Remedial Action

WHAT IS REMEDIAL ACTION? 

If radon levels are above the Canadian Guideline, Health Canada recommends that actions be taken to reduce the levels of radon to less than 200 Bq/m3 within two years of the test date.  There are many techniques that are used to reduce radon levels.  Two of the most widely used methods are: 

• Active sub/slab depressurization - most commonly used. This method involves installing a pipe through the foundation floor slab and attaching a fan that runs continuously to draw the radon gas from below the building and release it into the outdoors where it is quickly diluted. 

• Active sub-membrane depressurization – used for crawlspaces.  This method involves laying a thick plastic sheet (often a polyethylene membrane) over the soil, sealing the air-tight membrane to the foundation walls and placing a pipe with fan through it to draw the radon from under the plastic sheet and vent it to the outdoors.

• Increasing mechanical ventilation of the building - A heat recovery ventilator (HRV) or energy recovery ventilator (ERV) can be installed to increase ventilation, which will help reduce the radon levels. An HRV increases ventilation by introducing outdoor air as it uses the heated or cooled air being exhausted to warm or cool the incoming air. It is important to ensure that this type of system has balanced intake and exhaust air flows so that the building is not depressurized, which can draw in more radon.