Health Canada’s radon gas exposure standards

In 2007, Health Canada revised the minimum radon concentration threshold downward from 800 Bq/m3 to 200 Bq/m3 to be closer to the thresholds established in Europe and the United States.

Radon gas is measured in becquerels per cubic meter (Bq/m3)

Permissible concentration standards for radon gas

New since April 2021 – The World Health Organization now recommends not exceeding the threshold of 100 Bq/m3 inside buildings to avoid prolonged exposure to radon and developing lung cancer
  • World Health Organization: 100Bq/m3 per day
  • Canada: 200Bq/m3 per day
  • United States: 150Bq/m3 per day
  • European Union: 300Bq/m3 per day for new buildings

How can Radon gas infiltrate my home?


Radon gas can seep from fractured bedrock, groundwater and soil. 

How do I know if the concentration of radon gas present in my home is too high?


There are two types of tests that measure the amount of radon gas in the air. A first test can be done short term (5 to 7 days) to detect the presence of radon.

A second test with dosimeter, over a period of 90 days, can measure the amount of radon (in bq/m3) present in the air.

At risk areas

Although Health Canada has targeted areas at risk of exposure, radon can be found almost everywhere in Quebec.

When should I test for radon in the air?



In the case of a new construction: we recommend carrying out a first measurement in the first year of residence. Since radon gas tends to seep into cracks and crevices in the foundation, it is important to give the house time to workso validation after 5 years is also recommended..

When you buy a house (regardless of the year of construction): to ensure that the air quality in your new property is optimal. The presence of radon gas cannot be considered as a hidden defect.