You can't see radon, smell it, or feel it. So the only way to know if your home has a problem is to measure it. The good news: testing is cheap, easy, and something you can do yourself. Here's how to do it right, and when it's worth paying a pro instead.
Why test at all?
Radon is the number one cause of lung cancer in Canadians who don't smoke. It builds up indoors and you'd never know from how the air feels. A test is the one and only way to find out your home's level. No guessing, and no assuming you're fine because the house is new or the basement is finished. New homes and finished basements test high all the time.
It's also the cheapest step in the whole process. A test kit costs about the price of a takeout dinner, while the thing it's screening for is a leading cause of lung cancer. There's no good reason to skip it.
Short-term vs long-term tests
There are two kinds of radon test, and the difference matters.
Long-term tests (what Health Canada recommends)
A long-term test sits in your home for at least three months, and ideally longer. Radon swings day to day and season to season, so a long test gives you a true average of what you actually breathe. Health Canada recommends a test of at least three months. This is the gold standard for deciding whether to mitigate.
Short-term tests
A short-term test runs a few days to a week. It's faster and useful when you need a quick answer, like during a real estate deal or to confirm a mitigation system worked. The trade-off is that it's a snapshot, not an average, so it can read high or low depending on the week. Use it for speed, then confirm with a longer test when you can.
DIY test kit vs hiring a pro
For most homeowners, a do-it-yourself kit is all you need. Here's how to choose.
DIY kits
A home radon test kit costs roughly $30 to $60. Look for one that's C-NRPP approved, which is the Canadian program that certifies radon devices and professionals. You place the detector, leave it for the test period, then mail it to a lab that emails your result. Simple, cheap, and reliable if you follow the instructions.
Hiring a C-NRPP measurement pro
You'd hire a certified measurement professional when the stakes are higher: a home purchase or sale, a workplace, or when you want a documented third-party result. They use calibrated equipment and handle placement and reporting. It costs more than a kit, but the result carries more weight.
C-NRPP is the Canadian National Radon Proficiency Program. It's the certification Health Canada points to for both radon devices and the people who measure and fix radon. Look for it on kits and on any pro you hire.
What about digital radon monitors?
You'll also see plug-in digital radon monitors for sale, usually $150 to $300. They give you a live reading and track trends on a screen or app, which is handy if you like data or want to watch how a fix is working over time. The catch: consumer monitors aren't always as accurate as a lab-analyzed kit, and they generally aren't accepted as an official result for a real estate deal. Use one for ongoing peace of mind, but base your mitigation decision on a proper long-term test.
How long testing takes, and when to test
Plan for a long-term test of at least three months. That feels like a long wait, but it's the only way to get a real average, and it's passive, so you just leave the detector alone and forget about it.
The best time to test is during the heating season, roughly October through April. In a Canadian winter your home is sealed up tight and the furnace is running, which is exactly when radon builds up most. A winter test shows your home closer to its worst case, which is what you want to plan around.
Where to put the detector
Place the detector in the lowest level you use regularly, like a finished basement, or the main floor if you don't have a basement. Follow these basics:
- Put it in a lived-in room, not a crawl space, closet, or furnace room.
- Keep it about waist to head height, away from drafts, windows, exterior doors, and heat sources.
- Leave it undisturbed for the whole test period.
- Don't test in the kitchen or bathroom, since humidity and airflow throw off the reading.
Reading your result
When your result comes back, it's a single number in Bq/m³. Compare it to Health Canada's 200 Bq/m³ guideline: at or above, plan to mitigate; below, you're in better shape, though never truly at zero. If you want the full breakdown of what each range means and when to act, we cover it in the safe radon levels guide. And don't over-read a single short-term test — one high week isn't a verdict. A long-term test is what settles it.
What happens after a high result
If your test comes back at or above Health Canada's 200 Bq/m³ guideline, don't panic. This is a fixable problem. The next step is mitigation: a certified crew installs a system that pulls radon from under your foundation and vents it outside, then re-tests to prove your level dropped. To understand the numbers first, read our guide to safe radon levels. For the price, see the radon mitigation cost guide.
Your odds also depend on where you live, since some areas run higher, which you can see in Canada's radon hotspots and on local maps like the Calgary radon map or the Winnipeg radon map. When you're ready to test or fix, pick your city below for a C-NRPP certified local team.