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Canadian Association of Radon Scientists and Technologists

Helping Canadians Reduce Radon Risk






Four steps to Reduce your Radon Exposure:

No area is RADON free – All Homes and Buildings need to be tested for Radon.

Radon is an invisible, odorless, tasteless gas. 

The only way to know the radon level in a building (home, school or workplace) is to test.

New homes and older homes, all need to be tested for radon.

If you build a new home, we recommend testing the first heating season in the house.

Contact one of our members to help.



Long-Term Testing

A long-term test is a test that lasts for more than 91 days.  It can be from 91 days to one year.

A long-term test provides a year-long average of your radon exposure. Radon levels can fluctuate on a day to day and season to season basis.  A long-term radon test provides an average level. 

This testing also provides information on how your home’s radon levels put you at risk for lung cancer, since prolonged exposure to radon increases risk of lung cancer.                                                                   

If you do the test yourself, make sure your read the instructions to understand the best duration for the radon test you have purchased.

Short-Term Testing

A short-term radon measurement provides quick results.  These tests must be a minimum duration of 48 hours 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 a long-term test be conducted before making a decision to mitigate.


Post Mitigation Radon 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.  The test duration should last for a minimum of 48 hours.

The homeowner should then follow up with a long-term test during the next winter season after the mitigation system was installed.

The radon measurement device must stay in location for the duration of the test and then be returned to the lab for analysis.  Ensure that you keep the return packaging for the device to return to the lab it was purchased from. 

Mark the date to return to the lab, or call your professional to come back and pick it up at the end of the testing period.

The laboratory will report your radon test results after analyzing the device.

Health Canada has set a guideline of 200 Bq/m3 which they would like all Canadian buildings to be reduced below.  The health risk from radon is lower if levels are below 200 Bq/m3. While it is possible to reduce the radon level and the association health risk even lower, at levels below 200 Bq/m3 Health Canada considers that it is up to the homeowner whether to reduce the radon levels further.

If the long-term measurement results are greater than 200 Bq/m3, then Health Canada has provided some suggestions of time frames for mitigation.

 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

     Note:  Average outdoor radon concentration=15 Bq/m3 

If you have tested your home and discovered it requires radon mitigation, hire a C-NRPP Mitigation Professional with proper training and hands-on experience to reduce the radon levels.

Radon Mitigation can include measures which will include sealing, removing or ventilating.

Sealing the building foundation will attempt to prevent radon entry.

Removing radon from below the building to reduce the amount of radon entering the building from ground contact.

Ventilating the building air will provide dilution of the inside air reducing radon concentrations.

Active Soil Depressurization (ASD) - a radon mitigation system which removes the radon from below a building and provides a pathway for it to exit outside.    ASD is the most effective method of reducing radon levels in a home.


In Health Canada’s Active Soil Depressurization (ASD) Field Study of 52 homes, 

they found a 90.7% reduction in radon with an ASD system.

http://www.hc-sc.gc.ca/ewh-semt/radiation/radon/active-soil-depressurisation-2016-depressurisation-active-sol-eng.php




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