How to Test Your Home for Radon (Canada)

The short version

1. Buy a long-term alpha track test kit (~$30–$60) or a digital radon monitor
2. Place it in the lowest liveable area of your home, closed-window conditions
3. Leave it for at least 91 days — ideally during heating season (October through April)
4. Mail it to the lab, get results, and act on what you find

That's it. Testing is simpler than most people expect, and it's the only way to know what's in your air.

Step 1: Choose your test type

There are two main approaches to DIY radon testing:

Mail-in test kits (recommended for a first test)

Passive test kits — either charcoal (short-term) or alpha track (long-term) — are the simplest and most affordable 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 significantly day to day and season to season, so a 4-day test may not reflect your real average exposure. Use short-term kits for pre-purchase screening or when you need results quickly.
• Long-term alpha track kits (91+ days): The gold standard for Canadian homeowners making mitigation decisions. These average out daily and seasonal variation and give you a reliable picture of your actual long-term exposure. Health Canada recommends long-term testing for all mitigation decisions.

Digital radon monitors (recommended for ongoing monitoring)

Electronic monitors measure radon continuously and display real-time and long-term averages. They're reusable, more expensive upfront ($150–$500), and excellent for year-round awareness or for tracking your levels after mitigation. Some models are C-NRPP approved.

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

Step 2: Choose the right location

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

Do:

• Place it in the lowest level of your home where people spend time — finished basement, main floor if no basement, or a bedroom if that's the lowest liveable space
• Keep it at least 50 cm from the floor and away from exterior walls
• Place it in a room people use regularly — not a storage room or unfinished utility space

Don't:

• Place it in a bathroom, kitchen, or laundry room (humidity and air movement affect readings)
• Place it near a window, exterior door, or HVAC vent
• Move it during the test period

Multi-floor homes: Test the lowest liveable level first. If you find elevated levels there, consider testing upper floors too.

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

Step 3: Set up closed-building conditions

For the most accurate results — especially with long-term kits — your home should be under "closed-building conditions" during as much of the test as possible.

Closed-building conditions mean:

• Keep windows and doors closed except for normal entry and exit
• Don't run exhaust fans or ventilation systems for extended periods during the test
• Normal day-to-day living is fine

This isn't about sealing your house — just not leaving windows open for hours at a time. Normal breathing and HVAC operation are fine.

If you're using a long-term kit over 91+ days, you don't need to be perfect about this. The long averaging period naturally compensates for occasional open windows.

Step 4: Time your test for accuracy

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

A test started in spring or summer will likely underestimate your actual exposure, since radon concentrations drop when windows are open and soil/foundation conditions change with temperature.

If you need to test outside heating season — for example, a home sale in summer — a short-term test is your only realistic option. Just understand the result is a lower-bound estimate, not a true annual average.

Step 5: Mail and wait

For mail-in kits, follow the manufacturer's instructions for sealing and return shipping. Most kits include a prepaid envelope. Results are typically delivered by email within 1–3 weeks of the lab receiving the kit.

For digital monitors, simply read the long-term average on the device or app after the test period ends.

Step 6: Interpret your results

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

Health Canada's action level is 200 Bq/m³. If your result is at or above this level, contact a certified mitigation professional.

Use our free result interpreter to understand what your specific reading means for your household.

After your test

Result below 200 Bq/m³: You're below the action level. File the result for your records, plan a follow-up test in a few years, and consider a digital monitor for ongoing peace of mind.

Result above 200 Bq/m³: Find a certified mitigation professional in your province. Get 2–3 quotes. Most systems are installed in a single day and cost $1,500–$3,500.

Result between 100–200 Bq/m³: This is a grey zone. You're below the action level but not at zero risk. Consider mitigation, especially if you have young children or are a smoker. At minimum, plan a follow-up test in 2 years.

Do I need a professional test?

DIY kits are perfectly valid for most situations. You need a professional test if:

• You're in a real estate transaction and need certified results quickly (48–96 hours)
• You need a certified, documented report for legal or landlord purposes
• Your results are borderline and you want an authoritative second opinion

A certified measurement professional uses continuous electronic monitors and provides a formal report. This typically costs $150–$300. Find one near you.