Someone has asked whether this building has been tested for radon. Possibly a worker, possibly the health and safety committee, possibly a tenant or a parent. And you now need to answer a question you have not previously had to think about.
The good news is that this is a manageable situation and you have almost certainly not done anything wrong. Radon has not historically been part of routine building management in Canada, and the vast majority of Canadian workplaces have never been tested. The question arriving is new. It is not evidence of neglect.
The short version. Find out which rules apply to you first — federal and provincial employers are in genuinely different positions. If you are provincially regulated there is no numeric radon limit anywhere in Canada, but there is a general duty to take reasonable precautions against recognised hazards, and the question having been asked is the thing that changed. A hazard that has been raised is a hazard you know about. What you do next is the whole of it — and testing is usually cheaper and faster than the conversation about whether to test.
Step 1: work out which rules actually apply to you
This determines everything else, and a lot of people get it wrong.
If your organisation is federally regulated — a bank, an airline or airport operation, a railway, an interprovincial trucking or bus company, marine shipping, a pipeline, telecommunications or broadcasting, Canada Post or a courier, a grain elevator, a Crown corporation, a First Nations band council, or the federal public service — then a specific numeric limit applies to you from 30 January 2027, and this is a compliance question with a date attached rather than a discretionary one.
If you are provincially regulated — which covers most Canadian employers, including school boards, hospitals, municipalities, retail, manufacturing, construction and professional services — then no numeric radon limit applies to you, in any province or territory.
There is no third category. Every Canadian employer is one or the other — “private company” is not a separate jurisdiction. A privately owned business, a family firm, a partnership, a non-profit, a charity, a co-operative and a union are all provincially regulated employers unless they operate in one of the federal sectors listed above. If you have been reading “provincially regulated” and wondering whether it means you, it almost certainly does.
Two things worth knowing at the edges. In Yukon, the Northwest Territories and Nunavut, private-sector firms are federally regulated for labour relations but their occupational health and safety is governed by territorial legislation. And most provincial OHS Acts do not reach private homes where the work is done by the owner or occupant, or farming operations unless a specific regulation says otherwise.
Determining this properly is worth ten minutes: which rules apply to your workplace. The jurisdiction question has some genuinely counterintuitive answers — insurance companies and trust companies are provincial for labour purposes despite federal incorporation, and most credit unions are provincial while a handful are federal.
Step 2: understand what actually changed when they asked
If you are provincially regulated, the honest answer to “do we have to test?” is that no regulation requires it.
That is not the end of the analysis, and it would be a mistake to treat it as one.
Every Canadian jurisdiction imposes a general duty on employers to take reasonable precautions to protect the health and safety of workers. General duty clauses do not list hazards — they reach recognised ones. And radon is about as recognised as a hazard gets: a Group 1 carcinogen, identified by Health Canada as the second leading cause of lung cancer in Canada, with a published national guideline of 200 Bq/m³ that applies to all indoor spaces including workplaces.
What changed is that it has now been raised with you. Before the question, radon was a hazard you had not turned your mind to. After it, it is one you know about. General duty provisions are principally concerned with what an employer does once a hazard has been identified — and the answer “we were asked and we did nothing” is the one that is difficult to defend, whatever the source of the question.
Nobody is suggesting an inspector is on their way. They almost certainly are not. But the internal record now shows a question, and it will eventually show an answer.
If the question came through a health and safety committee
Take it more seriously, not because the concern is different but because the process is. Committees have statutory footing, and in federally regulated workplaces an employer must respond in writing to a committee recommendation within a defined period. Many provincial regimes have comparable requirements.
A written question of this kind is on the record whether or not you answer it, so the practical question is only what the answer says.
Step 3: what a good response looks like
You do not need a decision today. You need a response that is honest and specific about what happens next.
A good answer has three parts. Acknowledge the question as legitimate. Say what you are going to find out. Give a date.
“Thanks for raising this. We have not previously tested for radon, and I want to look at it properly rather than give you an off-the-cuff answer. I am going to find out what testing would involve for this building and bring it back to the [committee / team] by [date].”
That is a complete and defensible response. It commits to nothing except finding out, which is a commitment you can keep.
Three things not to say
“We are not required to test.” True, if you are provincially regulated. But it answers a question nobody asked — they asked whether the building has been tested, not whether you are obliged to. It reads as a brush-off and it tends to escalate rather than settle things.
“We will look into it.” Without a date, this is heard as no. It also leaves the question open indefinitely, which is worse for you than a clear answer either way.
“The building is fine.” Do not say this unless you have a laboratory result. Radon cannot be seen, smelled or inferred from a building's age, condition or ventilation, and a reassurance that later turns out to be wrong is far more damaging than admitting you did not know.
Step 4: decide whether to test
Here is the practical case, which has very little to do with regulation.
Testing is cheap relative to the alternative. Not the alternative of a fine — the alternative of the conversation continuing for months, being raised at every committee meeting, and eventually being asked about by someone whose good opinion matters to you.
Most buildings test low. The likeliest outcome by a wide margin is a result below the guideline, at which point you have a documented answer, the question is closed, and you have demonstrated that a raised concern gets taken seriously. That is worth something in its own right.
If it is high, you want to know now. Radon risk accumulates with exposure over time. A building above the guideline has been that way for years and will continue to be until someone measures it. Mitigation is usually a one-day job and typically reduces levels by more than 80%.
And the measurement window is seasonal. A valid long-term test needs a minimum of 91 days, ideally during the heating season — roughly October to April. Deciding in February usually means starting in October, so a decision deferred by a quarter is in practice deferred by most of a year.
What testing actually involves
Less than people expect. Long-term detectors are passive: no power, no wiring, nothing to install. Someone places them, they sit for three months, they go to a laboratory.
The one thing worth knowing up front is that the number of detectors is driven by the number of occupied rooms in contact with the ground — rooms at the lowest level where someone spends four hours or more a day. Not floor area, not headcount. Health Canada's public buildings protocol calls for one detector in each such room, one per 200 m² in larger open areas, and quality-control detectors in addition.
So a ground floor with twelve occupied rooms is roughly thirteen detectors plus QC, not one. A single reading for a whole building is not a compliant measurement and will not settle the question.
Detail: how commercial radon testing works. Our Canada radon map shows measured results by area, which is useful for prioritising buildings — regional data indicates probability, never a result for a specific building.
Step 5: if you have more buildings than one season allows
Do not treat this as all-or-nothing. A documented, risk-ranked, phased plan is a recognised approach: prioritise the buildings most likely to be affected, record why you ranked them that way, schedule the remainder, and be able to show progress.
For a committee, “we are testing these four this winter and the rest next year, and here is the reasoning” is a far better answer than either “we are testing everything” (which you may not deliver) or “we are not testing” (which does not close the question).
See how to risk-rank a building portfolio and how phased compliance works.
Step 6: if you need to get it funded
If the decision is not yours alone, the argument has been assembled: the radon business case, with the obligation, the evidence, the cost drivers and a memo you can adapt. There is a PDF version written to be forwarded to a budget holder.
What if the person who asked is not an employee?
A tenant. If you are the landlord, your position depends on the province and on the lease — see radon for landlords and property managers. If you are the tenant employer, the duty to your own staff sits with you regardless of who owns the building, though you will need the landlord's cooperation for access and for any remediation.
A parent, at a school or daycare. Mostly provincial, with some specific requirements — see radon in workplaces, schools and daycares.
An insurer, purchaser or client. Commercial rather than regulatory, and usually the fastest to resolve, because there is a named counterparty who wants a specific document.
Common questions
Are we legally required to test for radon?
If you are federally regulated, a 200 Bq/m³ annual-average exposure limit applies from 30 January 2027, and an annual average cannot be demonstrated without measuring. If you are provincially regulated, no numeric radon limit applies anywhere in Canada — but the general duty to take reasonable precautions against recognised hazards does.
Can we just say we are not required to?
You can, and it is accurate for provincial employers. It also tends not to end the conversation, because it answers a different question from the one that was asked. A short answer that commits to finding out, with a date, usually settles it better.
What if we test and the result is high?
Health Canada’s Guide for Radon Measurements in Public Buildings sets the remediation timeframes for public buildings: within two years for results between 200 and 600 Bq/m³, and within one year above 600 Bq/m³ — and the higher the concentration, the sooner action should be taken. (Health Canada’s guidance for homes differs: corrective action within one year above 200 Bq/m³.) Mitigation is usually a one-day job and typically reduces levels by more than 80%. You would then verify with a follow-up test. See what a borderline result means.
Does one test cover the building?
No. Health Canada's protocol for public buildings requires a detector in each occupied room in contact with the ground, plus quality-control detectors. A single reading will not close the question and will not survive scrutiny.
Do we need a certified professional?
Not necessarily. The federal regulation requires a qualified person, defined by knowledge, training and experience rather than by any specific credential, and contains no requirement for C-NRPP certification. Health Canada's guidance is that a certified professional would ideally be involved in the measurement strategy. See the qualified person question.
How long before we have an answer?
A minimum of three months of measurement, plus laboratory turnaround. Realistically, detectors placed in the autumn produce results in the spring.
If you want a number before you commit to anything
The most useful thing at this stage is usually a costed scope, so you can answer the question with something specific rather than a promise.
Email support@radontest.ca with the number of buildings and a rough count of occupied ground-contact rooms in each. We will come back with a detector count and a costed scope you can take to a committee or a budget holder. If a phased approach makes more sense for the number of buildings involved, we will say so.
We supply long-term detectors listed under the Canadian National Radon Proficiency Program, analysed by a C-NRPP-certified, ISO 17025-accredited laboratory — the combination Health Canada advises people to look for — and we handle logistics, chain of custody and the assembled record. We are listed by Take Action on Radon and are members of CARST. We do not perform mitigation, so we have no financial interest in what your results say.
RadonTest.ca may be able to help. And if all you need today is the detector arithmetic so you can give your committee a real answer, ask for that — we will send it without a sales process attached.
Read next
Which rules apply to your workplace · Workplace radon rules by province · The radon business case · How commercial radon testing works · The guide your staff may have read
RadonTest.ca provides testing logistics and laboratory submission. We do not perform radon mitigation and we do not interpret health risk — Health Canada is the health authority on radon in Canada. This page describes publicly available regulatory information and is not legal advice; obligations vary by jurisdiction and by circumstance.
Sources
Canada Gazette, Part II, Vol. 160, No. 3 — SOR/2026-10; Canada Occupational Health and Safety Regulations (SOR/86-304), ss. 10.4, 10.26; Canada Labour Code, Part II; Health Canada, Guide for Radon Measurements in Public Buildings; Health Canada, Canadian radon guideline; International Agency for Research on Cancer, Monograph Vol. 100D; C-NRPP.