Testing for Radon

Since long-term exposure to elevated levels of radon poses a serious health risk, and radon levels can change daily, it is best to test for radon with a long-term test of 91 days or more. For most single-family homes, duplexes or apartments, you only need to test in one room (for homes with larger square footage you may want to consider testing in two different areas).

It is also a good idea to measure radon levels before renovating your home to see if you should include a mitigation system in your renovation plans, as well as after any renovations that have changed your heating system or building envelope.

By hiring a C-NRPP certified professional to conduct the testing for you, you can ensure that tests are placed properly. A professional will provide you with the information you need in a way that is easy to understand so you can rest be assured of your family’s safety, and that of your home, for years to come.


How to test?

Pick a room, pick a spot, record the information!

Then return the test at the end of 91 days.


Health Canada has developed guidelines on how and where to place tests, and C-NRPP has developed a list of devices which meet the set criteria for use.  If you purchase a detector to place yourself, ensure it is on the C-NRPP list – it may have the C-NRPP logo on the device or check our list.

Each device should include detailed instructions on where to place the test and how to get the results. 

You can hire a professional who is certified with the Canadian National Radon Proficiency Program (C-NRPP)  to conduct the testing for you.  A C-NRPP Professional will ensure that your tests are placed properly and will provide you with the information in a way that is easy to understand.  The more you understand about Radon exposure the more you can ensure you and your home’s safety for the future.


Long-Term Radon Test – is a radon test which is of duration of 90 days or longer

  • Typical devices for Long Term Radon Test are alpha track and electret ion (confirm with the manufacture of each device or the Device Listing Below)

Short-Term Radon Test –is a radon test which is of duration of at least 48 hours but less than 3 months

  • Typical devices for short term radon tests are continuous radon monitors (CRM), Electret Ion (ES), charcoal canisters, liquid scintillation or alpha track (confirm with the manufacture of each device or the Device Listing below)

Note: C-NRPP recommends that a decision for mitigation be based on a long-term test as recommended by Health Canada .  C-NRPP acknowledges that Short Term Testing has a place in post-mitigation confirmation, real estate and when a more rapid indication of the radon concentration may be required. All short-term tests should be confirmed with a follow-up long term test to have an accurate representation of the average annual long term exposure & before a decision for mitigation is taken.   Please see C-NRPP’s statement on Short Term testing here. (link would be added to C-NRPP Communication Brief on Short Term Testing)


What tests should I use? 

C-NRPP Listed Professional Devices are devices which are listed by C-NRPP and approved for C-NRPP Measurement Professionals to use when conducting tests.  You can hire a C-NRPP Measurement Professional to test for your or purchase a test for a do-it-yourself measurement.  Look for a device that is on the C-NRPP list. 

The tests do not have any chemical or harmful materials inside which would be spilled if knocked over or touched.   For each of the devices, the manufacturer will provide instructions on how and where to place the test, how long the optimal duration for the test device is and how to receive the results of the radon test.

Long and Short term C-NRPP Listed Professional Devices will need to be analyzed by an analytical provider, and so the instructions should provide information on how to return the test for analysis.

In Canada radon is measured in becquerels per cubic meter.  (Bq/m3)

Becquerel is a measurement of radioactivity.  Therefore, a Bq/m3 provides a measurement of radioactivity in a unit volume of air.  This provides us with an understanding of how much radiation is present in an area.


How many tests do I need? 

For a single family home, duplex or apartment you only need to test in one room.  If your home has a large square footage you may want to consider two test to test in two different areas in the occupied area of your home.

Also: You may want to use 2 tests for better accuracy. 

When a professional conducts testing, they follow proper Quality Assurance protocols with duplicate tests to verify precision of tests.  If you hire a professional, they will make sure that this is included in their Quality Assurance protocols. If you do it yourself, you may want to use two tests. 


How long does the test need to be?

Long-term tests: This is a test that lasts for more than 91 days. It could be from 91 days to one year.

This type of test can be done using a long-term test device or homeowner’s can use a digital detector or home radon alarm which stays in a home for at least 91 days or longer.

The purpose of the long-term test is to provide an annual average of your radon exposure.  Since radon levels can change day to day and season to season a long-term test will provide you with an average of what the radon levels have been throughout those changes.

Also, since lung cancer risk increases with the prolonged exposure to elevated levels of indoor radon, testing using a long-term test will provide you with information to understand how your home’s radon levels are putting you at risk for lung cancer.


Short term tests: this is a test which is at least 48 hours but can last up to 91 days.

The purpose of a short-term test is to provide a faster result, than a long-term test can provide which can be useful for various situations.  Health Canada recommends that if you conduct a short-term radon test you follow up with a long-term test to base a decision to mitigate.   (C-NRPP Statement on Short-Term Testing April 2017)


Post Mitigation Test:  If you have installed a mitigation system into your home, a certified mitigator should do a short-term radon test to ensure the system is effective in lowering the radon levels in the home.  This can be done using a professional Continuous Radon Monitor, C-NRPP Listed Professional Device short term test device or with an Electronic Integrating Device, left in the home for a minimum of 48 hours.  Once you have conducted a short term test you should conduct a long-term test during the following heating season to confirm the effectiveness of the mitigation system.


Real Estate Decisions:

A person purchasing a home which does not have a radon mitigation system installed, may want to know if they will need to install a radon system once they move into the house.  A short-term test could be conducted to provide some insight as to whether a radon mitigation may need to be installed.  We recommend conducting a long-term test once you move into the new home to confirm whether or not a mitigation system is required.

It is important to note that a home can be fixed and so even if you aren’t able to conduct a radon test before you decide to purchase a house, you can measure the radon levels after you move in and there are methods that can be taken to reduce radon levels in homes once you move in.

If you are considering selling your home, you may want to consider conducting a long-term test and installing a mitigation system, if necessary, before listing your house for sale.  See CREA’s A Homeowner’s Guide to Radon.

Discuss this with your real estate agent, or contact the real estate association in your area


Quick Survey:

Sometimes a person wants a faster result to understand where the levels are at and a short-term radon test can provide you with a faster result than a long-term test.  It is important to understand that levels can fluctuate with different occupancy use, seasonally and with different wind conditions and so a long-term test should be used to determine the need for mitigation.


What does my test report mean?

The health risk from radon is lower if levels are below 200 Bq/m3 and therefore, Health Canada recommends that further action to reduce radon levels  is not necessary. It should be noted that, while the health risk from exposure at levels below the Canadian Guideline is lower, it may be possible to reduce it even further through installation of a mitigation system. It is the homeowner’s choice to  decide and reduce at the desired level of radon exposure..

If the long-term measurement results are greater than 200 Bq/m3, then Health Canada has provided some suggestions of time frames for mitigation, they also recommend that when mitigation measures are taken, they reduce levels to as low as practicable.


Radon Concentration Recommended Remedial Action Time
Greater than 600 Bq/m3 In less than 1 year
Between 200 Bq/m3 and 600 Bq/m3 In less than 2 years
Between outdoor levels and 200 Bq/m3 At homeowner’s discretion
Average Outdoor Radon Concentration


15 Bq/m3


Additional Recommendations:



Test is less than 91 days



If your test duration was less than 91 days, you may want to follow up with a long-term test conducted with a during the heating season, as per Health Canada Guidelines to base a decision of mitigation.


Test is conducted with more than 50% of the duration outside of the ‘heating season’ (October 1 – April 30)


If your test was below 200 Bq/m3 but conducted outside of the heating season of October to April, you may want to consider retesting.

Health Canada recommendations are that the test be conducted during the heating season from October thru to April.

If the test was conducted with windows open for a significant portion of the test days, you may want to consider re-testing.

Radon in Water.

Radon also may be present in the water supply of a home.  As the water is used in a home through a tap, shower, or appliance the water aerates and releases the radon into the air.

If you have tested your home air for radon and find that levels are elevated and you are on a system that uses water from a well, you may want to consider testing the radon levels in the water.