Canada’s Radon Guideline Is Higher Than the WHO’s. What Homeowners Should Know.
If you’ve been reading about radon, you may have noticed something confusing.
In Canada, Health Canada recommends taking action when radon levels are above 200 Bq/m³.
The World Health Organization recommends a lower reference level of 100 Bq/m³.
So what should homeowners do if their home tests somewhere between 100 and 200?
The short answer: Canada’s current action level is still 200 Bq/m³, but lower is better. Health Canada also says there is no completely safe level of radon exposure and recommends reducing levels as much as reasonably possible.
Quick Answer: Canada vs. WHO Radon Guidelines
Canada’s current radon guideline is 200 Bq/m³. The World Health Organization recommends 100 Bq/m³ where possible.
If your home tests between 100 and 200 Bq/m³, it is below Canada’s current action level but above the WHO’s recommended level. That does not mean urgent action is automatically required, but it does mean the result is worth understanding.
Health Canada also says there is no completely safe level of radon exposure and recommends reducing levels as much as reasonably possible.
What Is Radon?
Radon is a naturally occurring radioactive gas that comes from the ground. It can enter homes through foundation cracks, sump pits, floor drains, gaps around pipes, and other openings in the basement floor or foundation.
You can’t see it or smell it, so radon testing is the only way to know your home’s level.
Long-term exposure to elevated radon is the leading cause of lung cancer in non-smokers.
What Is Canada’s Radon Guideline?
Health Canada’s current radon guideline is 200 Bq/m³. If the long-term average in your home is above that level, Health Canada recommends taking action to reduce it.
Canada’s guideline was last updated in 2007, when it was lowered from 800 Bq/m³ to 200 Bq/m³. According to recent CBC reporting, Health Canada does not currently plan to change the guideline and is focused on getting more Canadians to test their homes.
What Does the World Health Organization Recommend?
The World Health Organization recommends a lower reference level of 100 Bq/m³ where possible.
CBC reported that the WHO launched an international radon research project in 2005 and, by 2009, recommended that countries aim for a national reference level of 100 Bq/m³. Where that is not possible, the WHO says the chosen level should not exceed 300 Bq/m³.
This creates a grey area for homeowners whose results fall between 100 and 200 Bq/m³. For example, a reading of 150 Bq/m³ is below Canada’s action level, but above the WHO’s recommended level.
Does Below 200 Bq/m³ Mean There Is No Risk?
Not exactly.
Health Canada’s guideline tells homeowners when action is recommended, but it does not mean levels below 200 Bq/m³ are risk-free.
CBC reported that Health Canada emphasizes there is no safe level of radon exposure and encourages Canadians to reduce radon levels as much as possible.
The 200 Bq/m³ guideline is an action level. It is not a line between “safe” and “dangerous.”
FAQ: Why are Canada’s and WHO’s radon guidelines different?
The WHO’s 100 Bq/m³ reference level is more health-risk focused and recommends keeping levels as low as absolutely possible. Canada’s guidelines consider both health-risk and practical factors, including the cost and responsibility of mitigation for homeowners.
For homeowners, the key takeaway is simple: 200 Bq/m³ is Canada’s current action level, but lower radon levels are better for long-term health.
Why Do Some Researchers Want Canada’s Guideline Lowered?
Some researchers believe Canada should take another look at its radon guideline, especially now that mitigation systems can often reduce radon levels significantly.
CBC reported that long-term indoor radon exposure is clearly linked to lung cancer, and that risk rises with higher radon exposure rather than only becoming a concern above one specific number.
The same CBC article reported that the 2024 Cross Canada Radon Survey found 20% of detached homes in Canada may have radon levels above 200 Bq/m³, while another 26% fall between 100 and 199 Bq/m³. That means close to half of detached homes could be above the WHO’s recommended level.
What If Your Home Tests Between 100 and 200 Bq/m³?
A result between 100 and 200 Bq/m³ does not automatically mean urgent action is required. For many homeowners, it becomes a personal decision based on:
how close the level is to 200
whether children or other family members spend a lot of time in lower levels of the home
whether the basement is used as a bedroom, office, gym, or playroom
whether renovations are planned
whether reducing levels is practical and affordable
At Radon86, we recommend mitigation at Health Canada’s current guideline of 200 Bq/m³. But when mitigation is done, the goal is always to reduce levels as low as reasonably possible.
Can Radon Levels Be Reduced Below 200?
Yes. In many homes, radon mitigation can reduce levels significantly.
CBC reported that Health Canada says modern mitigation work can reduce indoor radon levels by more than 80% when done correctly.
Most mitigation systems use a pipe and fan to draw radon from beneath the home and vent it safely outside before it builds up indoors.
What Should Winnipeg Homeowners Do?
If you live in Winnipeg or elsewhere in Manitoba, testing is the first step.
Manitoba has higher radon levels than many parts of Canada, and about 1 in 4 homes in Manitoba test above Health Canada’s recommended guideline.
Homes on the same street can have very different radon readings, so you can’t rely on your neighbourhood, your neighbour’s result, or the age of your home. We offer a free 15-minute on-the-spot radon test. Call or text us at 204-807-1340 to set up a good time for a visit.
The Bottom Line
Canada’s current radon guideline is 200 Bq/m³. The WHO recommends 100 Bq/m³.
For homeowners, the key takeaway is simple: 200 is Canada’s action level, but lower radon levels are better for long-term health.
That does not mean every home between 100 and 200 Bq/m³ needs immediate mitigation. But it does mean radon risk is not all-or-nothing.
If you’re in Winnipeg and want to understand your radon levels, Radon86 offers radon testing and mitigation services. We can help you understand your results and explain your options if levels are elevated.
Give us a call at 204-807-1340 or contact us here.