A note before you read. This is general consumer information for Canadian homeowners, buyers, sellers, and renters, drawn from publicly available Health Canada, World Health Organization, and peer-reviewed sources. It is not medical, legal, or warranty advice. Radon 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
- There is no radon level that is risk-free. Health Canada is explicit: radon is a known cause of lung cancer at any concentration, so no level can be called "risk-free." Lower is always better.
- Canada's guideline is 200 becquerels per cubic metre (Bq/m³), measured as an annual average. It is a health-based action guideline — the point at which Health Canada recommends fixing your home — not a hard line between "risk-free" and "high-risk."
- If your long-term result is at or above 200 Bq/m³, Health Canada recommends taking corrective action within one year — and sooner the higher the level. Below 200, no action is required, but the risk is not zero.
- Other bodies use lower reference levels. The World Health Organization references 100 Bq/m³, and the US EPA acts at 148 Bq/m³ (4 pCi/L). Canada's 200 is among the higher national guidelines.
- "Average" is not "acceptable." Health Canada estimates 1 in 5 Canadian homes have high radon levels. A separate 2024 study by Evict Radon / University of Calgary put about 18% of homes above 200 Bq/m³, with a national geometric-mean concentration around 84.7 Bq/m³. A typical home's reading tells you nothing about whether your own home is fine.
- Your result is a number on a spectrum, not a pass/fail. What's "acceptable" below the guideline is ultimately the homeowner's judgment — some households, especially where someone smokes, choose to act toward the WHO's more protective 100 Bq/m³.
- The only way to know your level is to test — a long-term test of at least 91 days, ideally over the heating season.
Is there a "risk-free" level of radon?
The honest answer, and the one Health Canada gives, is no — there is no level of radon that is completely risk-free. Radon is a radioactive gas, and the radiation dose it delivers to your lungs scales with how much you breathe in over time. Reduce the concentration and you reduce the risk; there is no threshold below which the risk suddenly drops to zero.
This is why you'll rarely see a careful source — Health Canada, the World Health Organization, or a reputable testing company — call any radon reading "risk-free." The word that fits is "lower." Lower is always better, and the guideline exists to mark the point where action becomes clearly worthwhile, not to certify everything beneath it as harmless.
That doesn't mean a low reading is cause for worry. It means radon risk is proportionate and long-term, not acute. There are no symptoms and no immediate danger at any household level; the concern is cumulative lifetime exposure. So the practical framing is: find out your number, act on it if it's at or above the guideline, and decide for yourself how far below the guideline you want to go.
The Canadian guideline: 200 Bq/m³
Canada's national guideline is 200 becquerels per cubic metre (Bq/m³), measured as an annual average in a normally occupied area of the home. Two things about that definition matter:
- It's a health-based action guideline, not a legal limit for private homes and not a bright line between "risk-free" and "dangerous." It's the level at which Health Canada says the benefit of fixing your home clearly outweighs the cost and effort. A home at 210 Bq/m³ is not meaningfully more hazardous than one at 190; the guideline simply has to be drawn somewhere, and Canada drew it at 200.
- It's an annual average, because radon swings hour to hour and season to season. A single afternoon's reading means little. What reflects your real exposure — and what the guideline is written against — is a long-term average over at least 91 days, which is why Health Canada recommends a long-term test, ideally during the heating season when homes are closed up.
Health Canada's guidance around the number is straightforward:
- At or above 200 Bq/m³: take corrective action to reduce the level, within one year — and sooner the higher the result. A home in the thousands warrants quicker action than one just over the line.
- Below 200 Bq/m³: no corrective action is recommended. But, again, no level is risk-free, so some households choose to reduce a moderate reading further anyway.
For a fuller walkthrough of where 200 came from and how it's applied, see our explainer on how the Health Canada, WHO, and US thresholds compare.
How 200 compares: WHO 100, US EPA 148
Canada's 200 Bq/m³ is on the higher end of the world's radon reference levels. For context:
- World Health Organization — 100 Bq/m³. The WHO recommends a reference level of 100 Bq/m³, and suggests countries that can't reach it should not exceed 300. Canada's guideline sits between those two markers.
- United States (EPA) — 148 Bq/m³ (4 pCi/L). The US action level is most often written in different units — picocuries per litre — where 4 pCi/L equals about 148 Bq/m³.
So the same physical home could be "above the action level" in the US, "above the reference level" under the WHO, and still "below the guideline" in Canada. None of these numbers is the "true" risk-free level — there isn't one. They're different judgment calls about where action becomes worthwhile, balancing health protection against what's practical to achieve at a national scale.
The deeper comparison — including why Canada lowered its guideline from 800 to 200 in 2007, and what each body's number is actually based on — is covered in our dedicated article on radon guideline levels: Health Canada vs WHO vs USA.
What's a "normal" or average radon level in Canada?
People often search for a "normal" radon level hoping for a benchmark to measure their home against. It's worth being clear up front: a national average can't tell you whether your own home is fine. Two houses next door to each other can read very differently depending on soil, foundation, and ventilation. With that caveat, here is what the Canadian data shows.
- Health Canada's Cross-Canada Survey of Radon Concentrations in Homes (data collected 2009–2011, published 2012) found that about 6.9% of Canadians were living in homes at or above the 200 Bq/m³ guideline — roughly 1 in 14 at the time. Health Canada's current public-facing figure, reflecting the many homes tested since, is that 1 in 5 Canadian homes have high radon levels.
- The 2024 Cross-Canada Radon Survey, led by Evict Radon and the University of Calgary, drew on tens of thousands of long-term household readings and found about 18% of homes at or above 200 Bq/m³ — close to Health Canada's "1 in 5" headline — with a national geometric-mean concentration of about 84.7 Bq/m³. (This 18% figure is the Evict Radon / University of Calgary study, not a Health Canada survey result — the two are often confused.)
A note on that geometric mean: it means a "typical" Canadian home reads somewhere in the neighbourhood of 85 Bq/m³ — comfortably below the 200 guideline, but well above zero, and above the WHO's 100 reference level once you include the large share of homes that sit higher.
Here's the crucial point hiding in those numbers: "average" is not "acceptable." An average exists precisely because real homes are scattered widely on either side of it. A typical home being around 85 Bq/m³ is no reassurance to the roughly one in five homes that are above 200. The only number that's relevant to your health is your home's measured level. For how the averages break down geographically, see radon levels by province: what the Canadian data shows.
What your number means
Because radon exists on a spectrum, it helps to think in ranges rather than a single pass/fail line. Health Canada's recommendations key off the 200 Bq/m³ guideline:
- At or above 200 Bq/m³ — Health Canada recommends taking corrective action within one year, and sooner the higher the level. This is a solvable problem; see what to do if your radon level is above 200 Bq/m³.
- Below 200 Bq/m³ — no corrective action is recommended by Health Canada. The risk at these levels is smaller, though not zero. Some households — particularly those with a smoker, or anyone who simply wants to minimize exposure — choose to act toward the WHO's 100 Bq/m³ reference level.
Your result is a concentration, not a verdict. A plain-language walkthrough of what different result ranges mean, and what Health Canada recommends at each, is in our guide on how to read your radon test results.
One more thing worth knowing about why the level below the guideline still matters: because the great majority of Canadian homes sit below 200, a large share of all radon-related lung cancers actually arises from those many lower-level homes rather than from the smaller number of very high ones. That's the public-health logic behind "lower is always better," and behind some households' decision to reduce even a moderate reading.
So what should you accept?
Since there is no risk-free level, "what's acceptable" below the guideline is genuinely a personal decision — and a reasonable one to make deliberately rather than by default. A useful way to frame it:
- At or above 200 Bq/m³: this isn't really a matter of preference. Health Canada recommends acting within a year (sooner the higher), and the fix is well understood and usually affordable.
- Between roughly 100 and 200 Bq/m³: below the Canadian guideline but at or above the WHO's reference level. Health Canada doesn't require action here, but many people — especially smokers and former smokers, for whom radon and tobacco multiply each other's risk — choose to reduce it. Entirely your call.
- Below 100 Bq/m³: below both the Canadian guideline and the WHO reference level. Most people are comfortable here. It still isn't "zero risk," and retesting after major renovations or energy retrofits is still wise, but this is a level most homeowners reasonably accept.
The single most important step isn't choosing a personal threshold — it's getting a real number to choose against. Until you've tested, you're guessing.
Frequently asked questions
Is there a risk-free level of radon? No. Health Canada states there is no level of radon that is completely risk-free — radon can cause lung cancer at any concentration, so lower is always better. The 200 Bq/m³ guideline marks where action is clearly worthwhile, not a point below which radon is harmless.
What is an acceptable radon level in Canada? Health Canada's action guideline is 200 Bq/m³ (annual average). At or above it, the recommendation is to take corrective action within one year — sooner the higher the level. Below it, no action is required, but because no level is risk-free, what's "acceptable" beneath the guideline is the homeowner's choice; some act toward the WHO's 100 Bq/m³.
What is a normal or average radon level in Canada? The 2024 Evict Radon / University of Calgary study found a national geometric-mean concentration around 84.7 Bq/m³, with about 18% of homes at or above 200 Bq/m³. Health Canada's headline figure is that 1 in 5 Canadian homes have high radon. But an average can't tell you about your home — only a test can.
Is 100 Bq/m³ ok? Is 150? Is 250? There's no level that is risk-free, so none is "ok" in an absolute sense — but Health Canada only recommends corrective action at or above 200. So 100 and 150 are below the Canadian guideline (100 is the WHO's reference level, which some choose to act on); 250 is above the guideline, and Health Canada recommends fixing it within a year. In every case, lower is better.
Why does Canada use 200 when the WHO uses 100? Different bodies make different judgment calls about where action becomes worthwhile, balancing health protection against what's achievable at scale. The WHO references 100 Bq/m³ (and suggests not exceeding 300 where 100 isn't feasible); the US EPA acts at 148 Bq/m³ (4 pCi/L); Canada's guideline is 200. None is the "true risk-free level" — there isn't one. See our guideline comparison.
What's the difference between Bq/m³ and pCi/L? They're two units for the same thing. Canada and most of the world use becquerels per cubic metre (Bq/m³); the United States uses picocuries per litre (pCi/L). To convert: 1 pCi/L = 37 Bq/m³. So the US action level of 4 pCi/L is about 148 Bq/m³, and Canada's 200 Bq/m³ is about 5.4 pCi/L.
My result is below 200 — do I still need to do anything? Health Canada doesn't recommend mitigation below the guideline. It's still good practice to retest after renovations that affect your home's structure or ventilation, after energy retrofits (new windows, insulation, air sealing), or after excavation near the foundation, since those can change your level. If you ever install a mitigation system, retest every five years to confirm it's working.
How accurate does a test need to be to trust the number? Use a long-term test of at least 91 days, ideally over the heating season, with an alpha-track detector analysed by a C-NRPP-certified laboratory. Short-term snapshots aren't suitable for deciding whether to act, because radon varies so much day to day. Is radon actually worth worrying about? See is radon dangerous?
Find out your home's number
There's no "risk-free" radon level to aim for and no national average that can stand in for your own home's reading. The only way to know whether your home is at, above, or comfortably below the 200 Bq/m³ guideline is a long-term test of at least 91 days.
Order your RadonTest.ca kit → — lab analysis by a C-NRPP-certified laboratory (with an all-in-Canada analysis option), tracked shipping both ways, and your result delivered with clear Health Canada context.
Sources
- Health Canada — Government of Canada radon guideline (200 Bq/m³; corrective action within 1 year, sooner the higher; no risk-free level), modified 2025-09-24. https://radontest.ca/links/hc-guideline
- Health Canada — Radon: What you need to know ("1 in 5 homes have high radon"; risk framing), 2025 edition. https://radontest.ca/links/hc-what-you-need-to-know
- Health Canada — Reducing radon levels in your home (corrective action; C-NRPP), modified 2025-10-09. https://radontest.ca/links/hc-mitigation-guide
- Health Canada — Cross-Canada Survey of Radon Concentrations in Homes, Final Report (national ~6.9% above 200; survey methodology), 2012. https://www.canada.ca/en/health-canada/services/environmental-workplace-health/reports-publications/radiation/cross-canada-survey-radon-concentrations-homes-final-report-health-canada-2012.html
- Evict Radon / 2024 Cross-Canada Radon Survey, University of Calgary (about 18% of homes above 200 Bq/m³; national geometric mean ~84.7 Bq/m³). https://crosscanadaradon.ca/survey/
- World Health Organization — Radon and health fact sheet (100 Bq/m³ reference level; not exceeding 300; no known risk-free level). https://www.who.int/news-room/fact-sheets/detail/radon-and-health
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 World Health Organization, and the Evict Radon / University of Calgary study is summarized from the public sources listed above; confirm time-sensitive details with the responsible body.