You opened the envelope — or refreshed the online portal — and there it is. Your radon result is sitting just above 200 Bq/m³. Maybe 215. Maybe 240. Close enough to the guideline that you’re not sure whether to be worried, but high enough that you can’t quite put it out of your mind.
This is one of the most common situations radon professionals encounter, and it’s also the one where homeowners most deserve a calm, honest conversation — not a sales pitch dressed up as urgency.
So let’s have that conversation.
First: Take a Breath
Health Canada’s radon guideline is 200 Bq/m³. If your long-term average is above that threshold, corrective action is recommended — and the guidance is clear that acting sooner makes sense as levels climb higher. But “just over” is a genuinely different situation than “well above,” and homeowners at the borderline deserve more nuance than a simple “you need to mitigate immediately.”
Radon is a real health consideration. It’s the leading environmental cause of lung cancer in Canada after smoking, and the risk is cumulative — meaning it’s about how much radon you’re breathing, over how long a period. That context matters for decisions. But it also means that a borderline result, properly understood, rarely demands a same-week installation. It demands a clear-headed look at what you’re actually dealing with.
Step 1: Make Sure You're Using the Right Kind of Test
Before anything else, it’s worth asking a simple question: what kind of test produced this result?
If your reading came from a short-term test — typically two to seven days — treat it as a screening signal rather than a final verdict. Short-term tests are useful. They can flag a potential problem, inform a real-estate timeline, or give you a rough sense of whether further investigation is warranted. But they capture a narrow window of radon behaviour in a home that’s constantly changing.
Health Canada is explicit on this point: short-term measurements should be confirmed with a follow-up long-term measurement before major decisions are made.
A long-term test — a minimum of three months, ideally conducted during the fall and winter when homes are closed up and radon concentrations tend to be at their highest — gives you the most reliable basis for a mitigation decision. If your just-over-200 result came from a short-term test, the most defensible next step is often simply to run a long-term test before committing to anything else.
Radon levels in Canadian homes can vary by a factor of two or more between seasons, between floors, and even between different areas of the same basement. A single data point, however useful, is rarely the whole story. You can learn more about the radon testing process and what a proper long-term measurement involves before deciding on a path forward.
Step 2: Ask One Simple Question — What Is My Actual Exposure?
Radon risk is fundamentally about two things: level and time. A home with a reading of 220 Bq/m³ where the basement is an unfinished storage room that no one enters is a meaningfully different situation than a home with the same reading where someone sleeps in a basement bedroom seven nights a week.
This doesn’t mean exposure in a less-occupied basement is irrelevant — radon mixes into the whole-home air over time, and a lower level throughout the house still contributes to cumulative exposure. But occupancy patterns are a legitimate part of the decision framework, and a good advisor will ask about them.
Practical questions worth thinking through:
- How is the basement or lower level used day-to-day?
- Who spends time there, and roughly how many hours per day?
- Is there a sleeping area, home office, or secondary suite in the lower level?
- Are you looking at a stable long-term average, or is this result still preliminary?
The answers don’t change the guideline — 200 Bq/m³ is the threshold regardless of how you use the space. But they do meaningfully inform how urgently mitigation belongs on your priority list, and what kind of staged approach might make sense while you gather more information.
Step 3: Understand What "Staged Options" Can Look Like
Here is Royal Radon’s plain-language position for borderline results — what they call their Near-Threshold Policy for Calgary and area:
If a home is just over 200 Bq/m³, Royal Radon will always present a confirmatory long-term testing plan, at least one staged or lower-cost option where appropriate, and a clear explanation of when full mitigation becomes the sensible move.
That framing — no panic, no pressure, just a plan you can defend — is worth holding onto as a benchmark when you talk to any radon professional. A contractor who responds to a borderline result with immediate urgency and a full installation quote, without first discussing test type, occupancy, or staged alternatives, is worth approaching carefully.
What might staged options look like in practice? They vary by home and situation, but the general principle is that not every just-over-200 result requires an immediate full-system installation. Sometimes the right first step is a confirmatory long-term test. Sometimes it’s addressing an obvious and inexpensive entry point — a poorly sealed sump lid, for example — and re-testing. Sometimes it’s simply committing to a timeline: if the long-term average confirms the short-term result, mitigation happens in the spring. The specifics depend on the home and the homeowner’s situation, but the point is that options exist, and a good advisor will walk you through them rather than defaulting to the most expensive immediate path.
Step 4: Know When Mitigation Becomes the Straightforward Call
Staged thinking has its place, but so does clarity about when the straightforward answer is simply: mitigate.
Mitigation becomes increasingly easy to justify when:
- There’s heavy basement use — a bedroom, a home office, a suite. If someone is spending significant time in the lower level, the cumulative exposure argument shifts meaningfully toward acting sooner.
- You’re planning renovations anyway. Radon mitigation often involves accessing the sub-slab and routing pipe through mechanical spaces. If you’re already planning work that touches those areas, doing the mitigation alongside it is simply efficient.
- Levels are well above the guideline. Health Canada’s guidance notes that the urgency of corrective action increases with the level. A reading of 600 Bq/m³ is a different conversation than 210 Bq/m³, even if both are technically “above guideline.”
- You’ve already confirmed the result with a long-term test. If you’ve done the due diligence of a proper long-term measurement and it comes back above 200, the confirmation itself is a meaningful reason to move forward.
None of this is meant to be pressure — it’s meant to be a framework. The goal is for you to be able to look at your specific situation and understand why a given course of action makes sense, rather than simply taking a contractor’s word for it.
Step 5: If You Do Mitigate, Verification Is Part of the Job
A mitigation installation without a clear verification plan is, as one Royal Radon technician put it plainly: hope with PVC.
Health Canada’s guidance emphasizes the use of qualified, certified professionals — C-NRPP certification is the recognized Canadian standard — and the importance of testing to confirm that a system is performing as intended. Installation day is not the end of the process. It’s the middle.
When a mitigation project is properly complete, you should walk away knowing:
- What was installed — the fan model, the piping path, the discharge location, and why those choices were made for your specific home
- Why it was designed that way — what the site assessment revealed and how the design responded to it
- How performance will be confirmed over time — both in terms of radon levels (through post-mitigation testing) and in terms of the mechanical system itself (a monitor that confirms the fan is continuing to move air efficiently)
That last point is worth dwelling on. Radon fans run continuously, and like any mechanical component, they can degrade or fail without obvious signs. Knowing that your fan is operating — not just that it was installed — is part of what makes long-term mitigation reliable rather than assumed. Ask about how ongoing performance is monitored, and what a re-test schedule looks like after installation. Royal Radon’s radon mitigation services treat verification as a standard part of the process, not an optional follow-up.
The Bigger Picture: Why Borderline Results Deserve Better Advice
Homeowners sitting on a just-over-200 result are often caught between two uncomfortable experiences: the contractor who creates urgency to close a sale, and the paralysis of not knowing what the number actually means. Neither of those is a good outcome.
The right approach is the one that treats you as someone capable of making a good decision when given clear information. That means honest guidance about test quality, realistic discussion of exposure and risk, genuine consideration of staged options where they make sense, and a clear explanation of what mitigation actually involves if and when you decide it’s the right move.
Radon is worth taking seriously. A borderline result is not a crisis — but it is a signal worth following up on with care.
Want a Calm Second Opinion?
If you’re sitting on a borderline result and want an honest conversation about what it means and what your options are, Royal Radon is ready to help — without pressure and without guesswork.
Book your radon assessment online, or call or text (403) 614-4094. No guessing, no pressure, no surprises once the work starts.