How to Test for Radon in Canada: A Simple Step-by-Step Guide

You can test your home for radon this weekend for about $40 and 10 minutes of setup. The hard part isn’t the test. It’s knowing which kit to grab and where to put it.

Radon is the second-leading cause of lung cancer in Canada. About 1 in 12 Ontario homes read above the action guideline, and up to 1 in 5 in higher-radon regions. You can’t see it, smell it, or feel it. A test is the only way to know.

This guide walks you through the whole thing. Pick a kit. Place it. Read the number. Act on it.

The short version:

• Testing is cheap and easy. A DIY kit runs $25 to $60. A pro test with us is $99.
• Pick one of three paths: a mail-in kit, a plug-in monitor, or a pro test.
• Put the kit in the lowest room you actually live in. Not the crawl space.
• Run it for the full time on the package. Don’t cut it short.
• Health Canada’s action level is 200 Bq/m³. Above that, plan to fix it.
• Test in winter if you can. The reading is more honest that way.

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The 5 steps to test your home

Testing for radon is a short process. Here’s the whole thing in five steps.

1. Pick your test. Mail-in kit, plug-in monitor, or pro.
2. Place it right. Lowest lived-in level, off the floor, away from drafts.
3. Run it for the full time. 2 to 7 days short-term. 91+ days long-term.
4. Get your number. Mail the kit to the lab, or read the monitor screen.
5. Act on the result. Under 200 is fine for now. Over 200, plan a fix.

The rest of this guide is just detail on each step. Let’s start with the choice most people get stuck on.

Step 1: Pick your test

You have three real options. Here’s the honest split.

	Mail-in kit	Plug-in monitor	Pro test
Cost	$25 to $60	$200 to $400	$99 to $399
Best for	First check, no rush	Ongoing tracking	Deadlines, warranty claims
How you get results	Mail to a lab	Screen or phone app	Written report from us
Time to a number	1 to 4 weeks	24 hours to 7 days	3 to 7 days
Reusable?	No, one use	Yes, forever	No

For most homeowners, a $40 mail-in kit is the right first step. It uses the same lab process a pro uses. The chemistry is identical.

Buy a long-term alpha track kit. Run it for 91 days. Mail it in. If the result is under 100 Bq/m³, you’re done for years.

Want ongoing readings? A plug-in monitor pays off over time. It shows you when winter spikes hit and whether a basement reno changed your numbers.

Need it fast, or need it for a home sale or a Tarion claim? That’s when a pro test is worth it. More on that below.

Step 2: How to use a mail-in charcoal kit

Charcoal canister kits are the most common short-term test on store shelves. Here’s how to run one right.

• Open the kit indoors, at the test spot. The charcoal starts soaking up radon the moment you open it. Don’t open it in the car.
• Set it in the lowest room you live in. A finished basement bedroom or family room. Not a crawl space you never enter.
• Put it 80 cm to 2 m off the floor. A shelf or table at eye height works.
• Keep it 50 cm from walls, vents, doors, and windows. Drafts skew the reading.
• Close your windows and outside doors. Do this for 12 hours before you start, and keep them closed during the test. This is called closed-house conditions.
• Leave it alone for 2 to 7 days. Follow the exact time on the package.
• Seal it and mail it the same day you finish. Charcoal readings drift if the kit sits around. Write down your start and stop times on the card.

The lab counts the radon decay and emails you a number. Most results come back in 1 to 2 weeks.

An alpha track kit works the same way, but you leave it in place for 91 days or more. Health Canada prefers the long-term kit for home testing. A longer test smooths out the daily and weekly swings.

Step 3: How to use a plug-in monitor

A continuous monitor reads radon hour by hour. No lab. No mailing. Popular Canadian picks are the Airthings Corentium Home, the Ecosense RadonEye RD200, and the Aranet RN+.

Here’s how to set one up.

• Place it by the same rules as a kit. Lowest lived-in room, off the floor, away from drafts and vents.
• Give it 24 hours before you trust the first number. These devices need time to settle.
• Read the 7-day average, not the hourly spike. Radon jumps around all day. One high hour isn’t your real level.
• Leave it running. The value of a monitor is the long view. Watch how your home changes across seasons.

For families with kids in a basement bedroom, a $250 monitor is often the smart buy. You test once and then you just know, year-round.

We drop off a Corentium monitor for every Breathe Radon Free test. We’re not paid by the brand. It’s the line we trust enough to leave on a customer’s floor.

Step 4: Common testing mistakes to avoid

Most bad home tests fail because of setup, not the kit. Here are the traps.

• Testing the wrong room. A crawl space or a garage tells you nothing about where you sleep. Test where you breathe most.
• Opening windows during the test. Fresh air lowers the reading and hides a real problem. Keep the house closed.
• Running a fan or dehumidifier nearby. Both pull air across the kit and throw off the count.
• Putting a charcoal kit in a damp room. Humidity ruins charcoal readings. Skip the bathroom, kitchen, and laundry room.
• Cutting the test short. A 91-day kit pulled at day 40 gives a number you can’t trust.
• Letting the kit sit before mailing. Charcoal keeps absorbing. Mail it the day you finish.
• Testing only in summer. Summer readings can run 30 to 50 percent low. Test in winter if you can.

Get these right and a $40 kit gives you a number you can act on.

Step 5: Read your result and act

Your number comes back in Bq/m³ (Becquerels per cubic metre). Canada uses this unit. Here’s what the ranges mean.

• Under 100 Bq/m³. You’re in good shape. Retest in 5 years, or after a big reno.
• 100 to 200 Bq/m³. Below the guideline, not zero risk. Consider a long-term confirmation test if kids sleep in the basement.
• 200 to 600 Bq/m³. Above Canada’s action guideline. Health Canada says fix within 2 years.
• Over 600 Bq/m³. Fix within 1 year. No need to panic. Risk builds over decades, not days.

A high reading isn’t an emergency, but it isn’t nothing. You have time to plan a fix. The whole point of testing is to find out so you can act on it.

Want the full breakdown of what each number means? Our guide to radon levels explained covers every range.

When should you retest?

One test isn’t forever. Retest your home if any of these happen.

• 5 years have passed since a low result.
• You finished the basement or added a bedroom below grade.
• You installed a sump pump or changed your HVAC.
• You did major foundation work that opened or sealed cracks.
• Your first test read high and you want a second number before spending on a fix.

Renovations change how air moves through your home. That changes your radon level. A $40 retest is cheap insurance after a big project.

DIY kit vs pro test: which should you use?

A DIY kit works for most Canadian homeowners. A pro test is the right call in specific cases. Here’s the honest line.

When DIY is plenty

You own your home. You’re curious. You have no deadline.

Buy a long-term alpha track kit for $40. Run it 91 days. Mail it in. If it reads low, you’re set for years.

DIY works because the lab does the same math for you and for us. You save money and lose nothing on accuracy.

When to book a pro

A few cases call for a certified test from the start.

• Buying a home. Your closing is weeks away. You need a pro short-term test with a signed report.
• Selling a home. Buyers trust a pro report more than a mail-in slip.
• Filing a Tarion warranty claim. Tarion needs a certified measurement to trigger builder-paid mitigation.
• Confirming a fix worked. The test after a mitigation system goes in should be done by someone independent of the installer.
• You already tested high. A second test by a different method removes doubt before you spend on a system.

We walk you through the Tarion claim process for free if you test with us.

Local context for Ontario homes

Where you live changes the odds, but not the need to test.

• Guelph, Kitchener, and Wellington County sit on dolostone bedrock. Home radon there runs about double the central GTA.
• Toronto averages low, but pre-war stone foundations in older neighbourhoods can read high.
• Newer subdivisions anywhere in Ontario can run high too. Tight, energy-efficient homes trap radon. They don’t repel it.

A radon map is a hint, not a verdict. Two houses next door can read 10 times apart. The only way to know your home is to test your home. Free kits show up every fall through Take Action on Radon’s 100 Test Kit Challenge. Worth a look before you buy.

What to do next

Testing is the easy part. Here’s your move.

• No rush? Grab a long-term kit and start this weekend.
• Want it done for you? Our $99 residential test includes a written report and Health Canada protocol.
• On a deadline or filing a claim? Book a pro test with a fast turnaround.

If a $40 kit is the right answer for you, that’s what we’ll tell you. We don’t sell tests to homeowners who don’t need them.

Book a $99 radon test in 60 seconds.

Frequently asked questions

How do I test my house for radon?

Pick a test, place it in the lowest room you live in, run it for the full time, then read the result. A mail-in kit costs $25 to $60 and ships to a lab. A plug-in monitor costs $200 to $400 and shows results on a screen. A pro test with us is $99 with a written report.

How long does a radon test take?

Short-term kits run 2 to 7 days, plus 1 to 2 weeks for the lab. Long-term kits run 91 days or more. A plug-in monitor gives a first reading in 24 hours. Our full guide to how long a radon test takes covers every timeline.

Where should I put the radon test kit?

The lowest level of your home you spend time in. A finished basement bedroom or family room is ideal. Keep it 80 cm to 2 m off the floor, 50 cm from exterior walls, vents, and windows. Not in a kitchen, bathroom, or laundry room.

Can I test for radon myself, or do I need a professional?

You can test yourself for most cases. A DIY kit uses the same lab process a pro does. Book a pro when you’re buying or selling a home, filing a Tarion claim, or confirming a mitigation system worked.

What is a high radon reading in Canada?

Health Canada’s action guideline is 200 Bq/m³. Above that, plan to fix within 2 years. Above 600 Bq/m³, fix within 1 year. Under 100 Bq/m³ is in good shape. Check the C-NRPP device list before buying any kit.

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Authored by the Breathe Radon Free Team. Every claim is backed by a primary source. Full bibliography at /sources.