How to detect radon in your home

To better understand what radon is, read our article Radon and its effects on health.

Where to find a Health Canada-certified dosimeter?

You can easily purchase a certified dosimeter: 

• Online at the CAA-Quebec Boutique
• At one of the 13 CAA-Quebec Travel Centres
• At select hardware stores or big-box retailers

The websites of the Canadian Association of Radon Scientists and Technologists (CARST) and Take Action on Radon also offer radon measurement kits for purchase. 

What types of dosimeters are available?

Several types of dosimeters are available for measuring radon, depending on the duration of the test and the level of precision required. 

Short-term test (activated charcoal)

• Duration: 2 to 7 days
• Fast results
• Useful for an initial risk assessment or before purchasing a home
• Provides a one-time reading that is less representative of actual exposure

This type of test is convenient but does not always reflect the annual average radon level in a home. 

Electronic radon monitor (ERM)

• Duration: 3 to 12 months
• Continuous data
• Real-time tracking of concentration changes
• Enables more detailed analysis over time

It is recommended to use a device tested under the Canadian National Radon Proficiency Program (C-NRPP). 

Long-term test (dosimeter)

• Duration: 3 to 12 months
• Measures average concentration over an extended period
• Results representative of actual radiation exposure
• Laboratory analysis required

The long-term radon test is generally considered the most reliable way to assess indoor radon levels. The Acustar AT100 (dosimeter available at the CAA-Quebec Boutique) and the Pro-Lab RL116 are recommended by Health Canada. 

How much does a radon test cost?

In Canada, the purchase price of a radon test kit is generally between $30 and $75, and up to $150 to $350 for an electronic monitor, depending on the type of device and measurement duration. 

When should you test for radon?

Winter—more specifically between October and April—is the best time to conduct your radon test. Since windows and doors remain closed and ventilation is at a minimum, radon concentrations are generally higher. 

What is the ideal location for installing a dosimeter?

To obtain a reliable measurement of radon levels in your home, choosing the right dosimeter placement is essential. Here is where and how to install it for representative results: 

• In the basement, if you spend more than four hours there each day (bedroom, family room, or home office).
• On the main floor, if your home has no basement or if the basement is rarely used.

Place the dosimeter on a desk, table, or shelf, or suspend it from the ceiling with a cord if necessary: 

• Approximately 40cm from an interior wall or 50cm from an exterior wall
• Between 0.8 and 2m from the floor, but at least 50cm from the ceiling
• 20cm away from any other object to ensure adequate air circulation

Where should you avoid placing a dosimeter?

Certain locations should be avoided to prevent skewing radon readings: 

• Kitchen
• Laundry room
• Bathroom
• Closet or cupboard
• Sump pit, crawl space, or foundation recess
• Near heating, ventilation, or air-conditioning ducts
• Near doors, fans, windows, or chimneys
• Near any electrical or electronic equipment

• In direct sunlight

Several factors can influence radon levels in a home: 

• Soil composition
• Degree of ventilation maintained in the home
• Condition of the foundation
• Barometric pressure
• Weather Conditions
• Etc.

Where do you send a radon test for analysis?

The dosimeter packaging includes all instructions for sending it to the laboratory. Simply package the dosimeter using the materials provided and send it in for analysis. Results from a long-term test are generally available within a few weeks. 

What is an acceptable radon level in a home?

According to Health Canada, an acceptable radon level in a home is below 200 becquerels per cubic metre (Bq/m³). In Quebec, the average in basements is approximately 35Bq/m³. 

However, corrective or mitigation measures to reduce radon levels are recommended if the annual concentration in occupied spaces exceeds 200Bq/m³: 

• Up to 600Bq/m³, remediate within 2 years.
• Above 600Bq/m³, take action within 12 months.

How do you convert becquerels to picocuries?

Picocuries (pCi) are another unit used to measure radon, particularly in the United States. 

1 pCi/L ≈ 37 Bq/m³ 

Mitigation measures are therefore recommended above 5.4pCi/L. 

CAA-Quebec recommends using Health Canada-certified tests. 

When should you call a professional to test for radon?

It is best to call a professional to test for radon when results exceed 200Bq/m³ or if you are not comfortable conducting the test yourself. 

Professionals use specialized equipment, such as electret ion chambers, digital monitors, and continuous radon monitors. These tools can be used for both short- and long-term tests. 

FAQ – Radon detection

1. Can you run an air exchanger during a radon test?

It is best not to run the air exchanger during a radon test, as it may skew the results. The goal is to measure the natural radon concentration in the home. 

2. Should windows be kept closed during a radon test?

Yes. Windows must remain closed for the entire duration of the test. This is why it is recommended to test in winter, when openings are limited. 

3. What radon level is considered safe in Canada?

In Canada, a radon concentration is considered acceptable when it is below 200Bq/m³ (approximately 5.4pCi/L). Above this threshold, mitigation measures are recommended. 

Once radon gas has been detected, here is what to do if radon levels are too high.