How to Test for Radon

HOW DO WE TEST FOR RADON? 

Radon can be found in any building across Canada, but the only way to know how much radon is in a building is to test. The source of most radon in public buildings is the soil on which the building is standing, and for that reason higher indoor radon levels are more likely to exist at the lower levels of the building (main floor, basements, crawlspaces).  As a result, Health Canada updated their guideline in 2016 to include testing of all occupied rooms that are on the main floor/basement/crawlspace areas that are occupied for 4 hours or more.

Radon levels in a building change significantly over time. They can rise and fall from one hour or day to the next and seasonally. For this reason, measurements taken over a longer period of time are more accurate. Health Canada recommends that radon testing in schools begin with a long-term test and be carried out for a minimum of 3 months during the school year in the fall and winter months. A minimum three-month test represents a person's annual average exposure and is used to determine if a building’s radon concentration exceeds the Canadian guideline level of 200 Bq/m³. 

To test for radon, Alpha Track Detectors or Electret Ion Chamber detectors are used to test for the radon alpha particles and its decay products.  To provide a representative radon concentration estimate for schools, measurements are made in the lowest-level occupied classrooms or offices of the building. An “occupied room” is one in which an individual spends more than 4 hours per day. Floors or walls that are in direct contact with the ground or a crawl space must be tested. Radon measurements in the building should be made all at the same time and be made in unoccupied rooms if there are plans for them to be occupied in the near future.   Radon detectors are left in place for 3-4 months, typically over the winter months when the building is closed up.  At the end of the test period the detectors are collected and sent to an accredited radon testing laboratory.  Test results are shown using the units of Becquerels per cubic meter (Bq/m3).     

INTERPRETATION OF RESULTS: 

If the long-term measurement results are below 200 Bq/m3 (Canadian Guideline), further measurements are not necessary. It should be noted that, while the health risk from exposure at levels below the Canadian Guideline is small, it may be possible to reduce it even further through remediation.

If the long-term measurement results are greater than 200 Bq/m3, then remedial action is recommended.