Action to reduce the radon level should be taken in a home whenever the average annual radon concentration exceeds 200 Bq/m³ and the radon level should be reduced to a value as low as practicable.
The higher the radon concentration, the sooner reduction measures should be undertaken.
The following checklist of actions should be considered when your home tests above 200 Bq/m³:
If your home tests above the guideline you should hire a certified radon professional to determine the best and most cost effective way to reduce the radon level in your home. The most common radon reduction method is called sub-slab depressurization. With this solution a pipe is installed through the basement sub-flooring to an outside wall or up through to the roof line with a small fan attached which draws the radon from below the house to the outside before it can enter your home. This type of system can reduce the radon level in a home by over 90%. Increasing ventilation and sealing major entry routes can also help reduce radon levels but their effectiveness will be limited depending on how high the radon level is and the unique characteristics of each home.
Examples of venting options for active sub-slab depressurization
Homeowners should take action to reduce the radon level in their home if it is above the Canadian guideline level. This image describes the most common radon reduction method called active sub-slab depressurization. This method involves inserting a pipe through the foundation floor slab into the granular material underneath the home. This image shows two homes with different venting options. One home has the pipe extended from the foundation floor slab hole to an outside wall at ground level, with a radon exhaust fan attached that is located near an outlet for power supply. The second home has the pipe extended from the foundation floor slab hole up through the house to the roof with the exhaust fan attached to the pipe in the attic of the home near an outlet for power supply. In both cases the fan draws the radon from below the home and releases it into the outdoor air before it can enter the home, significantly reducing the amount of radon in the home. It is important to ensure that the exhaust pipe is tightly sealed to make sure that proper suction is achieved and that radon gas is not being released back into the home.
Health Canada recommends that homeowners consult with a certified radon professional to determine the best radon reduction method. As with any service agreement or contract, caution is recommended and references and certification should be verified.
For more detailed information on radon reduction solutions Health Canada, in partnership with experts in radon mitigation, developed the following publications: