the Regulation respecting occupational health and safety (RSST) sets a maximum radon concentration for provincially regulated workplaces. You can search the RSST for a radon number: there isn't one.
That does not let the employer off. In Quebec, an employer must take the measures necessary to protect the health of its workers, and must identify and control the hazards present in its establishment as part of its prevention programme. Radon — a Group 1 carcinogen according to the IARC, and the leading cause of lung cancer in people who have never smoked — is a recognised hazard. The reference used in practice remains Health Canada's 200 Bq/m³.
Full detail: the Quebec employer's obligations (CNESST).
3. The new federal limit: 200 Bq/m³ on 30 January 2027
Regulation SOR/2026-10, published in the Canada Gazette on 11 February 2026, lowers the radon exposure limit from 800 to 200 Bq/m³ as an annual average for federally regulated workplaces. It comes into force on 30 January 2027.
Unlike Health Canada's guideline, this is a binding legal limit. It covers federally regulated employers — chartered banks, telecommunications and broadcasting, interprovincial transport, postal and courier services, pipelines, Crown corporations, First Nations band councils, the federal public service — including their establishments located in Quebec.
A provincially regulated Quebec employer is not covered by this limit. A federally regulated Quebec employer is covered in full. Detail: the new federal limit explained.
3.1 Guidance or obligation: the distinction that matters
Health Canada recommends testing and action. The federal regulation requires it: the employer "must ensure" that no employee is exposed above 200 Bq/m³. That is the difference between guidance and a legal obligation.
For a provincially regulated Quebec employer, the obligation therefore comes not from the guideline itself but from the general duty to protect workers' health. The guideline supplies the number against which the reasonableness of the measures taken will be judged — and the fact that the federal government has now written 200 Bq/m³ into its own regulations makes it harder to argue that some other number would be reasonable.
4. What does not exist in Quebec
To be clear, because these claims circulate:
- No Quebec standard setting a radon number for dwellings or for provincially regulated workplaces.
- No testing obligation imposed on owners, landlords, schools or childcare centres in Quebec.
- No radon-specific disclosure obligation in a residential real-estate transaction in Quebec, although the general rules on latent defects and material facts may apply depending on the circumstances.
Two Canadian jurisdictions are exceptions where childcare is concerned: the Interior Health region of British Columbia ordered testing in 2017, and Yukon announced a phased licensing requirement in 2017. Quebec has no equivalent.
5. How to measure using the recognised method
The guideline refers to an annual average. The method Health Canada recognises for establishing one is a long-term measurement of at least three months, during the heating season, using a C-NRPP-listed device analysed by an accredited laboratory. Short-term measurements are not acceptable for deciding whether corrective action is needed.
In a dwelling: one detector at the lowest level where you spend four hours or more a day. In a public building or a workplace the protocol is different: one detector in every occupied room in contact with the ground, one per 200 m² in large rooms, plus quality-control measurements.
6. Where Quebec stands
Radon concentrations vary widely from one region to another according to geology. Several regions of Quebec show high radon potential, and regional surveys exist — but regional data indicates a probability, not a result. Two neighbouring houses can show very different concentrations.
You can look up measured results for your area on our Canada radon map. The only way to know the concentration in a specific building remains measuring it.
Frequently asked questions
What is the radon standard in Quebec?
There is no Quebec standard setting a number. The reference is Health Canada's Canadian guideline: 200 Bq/m³ as an annual average. From 30 January 2027, a legal limit of 200 Bq/m³ applies to federally regulated workplaces.
Is 200 Bq/m³ a legal limit in Quebec?
For provincially regulated workplaces and for dwellings: no, it is a guideline. For federally regulated workplaces: yes, from 30 January 2027.
Does the CNESST set a radon limit?
No. Neither the LSST nor the RSST sets a maximum concentration. The employer remains required to identify and control the hazards present in its establishment.
Do Quebec schools and childcare centres have to measure radon?
No regulatory obligation applies in Quebec. Schools and childcare services operated by a band council are, however, federally regulated. See our radon at work and in childcare FAQ.
Which device should I use?
A long-term C-NRPP-listed device, analysed by an accredited laboratory, deployed for at least three months during the heating season.
New construction in Quebec: the Construction Code and radon · the GCR warranty.
Further reading
The 2027 federal limit (SOR/2026-10) · Radon at work and in childcare FAQ · The Quebec employer's obligations · Canada radon map
RadonTest.ca handles the logistics of testing and the submission of samples to the laboratory. We do not carry out mitigation work and we do not interpret health risk — Health Canada remains the authority on radon in Canada. This page presents public regulatory information and does not constitute legal advice.
Sources
Health Canada, Government of Canada radon guideline; Health Canada, Guide for Radon Measurements in Public Buildings; Health Canada, Guide for Radon Measurements in Residential Dwellings; Canada Gazette, Part II, vol. 160, no. 3 (SOR/2026-10); Act respecting occupational health and safety (CQLR c. S-2.1) and Regulation respecting occupational health and safety (CQLR c. S-2.1, r. 13); CNESST.