How to Test Your Home for Radon (Canada)

Testing for radon is easier than most people expect. Here's what you need to do:

1. Buy a long-term alpha track test kit (~$30–$60) or a digital radon monitor
2. Place it in the lowest livable area of your home with windows mostly closed
3. Leave it for at least 91 days, ideally during heating season (October through April)
4. Mail it to the lab, get your result, and go from there

That's it. The only way to know what's in your air is to measure it.

Step 1: Choose your test type

Mail-in test kits

Passive kits, either charcoal (short-term) or alpha track (long-term), are the simplest and cheapest option. You place the kit, leave it, and mail it to the lab when done.

• Short-term charcoal kits (48–96 hours): Fast results, but only a snapshot. Radon levels fluctuate from day to day and season to season, so a 4-day test can miss a lot. Use short-term kits when you need results quickly, like for a real estate transaction. Don't make a mitigation decision based on one.
• Long-term alpha track kits (91+ days): The gold standard. These average out daily and seasonal variation and give you a reliable picture of your actual long-term exposure. Health Canada recommends them for mitigation decisions.

Digital radon monitors

Electronic monitors measure radon continuously and show real-time and long-term averages on screen or in an app. They're reusable, cost more upfront ($160–$350), and are great for ongoing monitoring or tracking your levels after a mitigation system is installed.

See our DIY Radon Guide for a full comparison of kits and monitors available in Canada.

Step 2: Pick the right location

Where you place your test matters as much as how long you run it.

Do this:

• Place it in the lowest level where people spend regular time, such as a finished basement, main floor if there's no basement, or ground-level bedroom
• Keep it at least 50 cm from the floor and away from exterior walls
• Choose a room people actually use, not a storage room or mechanical room

Avoid:

• Bathrooms, kitchens, and laundry rooms (humidity and airflow mess with readings)
• Spots near windows, exterior doors, or HVAC vents
• Moving the device during the test

Multi-floor homes: Test the lowest livable level first. If it comes back elevated, test upper floors too.

Crawlspace homes: Test the main floor above the crawlspace, not inside the crawlspace. The question is what you're breathing.

Step 3: Closed-building conditions

For the most accurate results, keep your home under "closed-building conditions" during the test. That means:

• Windows and doors closed except for normal entry and exit
• Don't run exhaust fans or ventilation systems for extended stretches
• Normal day-to-day living is completely fine

This doesn't mean sealing your house. Just don't leave windows open for hours at a time. With a long-term kit running for 90+ days, occasional open windows won't throw off your result.

Step 4: Timing matters

Radon levels are highest in winter when your home is sealed up. The ideal window is October through April.

If you test in summer, you'll probably get a reading that's lower than your real annual average. For a home sale in July, a short-term test is your only realistic option. Just know the result is a lower-bound estimate, not a true annual picture.

Step 5: Send it in

For mail-in kits, seal and return the device using the prepaid envelope included. Most labs deliver results by email within 1–3 weeks. For digital monitors, read the long-term average on the device or app once the test period ends.

Step 6: Read your result

Canadian results come in Bq/m³ (becquerels per cubic metre).

Health Canada's action level is 200 Bq/m³. Use our free result interpreter to understand what your specific number means.

What to do after

Under 200 Bq/m³: File the result, plan a follow-up test in a few years, and consider a digital monitor for ongoing awareness.

Above 200 Bq/m³: Find a certified mitigation professional in your province. Get two or three quotes. Most systems are installed in a day and cost $1,500–$3,500.

Between 100–200 Bq/m³: You're below the action level but not at zero risk. Consider mitigation if you have young children or are a smoker. At minimum, retest in 2 years.

Do I need a professional test?

DIY kits work well for most situations. Hire a professional if:

• You're in a real estate transaction and need certified results in 48–96 hours
• You need a certified report for landlord or legal purposes
• Your result is borderline and you want an authoritative second opinion

Professional testing uses continuous electronic monitors and typically costs $150–$300. Find a certified professional near you.