Commercial Radon Testing in Canada: Process, Detector Counts and Cost

In Canada, commercial radon testing means measuring radon in a workplace or public building — an office, warehouse, school, daycare, care facility or municipal building — following Health Canada's Guide for Radon Measurements in Public Buildings. It is a different exercise from testing a house: more detectors, stricter placement rules, added quality control, and a written record that has to stand up years later.

This guide covers what the process actually involves, how many detectors a building needs, what it costs in the Canadian market, and how managing testing in-house compares with hiring a consultant.

TL;DR: Commercial radon testing uses long-term detectors (minimum three months, during the heating season) in every occupied ground-contact room, one per 200 m² in larger rooms, plus roughly 10% duplicates for quality control. Two delivery models exist: hire a consultant to place and interpret, or manage placement in-house using an accredited laboratory. Both are legitimate under Health Canada's guidance. Cost differs by roughly an order of magnitude.

What the protocol requires

Health Canada's public-buildings guide sets out the method. The essentials:

• Duration. A minimum of three months, conducted during the heating season. Short-term measurements are explicitly not acceptable for deciding whether remediation is needed.
• Coverage. Every occupied room with floors or walls in direct contact with the ground or a crawl space. If that level has no occupied rooms, every occupied room on the first occupied level above, until the building footprint is covered.
• Density. One detector in rooms under 200 m² (2,153 ft²); one detector per 200 m² in larger rooms.
• What counts as a room. A space enclosed by walls reaching the ceiling. A cubicle farm is one room, not twenty. Only rooms occupied more than four hours a day need testing.
• Quality control. Duplicate detectors at 10% of locations (max 25/month) and roughly 5% blanks — additional detectors beyond the floor-plan count. The first detector deployed should be a duplicate. Spikes, where detectors are exposed to a known concentration in an accredited chamber, are a laboratory-side control rather than detectors placed in your building.
• Placement. 0.5–2 m from the floor, at least 30 cm from an exterior wall, 10 cm clear of surrounding objects, away from HVAC currents, heat and direct sunlight. Never in bathrooms, kitchens, storage areas or indoor parking levels.
• Devices. C-NRPP-approved long-term devices — typically alpha track detectors — analyzed by a laboratory.

How many detectors will a building need?

These are illustrations, not a substitute for walking the floor plan. The variable that drives cost is the number of occupied ground-contact rooms — not the building's total square footage or its number of employees.

Two ways to get it done

Consultant-led testing

An environmental or occupational hygiene firm scopes the building, places detectors, retrieves them, arranges analysis and issues an interpretive report, often with a C-NRPP Measurement Professional involved. This is the right model for complex buildings, buildings where ventilation varies sharply between occupied and unoccupied hours, situations where a third-party professional opinion is needed for legal or insurance reasons, or where results are likely to be contested.

Market context: publicly disclosed federal contracts for radon testing services at government facilities have run from roughly $12,000 to over $50,000 per engagement, depending on the number of buildings and the scope of reporting. Smaller single-building commercial engagements are generally quoted in the low thousands.

Managed in-house testing

The employer places C-NRPP-approved long-term detectors itself, following the guide's placement rules, and returns them to an accredited laboratory for analysis. Health Canada's guidance describes the protocol in enough detail for a facilities or health-and-safety lead to follow it, and the guide states that a C-NRPP Measurement Professional's involvement in strategy is ideal rather than mandatory. This model suits straightforward buildings, multi-site organizations testing many similar locations, and organizations with in-house facilities staff.

Cost here is essentially detectors plus laboratory analysis plus shipping, so it scales with detector count rather than consultant time — typically an order of magnitude less for a simple building. The trade-off is real: the employer owns the placement decisions, the record-keeping and the consequences of getting either wrong. Buildings with complex ventilation, mixed occupancy schedules, results likely to be contested, or any situation where a third-party professional opinion may be needed are better served by a consultant. If in doubt, engage a C-NRPP Measurement Professional — Health Canada's guide states that their involvement in measurement strategy is ideal.

What your record has to contain

This is the part most buyers discover late. The regulations set out the content of an air sampling test record, and a laboratory certificate does not meet it on its own. The record includes:

• the date, time and location of the test
• the substance tested for
• the sampling and testing method used
• the result obtained
• the name and occupation of the person who made the test

The lab supplies the result. Everything else — where each detector went, when it was placed and retrieved, the method followed, and who did it — is field information you have to capture at the time and keep. Reconstructing it later from memory is exactly the situation the record exists to prevent. Note too that the employer's hazardous-substance register covers substances handled by contractors in the workplace, not only by its own staff.

What to do with the results

Who verifies the fix

One point worth thinking about before you engage anyone. Mitigation involves three distinct roles: measuring the building, designing and installing the remedy, and then verifying that the remedy worked. Those can all be performed by the same firm, and often are.

Health Canada takes a position on this, and it is more direct than most building owners realise. Its Radon — Reduction Guide for Canadians states: "To avoid conflict of interest, the test should not be performed by the company that installed the radon mitigation system."

That guidance appears in Health Canada's residential publication; the public-buildings guide does not address post-mitigation verification at all, so Canada has no workplace-specific standard on the point. The reasoning transfers, but an employer applying it should record that it is doing so. It is guidance rather than law, and for complex buildings a single accountable party has real advantages. But it is Health Canada's stated recommendation, and the reasoning is the same as in any other trade: a building inspection is not usually performed by the builder. If a result ever has to be defended to a regulator, an auditor, an insurer or a health and safety committee, independence of the verification step is one of the first things a careful reader will look for. Full sequence and timings: post-mitigation radon verification.

Health Canada's method for confirming a fix is a short-term test at least 24 hours after mitigation is complete, followed by a long-term test during the next heating season, both in the same locations as the original measurement.

Interpreting the result

If the long-term average is below 200 Bq/m³, no further measurement is required — though Health Canada notes that levels vary year to year and that building owners should consider mitigation where results approach the guideline. Common practice is to treat 150–200 Bq/m³ as a watch band: retest and monitor rather than close the file, on the reasoning that 200 is an action level rather than a safety threshold, that results move year to year, and that a measurement near the guideline carries uncertainty that may straddle it. Above 200 Bq/m³, Health Canada recommends remediation within two years, and within one year above 600 Bq/m³, carried out by certified mitigation professionals, with retesting to confirm the reduction.

Records matter more in commercial testing than residential. The Canada Occupational Health and Safety Regulations already require the qualified person's hazard investigation report to be kept 30 years from signature (s. 10.6); the 2026 amendments bring air sampling record retention into line. Health Canada's guide sets no fixed retest interval for buildings that tested below the guideline. The trigger is change: major renovation, modified or rebalanced HVAC, altered airflow, a change in occupancy or in how rooms on the lowest occupied level are used, or anything affecting how the building meets the soil. Mitigated buildings are retested after the work and rechecked every five years. That interval comes from Health Canada's residential guidance; the public-buildings guide sets no post-mitigation retest interval, so it is applied to workplaces by extension rather than by rule. Many organisations also adopt a periodic review interval of around ten years as prudent practice — that is practice, not a requirement. Whatever model you choose, keep the detector locations, dates, serial numbers, laboratory certificates and any follow-up actions in a form that will still make sense to someone reading them a decade from now.

Beyond a single test: what a radon management programme contains

For a single building, a test and a record are the job. For an organisation with a portfolio, the emerging expectation — and the framing the Labour Program responds to for phased compliance — is a programme rather than a one-off measurement. In practice it has six parts:

1. Policy and accountability. A written radon policy that names an owner and treats radon as a managed hazard, with a change-management process so it survives staff turnover.
2. Inventory and risk ranking. Every applicable building listed and weighted into risk categories. This is what makes a phased approach defensible — see below for how the weighting is built.
3. Qualified testing. Testing carried out under s. 10.4 by a qualified person, using approved devices and Health Canada's protocol.
4. Defensible records. Dates, locations, methods, detection limits, laboratory qualifications, results and the person who performed the test — retained 30 years.
5. Mitigation and verification. Where results exceed 200 Bq/m³: documented mitigation, retesting to confirm the reduction, and ongoing monitoring.
6. Retesting and communication. A recurring retest schedule, worker notification, and health and safety committee engagement.

A programme turns a one-time test into ongoing, provable compliance. Note what that list is mostly made of: five of the six elements are documentation, scheduling and record management. Only the testing element involves fieldwork, and even there the regulation asks for a qualified person rather than an attendance.

How to risk-rank a portfolio

If you hold more than a handful of buildings, the first real question is not "how do we test" but "which buildings first." A defensible ranking weighs five factors:

Weighting these into a single score lets you sequence a portfolio and, importantly, show your work. Full method, with the evidence behind each factor: how to risk-rank a building portfolio. A ranking you can explain is what turns "we could not test everything in one season" into a documented prioritisation the regulator can accept.

Two cautions. A ranking predicts likelihood, not results — buildings on the same street routinely test differently, so a low rank is a scheduling decision, not a conclusion about the building. And the ranking is only as good as the inventory beneath it: buildings you have forgotten you occupy cannot be ranked.

One point worth getting right on "qualified"

You will see s. 10.4 cited alongside the statement that testing must be done by a C-NRPP certified professional. Section 10.4 does not say that. It requires the employer to appoint a "qualified person" — defined by knowledge, training and experience — to carry out an investigation. C-NRPP certification is a well-recognised way of demonstrating that competence, and for complex buildings it is the sensible choice. It is not a statutory requirement, and an employer should understand the difference between what the regulation requires and what a service provider recommends. Full treatment: does a certified professional have to do the testing?

Ventilation drives both the result and the retest question — see radon, HVAC and ventilation.

Common questions

Is commercial radon testing mandatory in Canada?

For federally regulated employers, a 200 Bq/m³ annual-average exposure limit takes effect January 30, 2027, and it cannot be demonstrated without measurement. For provincially regulated employers there is no radon-specific limit, but the general duty to protect workers from recognized hazards applies in every province. See which rules apply to your workplace.

Can we use a consumer radon monitor instead?

Not for establishing where a building stands against an annual-average threshold. Health Canada's public-buildings guide states short-term measurements are not acceptable for assessing the initial need for remediation. Continuous monitors have a defined supplementary role where ventilation differs between occupied and unoccupied hours, following a long-term test.

When should testing start?

Detectors need at least 91 days during the heating season. Counting back from January 30, 2027 puts placement in early November 2026 — see the compliance timeline for the full arithmetic.

Do we need to test every building we occupy?

Yes. Radon varies enormously between buildings, including neighbouring buildings on the same street, because it depends on the soil beneath and the structure's interaction with it. There is no way to infer one building's level from another's.

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.

Read next

Landlords and property managers · Hospitals, care facilities and correctional centres · The legal brief

Sources

Health Canada, Guide for Radon Measurements in Public Buildings (H129-120/2022E); Health Canada, Canadian radon guideline; Canada Gazette, Part II, Vol. 160, No. 3 (SOR/2026-10); Employment and Social Development Canada, Introducing amendments to regulations under Part II of the Canada Labour Code; Canadian Centre for Occupational Health and Safety, Radon in Buildings; Government of Canada proactive disclosure of contracts over $10,000.