Continuous Radon Monitors: When They're Worth It (Canada, 2026)
Radon isn’t one number. It moves. Your level can double from a mild fall day to a cold January night.
A one-time test gives you a single snapshot. A continuous radon monitor gives you the whole movie.
So which do you need? For most homes, a one-time test is enough. But some homes really do benefit from watching radon year-round. This post tells you which is which.
The short version:
- A continuous radon monitor (CRM) is a reusable device that reads your radon all day, every day.
- Most homeowners don’t need one. A proper one-time test answers “do I have a problem?” just fine.
- A monitor earns its keep when your level sits near the guideline, after you mitigate, or when a basement bedroom is in play.
- Good consumer monitors run $200 to $400. Pro-grade lab devices run $1,500 and up. You almost never need the pro tier at home.
- No home monitor counts for a real estate deal or a Tarion claim. Those still need a calibrated pro test.
What a continuous radon monitor actually does
A continuous radon monitor is a small box you keep in your home. It reads the air and shows you a running average.
Most give you a first number in about 24 hours. The reading gets more reliable after about a week.
That’s the whole point. Radon swings day to day and season to season. A device that watches all the time catches those swings. A single test can’t.
If you want a head-to-head on specific models, we already ranked them in our best radon detector guide. This post is about something different. It’s about whether you need ongoing monitoring at all.
One-time test vs continuous monitor: what’s the difference
Both measure radon. They answer different questions.
A one-time test is a snapshot. You run it for a few days or a few months, then read the result. It tells you where you stand right now.
A continuous monitor is a live feed. It never stops reading. It tells you how your level changes over weeks, seasons, and years.
| One-time test | Continuous monitor | |
|---|---|---|
| What you get | One average, once | A live, rolling average |
| Runs for | 2 to 7 days, or 91+ days | Years |
| Cost | $30 kit, or $99 pro test | $200 to $400 device |
| Best for | ”Do I have a problem?" | "Is my level changing?” |
| Reusable | No | Yes |
| Counts for a home sale | Pro test, yes | No |
For most people, the one-time test wins. It’s cheaper, it’s simpler, and it answers the big question. You only need the monitor when the answer is “watch this over time.”
Who actually needs a continuous monitor
Here’s the honest list. Most homes aren’t on it.
You benefit from a continuous monitor if:
- Your level sits in the grey zone. A reading between 100 and 200 Bq/m³ is below Canada’s action guideline of 200, but it isn’t zero.
A monitor lets you watch it through a full winter, when levels run highest. - You just mitigated. After a fan goes in, you want proof the system keeps working. A monitor flags the day a fan fails or a level creeps back up. More on mitigation in our mitigation cost guide.
- A child sleeps in a basement bedroom. That’s the highest-exposure spot in the house. Ongoing eyes on it can be worth the peace of mind.
- You renovate often. New flooring, a sealed sump, or an HVAC change can shift radon paths. A monitor catches the change without a fresh test each time.
- You live in a known hot spot. Some Ontario pockets test high again and again. If your neighbours read high, year-round tracking makes sense.
If none of these fit you, one good test every few years is plenty. Save your money.
What continuous monitors cost
There are two tiers, and the price gap is huge. Most people only ever need the first one.
| Tier | Price (CAD) | Who buys it |
|---|---|---|
| Consumer monitor | $200 to $400 | Homeowners tracking their own house |
| Pro-grade lab monitor | $1,500 to $2,200 | Certified testers, labs |
A consumer monitor (think Airthings Corentium or Ecosense RadonEye) is all a homeowner needs. It reads well enough to tell if you’re safe, borderline, or high.
The pro-grade tier is a different animal. It ships with a calibration certificate and gets checked every year. That’s what makes its numbers hold up in a home sale or a warranty claim.
You do not need a $1,500 device to watch your own basement. That’s like buying a delivery van to carry your groceries.
Accuracy, calibration, and drift over time
Here’s the part most buyers miss. A consumer monitor is accurate enough to act on, but not accurate enough for paperwork.
Left in one good spot for a week or more, a decent monitor gets close to your home’s true average.
But consumer monitors don’t come with a calibration certificate. And they drift a little as they age. A device that read spot-on in year one might read a bit off by year eight.
Three simple habits keep a monitor honest:
- Check that your model is on the C-NRPP consumer device list before you buy.
- Once a year, move it around the house to sanity-check the numbers.
- If it’s more than 7 to 10 years old, compare it against a fresh test.
Drift is slow and small. For tracking your own home, it doesn’t matter much. For a legal document, it matters a lot, which brings us to the next point.
DIY monitor vs hiring a pro: when each makes sense
Most Ontario homeowners can start with a monitor they buy themselves. Some can’t. Here’s the split, told straight.
When a monitor you buy is plenty
You own your home. You want to know your level and watch it over time. You have no deadline and no paperwork.
Buy a consumer monitor. Put it in the lowest level you actually use. Read the long-term average. Done.
If it stays under 100 Bq/m³, relax. If it climbs past 200, plan a fix. Our radon levels guide breaks down what each number means.
When you need a certified pro test instead
A monitor won’t cut it in these cases. You need a calibrated test from the start.
- Buying or selling a home. Buyers, agents, and lenders want a signed report, not a phone screenshot.
- Filing a Tarion claim. Tarion needs a certified measurement to trigger builder-paid mitigation.
A home gadget doesn’t count. - Proving your mitigation worked. The sign-off test should come from someone independent of the installer.
We help Ontario homeowners with all of these. A residential pro test is $99 flat. A faster real estate test is $399. Tarion claim help is free for test customers. See our full pricing and services.
Here’s the honest truth: a monitor and a pro test aren’t rivals. Lots of smart homeowners do both. They test once with a pro to get a solid baseline, then keep a monitor running to watch the trend.
Where to put your monitor (this matters more than the model)
The best monitor in the wrong spot gives you a junk number. Health Canada’s guide spells out the rules.
- Place it in the lowest level you actually live in, not the crawl space.
- Keep it 80 cm to 2 m off the floor.
- Stay 50 cm away from windows, vents, and outside walls.
- Skip the kitchen, bathroom, and laundry room. Humidity throws it off.
- Give it at least 7 days before you trust the average.
One more thing. Winter readings run higher than summer because of the stack effect. If a summer read lands near the guideline, watch it through the cold months too. A monitor makes that easy.
What to do next
Start with the question, not the gadget. Do you know your home’s radon level yet?
If you don’t, get one solid test first. A $99 pro test gives you a baseline you can trust. Then decide if your home is one of the few that benefits from year-round watching.
Radon is the top cause of lung cancer for people who’ve never smoked in Canada.
Frequently asked questions
Is a continuous radon monitor worth it?
For most homes, no. A one-time test answers “do I have a problem?” for less money. A monitor is worth it when your level is borderline, when you’ve just mitigated, or when a child sleeps in a basement bedroom and you want ongoing eyes on it.
What’s the difference between a radon monitor and a radon test kit?
A test kit runs once and gives you a single number, often through a lab. A continuous monitor is reusable and reads your radon all day, every day, for years. The kit answers a one-time question. The monitor tracks the trend.
How much does a continuous radon monitor cost in Canada?
A good consumer monitor runs $200 to $400. Pro-grade lab devices run $1,500 and up, but you don’t need that tier for your own home. The pricier consumer models mostly add Wi-Fi, apps, and extra air sensors, not better radon accuracy.
Can I use a continuous monitor for a real estate deal or a Tarion claim?
No. Consumer monitors aren’t calibrated with a certificate, so they’re not accepted for home sales, Tarion warranty claims, or post-mitigation proof. Those need a calibrated professional test.
Do continuous radon monitors need calibration?
Consumer monitors don’t get the yearly recalibration that pro devices do. They drift slowly as they age. If yours is more than 7 to 10 years old, compare it against a fresh test to make sure it’s still reading true.
Should I keep a monitor running after I fix my radon?
Yes, this is one of the best uses for one. A monitor tells you the day a fan fails or a level starts creeping back up, long before a once-a-year test would catch it.
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Authored by the Breathe Radon Free Team. Every claim is backed by a primary source. Full bibliography at /sources.
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