Radon Testing in Canada: How to Test, Place a Detector & Read Results

Quick answer: test the home, trust the long-term average

You cannot see, smell or guess radon. The only way to know the level in your home is to test.

For a Canadian homeowner in 2026, the clean workflow is:

1. use a suitable long-term passive detector or Electronic Radon Monitor (ERM);
2. put it in a normal occupancy area on the lowest lived-in level;
3. leave it for at least 91 days;
4. make sure a below-guideline result includes at least 91 days during your home’s heating season;
5. compare the long-term average with Canada’s 200 Bq/m³ radon guideline;
6. if the long-term result is at or above the guideline, plan corrective action within one year, sooner as the concentration rises.

Health Canada’s current Guide for Radon Measurements in Homes, published May 22, 2026, is the main measurement standard used throughout this guide.

Radon Test Planner

Use this before you open a passive kit or reset an electronic monitor. It identifies the baseline level and room category, placement rules and earliest 91-day completion date without pretending Canada has one fixed winter calendar.

What radon level matters in Canada?

The Canadian radon guideline is 200 becquerels per cubic metre (Bq/m³) in a normal occupancy area.

That is a long-term household decision point, not an instantaneous alarm threshold.

Health Canada currently recommends that:

• corrective action be taken when the average annual radon level exceeds 200 Bq/m³ in a normal occupancy area;
• action be taken within one year when a home is above the guideline;
• action be taken sooner as the concentration gets higher;
• radon be reduced as much as practicable when corrective work is done.

A result of 190 Bq/m³ is not “zero risk,” and a result of 210 Bq/m³ does not mean the house suddenly became dangerous at midnight. The guideline is the Canadian action benchmark for a chronic exposure that exists on a continuum.

How common is high radon in Canadian homes?

The 2024 Cross-Canada Survey of Radon Exposure in Residential Buildings found that 17.8%, roughly 1 in 5, of single-detached, semi-detached and row-type residential buildings in its national model were at or above 200 Bq/m³.

That is much higher than the 6.9% figure from the older 2012 national survey, but it still does not mean a map can tell you whether your house is high.

The same 2024 work explicitly warns against using regional results to determine personal radon risk or decide whether one particular household needs testing. Radon varies with the building, soil, foundation, pressure differences, ventilation and how the home is used.

Your neighbour’s result is not your result.

Long-term radon test kit vs electronic radon monitor

Both can answer the core homeowner question when they are appropriate for long-term measurement and used correctly.

For passive testing, use a reputable Canadian supplier/laboratory and follow its deployment and return instructions. C-NRPP maintains a professional device and laboratory listing that includes approved alpha-track pathways.

For electronic monitors, C-NRPP publishes an independent consumer-grade ERM performance comparison. Its current table lists Airthings Corentium Home, Airthings View, Aranet RN+, Ecosense EcoQube, Ecosense RadonEye RD200 and SunRadon Luft as approved in that consumer performance program.

That wording matters. These are consumer devices that passed C-NRPP performance testing. They are not “Health Canada-certified,” and C-NRPP explicitly says the consumer units on that table cannot be professionally calibrated and are not approved for use by C-NRPP measurement professionals for client measurements.

What about Airthings Corentium Home 2?

Do not assume a newer model inherits the original model’s C-NRPP status. As verified in September 2026, Corentium Home 2 is not separately named on C-NRPP’s current published consumer performance table. If that changes, use the current C-NRPP listing rather than old product-roundup copy.

The dedicated commercial comparison belongs on its own future detector page; this guide stays focused on getting a defensible household measurement.

Where should a radon detector go?

Health Canada says to test a normal occupancy area on the lowest lived-in level.

A normal occupancy area is generally a space where someone spends about four or more hours per day on average. Bedrooms get priority when there is a choice because people spend long, continuous periods there.

Examples:

• finished basement bedroom, office, playroom or family room used regularly → test the basement living area;
• unfinished basement used for storage, laundry and mechanical equipment → test an occupied room on the main floor;
• slab-on-grade home → test an occupied ground-floor room;
• crawlspace home → test the occupied floor above it, not inside the crawlspace;
• apartment or condo → test your own normally occupied unit; do not assume an upper-floor unit cannot have radon.

Lowest lived-in level does not mean lowest physical hole in the building. A sump basin, crawlspace or unused dirt cellar may have high soil-gas concentrations, but the household guideline is built around representative air in normal occupancy areas.

Exact placement: the current Health Canada numbers

Health Canada’s May 2026 technical appendix gives useful, defensible placement distances:

• at least 30 cm above the floor;
• at least 30 cm from walls and the ceiling;
• at least 1 m from windows, exterior doors and heating/ventilation openings;
• about 10 cm of clear space around the detector, other than the surface supporting it;
• within the detector manufacturer’s operating limits.

Avoid locations that are not representative of normal breathing air or that can interfere with the measurement:

• kitchens;
• bathrooms;
• laundry rooms;
• closets or storage rooms;
• unfinished basements and furnace rooms;
• crawlspaces;
• beside an open sump, obvious foundation crack or other localized entry point;
• windowsills;
• direct sun or strong heat sources;
• directly beside TVs, routers, speakers, computers or other electronics where the device instructions or Health Canada placement guidance warn against interference.

A shelf or table in a regularly occupied bedroom, office or family room is usually much more useful than hiding the monitor beside the foundation because “radon comes from the ground.”

How long should you test for radon?

Health Canada’s current definition is at least 91 days for a long-term residential radon measurement.

Older Canadian pages often say “three months.” C-NRPP’s consumer page still uses that homeowner-friendly phrase. For ReadyHome, the precise version is better:

Run the household test for at least 91 days.

Longer can be useful. A test spanning much of a year integrates more seasonal variation. But the key mistake is stopping an electronic monitor because it produced a number after an hour, day or week.

My first week is low. Can I stop?

No. A low first week is still a short-term sample.

My monitor hit 700 Bq/m³ overnight. Do I evacuate?

A single overnight spike is not the long-term annual result used by the Canadian guideline. Keep the test running correctly. If you already have a valid long-term result at or above 200 Bq/m³, move to mitigation planning instead of chasing daily fluctuations.

The 2026 heating-season rule is stronger than “test in winter if you can”

This is the most important recent change to Canadian homeowner testing guidance.

Health Canada’s 2026 guide says at least 91 days of the measurement should occur during the heating season. It defines heating season functionally as the period when the home’s heating appliances are in use and notes that its duration varies by region and climate.

That means ReadyHome deliberately does not hard-code “October 1 to April 30” as a national rule.

The decision logic is:

• long-term result at or above 200 Bq/m³: act on it; a re-test is not required merely because the test had fewer than 91 heating-season days;
• long-term result below 200 Bq/m³ + at least 91 heating-season days: the seasonal coverage supports the below-guideline result;
• long-term result below 200 Bq/m³ + fewer than 91 heating-season days: Health Canada recommends another test so at least 91 days occur during heating season.

During a long-term test, live normally. Use heating and ventilation normally, enter and leave normally, and use windows as you normally would for the season. Do not deliberately seal the house for months or throw windows open just to manipulate the number.

Radon Result Interpreter

Enter the long-term average, not the highest hourly reading you saw in the app.

What does a result below 200 Bq/m³ mean?

If the test:

• ran at least 91 days;
• was properly located in a normal occupancy area on the lowest lived-in level; and
• included at least 91 heating-season days,

then a result below 200 Bq/m³ is below the Canadian action guideline for that measurement.

That does not mean “radon free.” Health Canada explicitly says there is no radon exposure level considered completely risk-free. It means the result does not cross Canada’s household corrective-action guideline.

Retest when major changes can alter the building or exposure pattern, including substantial foundation work, basement conversion, major ventilation/HVAC changes or other renovations that can change air movement or the lowest normally occupied level.

What does a result at or above 200 Bq/m³ mean?

For a properly placed long-term test, it means the home is at or above the Canadian guideline and corrective action should be planned.

Current Health Canada homeowner guidance says to lower the level within one year, and to act sooner as concentrations rise. It no longer makes sense for ReadyHome’s residential interpreter to preserve the older 200–600 “within two years” and above-600 “within one year” bands found in legacy material.

Health Canada recommends hiring a C-NRPP-certified radon mitigation professional. Its current radon reduction guidance says the most common approach is sub-slab depressurization and that mitigation reduces radon by more than 80% in most homes.

This page stops there. It does not turn a high result into a DIY fan-sizing, pipe-routing or foundation-drilling tutorial.

Do you need more than one radon detector?

For standard residential measurement, Health Canada’s 2026 guide says only one detector is required.

That is much better than inventing “one detector per floor.” The baseline job is to measure the lowest normally occupied level correctly.

Complex homes can still create judgment calls. An addition on a separate slab, multiple separately occupied areas or mixed foundation sections may justify professional measurement advice. That is a reason to ask a C-NRPP professional, not a reason for ReadyHome to manufacture a universal multi-detector formula.

If you own one reusable ERM and want to compare other rooms after completing the baseline test, you can move it later and follow the manufacturer’s reset/history instructions. Do not sacrifice the initial 91-day baseline by moving it around every week.

Radon in basements and crawlspaces

A finished basement counts when it is a real living space. An unfinished mechanical or storage basement usually does not.

Likewise, a crawlspace can be an important radon entry pathway without being the correct place to measure household exposure. Test the normally occupied level above it.

If an unfinished basement is about to become a bedroom, office or family room, the exposure context is changing. Testing before the renovation can identify a problem early, and retesting after substantial work can confirm the changed home.

Do condos and apartments need radon testing?

Yes. Health Canada’s 2026 home guide explicitly covers individual units in multi-unit residential buildings as well as low-rise houses.

Ground-contact units are an obvious testing priority, but upper-floor occupants should not assume their unit is radon-free. A test in your unit answers your unit’s question. It does not certify the whole building.

Do new homes need radon testing?

Yes.

Radon-control rough-ins and modern building-code provisions are useful because they can make later mitigation easier. They do not measure the finished occupied home.

A new home can still test above 200 Bq/m³, and the only way to know the occupied concentration is to test after construction.

Do not use house age, energy efficiency, a radon rough-in or a builder’s generic statement as a substitute for the measurement.

Can a radon map tell me whether my house is safe?

No.

Regional maps and the 2024 national survey are useful for showing that elevated radon exists across Canada and that some regions have higher prevalence. They are not house-level diagnostic tools.

The Cross-Canada survey specifically warns that its results should not be used to determine personal radon risk or decide whether one household needs testing.

Use a map to understand the issue. Use a detector to understand the house.

Common mistakes that ruin the decision

Putting the detector beside the sump

That measures a localized radon entry area, not necessarily representative breathing air. Place the detector in the occupied room instead. If your sump cover is sealed for radon control, preserve the seal when working around sump pumps and alarms.

Watching the hourly number like a stock ticker

Electronic monitors are useful precisely because they show variation, but that feature can make people obsess over noise. C-NRPP warns that short-term readings can be misleading in either direction.

Stopping after a low first week

A short low result can provide false reassurance. Finish the long-term test.

Calling a general indoor-air monitor a radon detector

PM2.5, CO2, VOC, humidity and temperature sensors measure different things. Unless the device has a dedicated radon measurement function, it is not a radon monitor. See the separate indoor air-quality monitor guide for smoke/PM2.5 use.

Assuming a CO alarm detects radon

It does not. Carbon monoxide alarms and radon detectors use different sensors for different hazards. See carbon monoxide detectors in Canada.

C-NRPP: what the label actually means

C-NRPP runs Canada’s radon proficiency program and separately publishes consumer electronic-monitor performance testing.

For shoppers, the useful distinction is:

• consumer ERM performance table: independently compared consumer electronic monitors for homeowner use;
• professional listed devices: instruments/laboratories approved for C-NRPP professional measurement workflows;
• certified professionals: people who have the applicable C-NRPP measurement or mitigation credentials.

Do not collapse those into “Health Canada certified.”

C-NRPP also notes that consumer ERMs on its comparison page cannot be professionally calibrated and are not approved for C-NRPP professionals’ client measurements.

Health Canada’s 2026 guide says users should consider replacing consumer ERMs five years after purchase unless they can be recalibrated to manufacturer specifications. “Consider replacing” is the accurate wording; ReadyHome does not turn that into a fake statutory expiry date.

Methodology and sources

Primary references:

• Health Canada — Guide for Radon Measurements in Homes (May 22, 2026)
• Health Canada — Canadian radon guideline
• Health Canada — Reducing radon levels in your home
• C-NRPP — Consumer-Grade Electronic Radon Monitors
• C-NRPP — Listed professional devices
• 2024 Cross-Canada Radon Survey

The article is measurement and decision support for Canadian homeowners. It does not estimate individual cancer risk, replace medical advice, certify a specific consumer product, or provide a DIY radon-mitigation installation procedure.