Radon guideline

The Canadian guideline for radon is 200 becquerels per cubic metre (Bq/m³).

Health Canada collaborated with the Federal Provincial Territorial Radiation Protection Committee (FPTRPC) to review the health risk from exposure to radon. The risk assessment was based on scientific information and was the subject of broad public consultation. We developed the guideline for exposure to radon in indoor air using both the risk assessment and feedback obtained from the public consultation. We will review and update it as appropriate.

It's possible to reduce high levels of radon using corrective actions. We recommend that:

  • you take corrective action if the average annual radon level exceeds 200 Bq/m³ in the normal occupancy area of a building
  • you take corrective action sooner, the higher the radon level is
  • the corrective action should reduce the radon concentration as much as is practicable
  • the construction of new buildings use techniques that minimize radon entry and will help remove radon after the construction is finished, if necessary

What the guideline includes and excludes

In addition to residential homes, this guideline applies to public buildings and workplaces with an occupancy of more than 4 hours per day. This includes:

  • schools
  • hospitals
  • long-term care residences
  • other indoor workplace settings

This guideline excludes:

Normal occupancy area

The "normal occupancy area" refers to any part of the building where a person is likely to spend more than 4 hours per day. This would include a finished basement with a family room, guest room, office or work shop. It would also include a basement apartment. It would exclude:

  • a crawl space
  • an unfinished basement
  • any area that is normally closed off or accessed infrequently, such as a:
    • cold room
    • storage area
    • furnace room
    • laundry room

Corrective action time frame

You should complete corrective actions :

  • in less than 1 year if the radon level is greater than 600 Bq/m³
  • in less than 2 years if the radon level is between 200 Bq/m³ and 600 Bq/m³

As much as is practicable

"As much as is practicable" refers to what you can achieve with standard radon reduction methods in a cost-effective manner. This is consistent with the ALARA (as low as reasonably achievable) principle, where you make reasonable efforts to maintain radiation exposures as low as possible, while considering social and economic factors. In most situations, you can readily achieve a final level less than 200 Bq/m³. In a very small number of cases, the residual radon level may be greater than 200 Bq/m³ despite all reasonable corrective actions. It is not the intent of this guideline to recommend excessive or unreasonable costs for corrective actions. Such situations should be managed on a case-by-case basis to achieve the right balance of all costs and benefits for homeowners and occupants.

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