How to test for radon in your home

What are the steps of a radon test, in order?

There are seven, and only the first and the last take any effort.

1. Get a long-term detector from a supplier whose price includes laboratory analysis.
2. Pick the room: the lowest level of the home that someone uses for hours each day.
3. Choose the spot inside that room, following the placement rules further down.
4. Open the detector, set it out, and record the start date and time straight away.
5. Leave it where it is for at least 91 days of heating season and live as you normally do.
6. Close or reseal it as the instructions describe, record the end date and send it to the laboratory.
7. Compare the reported average with the guideline and file the report with your house papers.

The rest of this page takes those steps one at a time. The rules on duration, season and placement come from Health Canada's measurement guide for homes, and nothing here needs tools or training.

Which detector should you use?

A passive long-term detector analysed by a laboratory is the standard choice. Health Canada recommends two types of passive device for long-term tests, alpha track detectors and electret ion chambers, and notes that electronic radon monitors are used as wellsource. The alpha track kind is the familiar mail-order kit: a small plastic capsule with no battery, no display and nothing to switch on.

Two third-party sources sell such kits to Albertans, and their prices are theirs, not ours. As of October 2026, the Evict Radon National Study offers an at-cost long-term kit for $53.99 with free shipping, and ordering one requires consent to share the result with researchers in de-identified formsource. As of October 2026, Alberta Lung sells a 90-day test through HomeRadonTest.ca for $70.00, with two-way shipping and laboratory analysis includedsource. Whatever the label on a kit says, leave it out for the 91 days Health Canada asks for. We found no free test kit program listed as open to Calgary residents in general when we checked in October 2026source.

A consumer electronic radon monitor is an option if you want to watch the number yourself. C-NRPP has tested consumer-grade electronic radon monitors and publishes the models it approves; it notes that they cannot be professionally calibrated, are not approved for use by measurement professionals, and should be left in place for at least 3 monthssource. Our page on radon test kits available in Calgary compares the options in more detail.

When should you start the test?

Start when the furnace comes on for the season. Health Canada's advice is to test for at least three months, ideally between October and Aprilsource. At least 91 days of the test should fall in the heating season, when windows are closed and indoor radon tends to be highestsource. In Calgary that window is easy to hit, because furnaces are running for the whole of it.

The recommended length is 3 to 12 months, and 91 days is the minimumsource. Longer is better, up to a full year, because a longer test averages more weather. Health Canada does not recommend any test shorter than 91 dayssource, so resist the urge to mail the detector early to see the number.

Count the days from the date you set the detector out, and mark the earliest end date on a calendar. A kit placed late in the season can still be used. It has to stay out until it has collected its share of closed-window weather, which may mean leaving it through the summer and into the next fall.

Which room should you test?

Health Canada's guide calls for a regularly occupied room, meaning one used for four hours a day or more, on the lowest lived-in level of the homesource. The rule follows people. The aim is to measure the air somebody breathes for a good part of each day, not to find the highest reading in the building.

• Basement with a bedroom, family room, home office or gym in daily use: test there.
• Basement used only for laundry, storage and the furnace: test on the main floor, in a bedroom or living room.
• Basement suite with a tenant: the suite is somebody's lowest lived-in level, so it needs its own detector.
• House on two kinds of foundation, such as a basement plus an addition over a crawl space or slab: consider one detector above each.

If you plan to finish the basement soon, test the house as it is used now and again once people start spending time downstairs. A change in how a level is occupied changes which measurement counts.

Where exactly should the detector sit?

About 30 cm or more above the floor, away from walls, and clear of kitchens, bathrooms, laundry rooms, vents, heat sources, direct sunlight and electronicssource. In practice that means a shelf, a side table or a bookcase toward the middle of the room, somewhere it can stay for months without being knocked, dusted around or tidied away.

What should you write down?

Four things on the first day and two on the last. The laboratory needs the dates to calculate an average, and you or a future buyer will need the rest to trust the number later.

Most kits come with a form or an online registration that asks for some of these. Fill it in on the day, not from memory at the end of the winter. Then take a photo of the detector in place with the form beside it, and keep a copy of everything you send.

What should you do while the test runs?

Nothing different, which is the whole point. A long-term test is meant to capture the house as it is lived in: the usual thermostat setting, the usual doors and windows, the usual time away at the holidays. Changing your habits to help or hurt the number only makes it describe a house you do not live in.

Do leave the detector exactly where it is. Tell everyone in the household what it is, including children, guests and anyone who cleans. If it does get moved, put it back, and add the date and the circumstances to your notes. If it is lost, damaged or soaked, the fair choice is to start again with a new one.

Do not run a quick second test alongside it and stop early because that one looked fine. Short-term tests typically run for 2 to 7 dayssource, and a reading over so short a time can sit well above or below the seasonal average.

How do you end the test and send it in?

Follow the instructions in the kit to the letter, because each maker closes its detector differently. Some go back into a sealed bag and some are closed with a cap or a sticker.

Write down the end date and time before you do anything else. Complete the form, package the detector as directed and send it without delay, since the laboratory's calculation assumes the test ended on the date you wrote.

Then wait for the report. It should state the average radon concentration in Bq/m³ and the dates the laboratory used. Check that those dates match your notes.

What do you do with the result?

Compare it with one number. The Canadian guideline is 200 Bq/m³, and Health Canada recommends corrective action when the annual average is above itsource. Above the guideline, the recommendation is to mitigate within one year, sooner for higher levels, and to bring radon as low as reasonably achievablesource.

Under the guideline, Health Canada's recommendation to act does not apply and the next step is your decision; no radon level is free of risk and a lower one is always better. With a result just under the line, a second long-term test in another heating season is a choice open to you. A result over the line does not need a second test before you act.

If your report is in pCi/L, the unit converter for Bq/m³ and pCi/L changes it into Canadian units, and our explanation of the Canadian radon guideline shows how fast to act in each range. Above the guideline, the next page to read is radon mitigation for Calgary homes.

Keep the report. Health Canada recommends testing again after a mitigation system is installed, every 5 years while one is in service, and after any renovation that affects the structure or ventilation of the homesource.

When is it worth having a professional run the test?

When the result has to stand up to someone else, or when you would simply prefer not to manage it. A sale or purchase, a rental unit, a daycare or a disagreement between an owner and a builder are all cases where a documented test by a certified person carries more weight than a homeowner's notes. Health Canada recommends hiring professionals certified by the Canadian National Radon Proficiency Program (C-NRPP)source.

Our long-term radon testing service follows the same method described here, with placement, records and the report handled for you. Either way, the recommendation from Health Canada is the same: every home should be tested, wherever it is and whatever type of building it issource. A neighbour's result cannot stand in for yours, because levels differ even between similar houses side by sidesource. If you are still deciding whether testing is worth the trouble, what the research found in Calgary houses is the place to start.