Radon Testing in Canada: Everything You Need to Know Before You Test
About 1 in 5 Ontario homes test above Canada’s radon action guideline of 200 Bq/m³. Most owners have never run a single test. That gap is the whole reason this guide exists.
Radon is invisible. It has no smell. You can’t feel it.
A test is the only way to know if your home is one of the high ones. The test itself is cheap, simple, and quick once you know which one to pick.
This guide walks you through every type of radon test sold in Canada, where to place the kit, how to read the result, and when to skip DIY and book a pro.
The short version:
- About 1 in 5 Ontario homes read above the 200 Bq/m³ Health Canada guideline
- A long-term (91+ day) test is the most reliable single number for your home
- A short-term test (2 to 7 days) is fine for a first screen or a real estate deadline
- Tests should sit in the lowest room you actually live in, not the crawl space
- DIY kits cost $25 to $50, a pro residential test is $99, a real estate test is $399
- Test in winter if you can. Stack effect makes the reading more conservative.
Why test for radon at all?
Radon is the second-leading cause of lung cancer in Canada. The Canadian Cancer Society puts it as the top cause for people who don’t smoke.
You won’t feel sick from it. There are no headaches, no cough, no shortness of breath. The damage happens over years of low-dose exposure to the lungs.
The good news: a high reading isn’t an emergency. You have time to fix it. The whole point of testing is to find out so you can act.
If you’ve owned your home for more than 5 years and never tested, that’s the gap to close this season. If you bought a newer build, the Tarion warranty path might cover any fix needed.
What’s the difference between a radon test and radon testing?
People search both phrases. The meaning is the same.
- A radon test is a single measurement event. One device, one stretch of time, one result.
- Radon testing is the practice. The full process from kit choice to placement to lab result to action.
We’ll use both in this guide. The takeaways are the same either way.
The four types of radon tests sold in Canada
There are four common ways to measure radon at home. Each uses different physics and runs on a different clock.
1. Charcoal canister (short-term)
A small puck of charcoal in a sealed cup. You open it, leave it in your basement for 2 to 7 days, then ship it to a lab.
Charcoal soaks up radon. The lab counts the decay and emails you a number.
Charcoal kits are cheap and fast. They’re also the most affected by humidity, drafts, and weather swings. A wet week can throw the reading off.
2. Alpha track detector (long-term)
A small plastic chamber with a sensitive film inside. Radon decay leaves tiny marks on the film. You leave it in place for 91 days or more, then mail it in.
Alpha track is the kit Health Canada prefers for residential testing.
3. Electret ion chamber
A charged disc that loses voltage as radon decays around it. The lab reads the voltage drop and works backward to the radon level.
Electret kits can run short or long. They’re accurate but pricier than charcoal or alpha track. You’ll see them more often in pro testing than on store shelves.
4. Continuous radon monitor
A plug-in or battery device that reads radon hour by hour. No mailing. No lab.
The screen (or phone app) shows the average, the peak, and the trend. Popular Canadian picks are the Airthings Corentium Home, the Ecosense RadonEye RD200, and the Aranet RN+. Prices run $200 to $400 for consumer models.
For what it’s worth, the Corentium Home 2 (the newer cloud-synced model) is the device we drop off for every Breathe Radon Free test. The original Corentium Home is also part of our kit. We’re not paid by Airthings; it’s the line we trust enough to leave on a customer’s basement floor.
Short-term vs long-term: which one to use
This is the choice that trips people up most. Here’s the honest split.
| Short-term test | Long-term test | |
|---|---|---|
| Duration | 2 to 7 days | 91+ days |
| Best for | Real estate deadlines, fast screen | Reliable single number for your home |
| Accuracy | Noisier, can swing 50% | Within about 25% of true average |
| Affected by weather | A lot | Very little |
| Cost (DIY) | $25 to $50 | $35 to $60 |
| Cost (pro) | $99 to $399 | $299 |
| Time to result | 1 to 2 weeks after mail-in | 4 to 6 months including mail-in |
A short-term test is a screen. It tells you if your home is probably fine or probably high. A long-term test tells you the actual yearly average.
If your short-term reads under 100 Bq/m³, you can usually stop there. If it lands in the 100 to 200 Bq/m³ range, run a long-term to confirm. If it’s over 200, you have enough info to act.
Where to place the kit
Most failed home tests fail because of where the kit went, not because the kit was bad. Health Canada has a free guide that spells out the rules.
The short version:
- Test the lowest level you spend time in. A finished basement bedroom counts. A crawl space you never enter does not.
- Place the kit 80 cm to 2 m off the floor. Eye height is fine.
- Keep it 50 cm away from exterior walls, vents, doors, and windows.
- Don’t put it in a kitchen, bathroom, or laundry room. Humidity skews the result.
- Don’t put it next to a fan, heater, or dehumidifier.
- Run the kit for the full duration on the package. Don’t cut a 91-day test short.
For short-term tests, keep windows and exterior doors closed (except for normal entry) for 12 hours before and during the test. This is called closed-house conditions.
A kit in the wrong room tells you about the wrong room. The whole point is to measure where you breathe most. For most families, that’s the lowest bedroom or family room, not the unfinished part of the basement.
What the numbers mean
Your result comes back in Bq/m³ (Becquerels per cubic metre). Canada uses Bq/m³.
The U.S. uses pCi/L. 1 pCi/L is about 37 Bq/m³.
Here’s what the ranges mean for a Canadian home.
Under 100 Bq/m³ You’re in good shape. Re-test in 5 years, or sooner if you finish your basement, swap your HVAC, or add a sump pump.
100 to 200 Bq/m³ Below Canada’s action guideline. Not zero risk. If kids sleep in the basement or someone smokes in the home, consider a long-term confirmation test or low-cost mitigation.
200 to 600 Bq/m³
Above the guideline. Health Canada says fix within 2 years.
Over 600 Bq/m³ Fix within 1 year. Don’t panic. Lung cancer risk builds over decades. But don’t sit on it either.
A few notes on the guideline:
- Canada’s 200 Bq/m³ is higher than the U.S. EPA’s 148 Bq/m³ action level. Different countries, different policies. The biology is the same.
- “Safe” isn’t really the right word. There’s no zero. Lower is always better.
- A single reading is a snapshot. Two tests done a year apart can land differently because of seasonal swings.
What it costs in Canada
Total cost depends on the kit type and whether lab analysis is included.
| Test type | Buy price | Lab fee | Total | Time to result |
|---|---|---|---|---|
| Charcoal canister | $25 to $40 | Usually included | $25 to $40 | 1 to 2 weeks after mail-in |
| Alpha track (long-term) | $35 to $60 | Usually included | $35 to $60 | 2 to 4 weeks after mail-in |
| Electret | $50 to $90 | Sometimes extra | $50 to $130 | 1 to 3 weeks |
| Continuous monitor (own) | $200 to $400 | None | $200 to $400 | First reading in 24 hrs |
| Pro residential test | $99 (us) | Included | $99 | 3 to 7 days, written report |
| Pro real estate test | $399 (us) | Included | $399 | 48 to 72 hrs, written report |
| Pro long-term test | $299 (us) | Included | $299 | 91 days plus 1 to 2 weeks |
Free kit programs run every fall through Take Action on Radon’s 100 Test Kit Challenge.
For a deeper price breakdown across kit brands and continuous monitors, we built a full radon test kit buyer’s guide.
Real estate transactions vs ongoing residential
These are two different test scenarios with two different answers.
Buying or selling a home
You have weeks, not months. A 91-day test won’t finish in time. You need a pro short-term test with a written report.
- As a buyer: Make the test a condition of the offer. Most deals get 5 to 10 business days for the inspection period. A 3 to 7 day test fits.
- As a seller: A documented test result, especially one tied to a working mitigation system, is a positive disclosure. It removes radon as a deal-killer for the next buyer.
For closing-driven timelines, our real estate radon test is $399 with a 48 to 72 hour turnaround.
Ongoing residential
You own your home. You’re not selling. You want to know if you have a problem.
This is where a long-term alpha track or a continuous monitor wins. You get a number that reflects how you actually live in the place. No rush. No weather skew.
Most families test once every 5 years if the first result was low, and re-test sooner if they renovate the basement or add a sump pump.
DIY kit vs pro test: when each makes sense
A $40 DIY kit works for most Canadian homeowners. A pro test is the right call in specific scenarios. Here’s the honest split.
When DIY is plenty
You’re a homeowner. You’re curious. You have no deadline.
Buy a long-term alpha track kit for $40. Drop it in your basement for 91 days. Mail it in. If the result is under 100 Bq/m³, you’re done for the next 5 years.
DIY works because the lab process is the same one a pro uses. The difference is the device tier and the report format, not the chemistry.
When you should book a pro instead
A few situations call for a certified test from the start.
- Buying a home. Your closing date is 2 weeks away. A pro short-term test with a signed report is what you need.
- Selling a home. Buyers and home inspectors take pro reports more seriously than mail-in lab slips.
- Filing a Tarion warranty claim. Tarion needs a certified measurement. A DIY kit won’t trigger builder-paid mitigation.
- Confirming mitigation worked. The verification test after a system installs should be done by someone independent of the installer.
- You already tested high once. A second test by a different method removes any doubt before you spend $3,000 on mitigation.
We walk Ontario homeowners through the Tarion claim process for free if you’ve tested with us.
The middle path: a continuous monitor
A $250 Airthings or RadonEye pays off if you want ongoing readings. The display tells you when winter spikes hit. It tells you if a new sump pump changed your numbers. It tells you if your mitigation fan is still doing its job.
Once you own one, you never buy another kit. For families with kids in basement bedrooms, this is often the right call.
Season matters: when to test
Radon levels swing with the seasons. Winter readings run higher than summer because of the stack effect.
Here’s what’s happening. Warm air rises through the upper floors. That pulls cool air (and soil gas) up through the basement to replace it.
Closed windows in winter trap that gas inside. Furnace cycles speed it up.
A summer test can underestimate your real exposure by 30 to 50 percent. A winter test gives the more conservative (and more useful) number.
If you’re testing in Ontario:
- Best months: October through March
- Worst months for accuracy: June through August
- For real estate deadlines: Test whenever the deal is happening. The shorter window matters more than season.
How to actually buy a kit
Stock varies by store and time of year. November (Radon Action Month) is when shelves get refreshed.
- Canadian Tire: Charcoal short-term and alpha track long-term. $30 to $60.
- Home Depot Canada: Mostly alpha track long-term. $35 to $70.
- Amazon.ca: All four kit types plus continuous monitors. $25 to $400+.
- Direct from labs (Radonova, AccuStar): Lab-direct alpha track and electret. $40 to $80.
- Take Action on Radon programs: Free in some Ontario cities during fall campaigns.
Check the C-NRPP devices list before you buy.
Local context for Ontario homeowners
Geology and home age both matter. Both vary a lot across Ontario.
- Guelph, Kitchener, and Wellington County sit on dolostone bedrock with glacial deposits above. Average home radon is roughly double the central GTA.
- Toronto averages low city-wide, but pre-war stone foundations in Cabbagetown, Riverdale, and parts of midtown can run high.
- Ottawa Valley has the highest big-city averages in Canada thanks to Champlain Sea sediments and granite bedrock.
- Newer subdivisions anywhere in Ontario can run high too. Tighter homes trap radon, they don’t repel it.
A radon map is a hint, not a verdict. Houses next door can read 10 times apart. The only way to know is to test your own. We covered the full picture in our Ontario radon guide.
Where Breathe Radon Free fits
We’re an Ontario-based testing service. Owner-led, based in Guelph, serving the Greater Toronto Area plus surrounding Southern Ontario.
If a $40 DIY kit is the right answer for your situation, that’s what we’ll tell you. We don’t sell tests to homeowners who don’t need them.
If you do need a pro test, here’s what we charge:
- Residential test: $99 flat. 3 to 7 days, written report, Health Canada protocol.
- Real estate transaction test: $399. Faster turnaround for closing timelines.
- Long-term test: $299. 91-day alpha track for ongoing residential.
- Tarion claim help: free for test customers.
Book a $99 radon test in 60 seconds.
Frequently asked questions
Are home radon tests accurate?
Yes, when used correctly. A long-term alpha track kit gives a result within about 25 percent of your home’s true average. Short-term charcoal kits are noisier (can swing 50 percent on weather) but still useful as a first screen.
How long does a radon test take?
Short-term kits run 2 to 7 days, then mail-in adds 1 to 2 weeks for lab results. Long-term kits run 91 days minimum, plus mail-in time. Continuous monitors give a first reading in 24 hours and a stable average after 7 days.
When should I test for radon?
Winter is best if you have flexibility. October through March in Ontario. The stack effect (warm air rising, pulling soil gas in) makes winter readings the more conservative number. For real estate deadlines, test whenever the deal is happening.
Where should I put the radon test kit?
The lowest level of the home you spend time in. A finished basement bedroom or family room is ideal. Keep the kit 80 cm to 2 m off the floor, 50 cm away from exterior walls, vents, and windows. Not in a kitchen, bathroom, or laundry room.
What’s a high radon reading?
Health Canada’s action guideline is 200 Bq/m³. Above that, plan to fix within 2 years.
Under 100 Bq/m³ is in good shape. Between 100 and 200, consider a confirmation test or low-cost mitigation if kids sleep in the basement or someone smokes in the home.
Can I trust a Canadian Tire or Home Depot test kit?
Yes, if it’s listed on the C-NRPP devices list and you place it correctly. Stock varies by store and season. Check the package for “Health Canada approved” or “C-NRPP listed” before you buy.
Get a $99 radon test booked in 60 seconds →
Authored by the Breathe Radon Free Team. Every claim is backed by a primary source. Full bibliography at /sources.
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