A note before you read. This article is general information for Canadian homeowners — not medical, legal, or financial advice. Radon results are reported against Health Canada's guideline of 200 Bq/m³. RadonTest.ca coordinates kit logistics and sample submission only; we do not interpret your results or assess your health. All analysis is performed independently by a C-NRPP-certified laboratory.
Quick answer
Two different devices get called a "radon detector", and they answer different questions. An alpha-track dosimeter is a small passive device that sits for 91+ days and is analysed by a laboratory — it produces the long-term average Health Canada's 200 Bq/m³ guideline is written against. A digital continuous monitor is an electronic device you buy once that shows changing readings on a screen — useful for watching trends, not for the decision.
If you want one number to act on, you want the dosimeter. If you want to watch what your house does day to day, you want the monitor. Plenty of people end up with both, in that order.
The two device families
| Alpha-track dosimeter | Digital continuous monitor | |
|---|---|---|
| How it works | Passive plastic film; alpha particles leave tracks the lab counts | Electronic sensor sampling the air continuously |
| Where the result comes from | A laboratory, after you mail it back | The device's own screen or app |
| Best for | The official long-term average | Trends, before/after checks, curiosity |
| Typical duration | 91+ days | Ongoing, indefinitely |
| Needs a lab? | Yes | No |
| Answers the Health Canada question? | Yes | Not on its own |
The distinction that matters is not price or sophistication — it is who produces the result. A dosimeter's number comes from an accredited laboratory that has calibrated its analysis. A consumer monitor's number comes from the device in your hand.
Why the guideline points to a long-term dosimeter
Health Canada's guideline is 200 Bq/m³ as an annual average, and that phrasing is doing real work. Radon moves constantly — with weather, with the heating season, with whether a window has been open. Any single day can be well above or well below a home's true typical level.
That is why the measurement protocol asks for at least 91 days, on the lowest lived-in level. A long-term dosimeter is built to integrate that whole period into one figure. A short test, however good the instrument, mostly captures the conditions of the days it ran.
Health Canada is explicit that short-term tests are "not appropriate for informing mitigation decisions". They have a role — checking quickly whether a mitigation system is doing its job, for instance — but they are always confirmed by a long test.
Where digital monitors genuinely help
None of that makes a monitor pointless. A continuous monitor is good at things a dosimeter cannot do:
- Seeing the pattern — how much your level swings between seasons, or between a closed-up week and an open-window one
- Before and after — watching a mitigation system take effect in real time
- Ongoing reassurance — a persistent readout in a basement office or bedroom
What it should not be asked to do is settle the question of whether your home is above or below the guideline. For a device-by-device look at what is available in Canada, see the best continuous radon monitors, and for the two approaches side by side, long-term test vs digital monitor.
What "C-NRPP-listed" means when you are shopping
You will see C-NRPP mentioned around radon devices, and it is worth being precise about it, because the term is often stretched in marketing.
C-NRPP applies to the detector, the laboratory, and the professional — not to a retailer or a brand as a whole. So a detector can be C-NRPP-listed, and a lab can be C-NRPP-certified, and a mitigation contractor can be C-NRPP-certified. A company describing itself as "C-NRPP certified" without reference to any of those is telling you less than it appears to.
There is also no such thing as a "Health Canada approved" radon device. Health Canada publishes the guideline and the measurement protocol; it does not certify consumer products. We unpack that term in full in what “Health Canada approved” really means for radon detectors.
Choosing, in practice
Work backwards from the question you actually have:
- "Is my home above or below 200 Bq/m³?" — a long-term alpha-track dosimeter, 91+ days, lowest lived-in level, analysed by a C-NRPP-certified lab.
- "My test came back high — is the fix working?" — a monitor is genuinely useful here, alongside a follow-up long-term test to confirm.
- "I want to understand my house's rhythm." — a monitor, with the expectation that the numbers will bounce around.
Whatever you use, placement decides whether the result means anything: clear air, away from vents, drafts, windows and exterior walls. Where to place a radon test kit has the details, and how to read your results covers what to do with the number once it arrives.
FAQ
What is the difference between a radon detector and a radon dosimeter? In Canadian usage a dosimeter is the passive alpha-track device that records exposure over months and is analysed by a lab. "Detector" is used loosely for both that and electronic monitors, which is why the two get confused.
Which type does Health Canada's guideline require? The guideline is an annual average, so it points to a long-term measurement of at least 91 days on the lowest lived-in level. That is what an alpha-track dosimeter provides.
Are digital radon monitors accurate? Good ones track real changes well, and they are useful for trends and for confirming a mitigation system is working. They are not a substitute for a long-term lab-analysed test when the question is whether your home is above the guideline.
Do I need a device that is C-NRPP certified? C-NRPP applies to the detector, the analysing laboratory and the professional — not to companies in general. For a long-term test, what matters is that the detector is C-NRPP-listed and the lab is C-NRPP-certified.
Can I reuse an alpha-track dosimeter? No. It is a single-use device: the film records the whole exposure period and is consumed by the laboratory analysis.
How long does a radon test have to run? At least 91 days. Shorter tests are not used to decide about mitigation, because they mostly reflect the conditions during the days they ran.
Sources
- Health Canada — Guide for radon measurements in residential dwellings: https://www.canada.ca/en/health-canada/services/publications/health-risks-safety/guide-radon-measurements-residential-dwellings.html
- Health Canada — Radon: https://www.canada.ca/en/health-canada/services/health-risks-safety/radiation/radon.html
- Health Canada — Government of Canada radon guideline: https://www.canada.ca/en/health-canada/services/health-risks-safety/radiation/radon/government-canada-radon-guideline.html
- Canadian National Radon Proficiency Program (C-NRPP): https://c-nrpp.ca/
Ready to get the number that counts?
Our kit is the long-term route: a C-NRPP-listed alpha-track detector, prepaid analysis at a C-NRPP-certified Canadian laboratory, return shipping, and a Certificate of Analysis — with reminders so the test actually finishes and comes back.