Radon Overview for Residential Dwellings
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Radon is a colorless and odorless radioactive gas that is produced by the decay of uranium that is found naturally in rocks and soil. As a gas, radon can move through the soil enabling it to enter the atmosphere or seep into buildings.
In outdoor air, radon gas is diluted; it does not pose a health risk to the public. However, radon can accumulate in homes. Depending on the accumulated radon concentration in the indoor air space, radon may or may not pose a health risk to the building occupants.
There is a national radon map that was produced by geoscientists in 2010. The map shows that radon levels can vary significantly across the NWT from the natural environment. The work highlights the importance of radon testing in buildings in NWT and across Canada. As shown in Figure 1 (below), environmental radon that accumulates in the indoor environment (a.k.a. building space) is a known and recognized health concern in NWT as it is across Canada.
Figure 1. Relative radon risk zones across Canada (Health Canada, 2012)
The increased lifetime risk of developing lung cancer is the main health risk associated with a high level of radon exposure in indoor air. This is the result of the impact of the radiation from inhaled radon gas and its damage to the cells in the lungs. The effect of the damage depends on the levels of the radon exposure and how long a person is exposed to the radon concentrations.
NWT has not estimated the burden of disease from radon in our population but a national modeling estimate published in 2012 estimated that indoor radon exposure causes about 16% of lung cancers in Canada (https://academic.oup.com/rpd/article/152/1-3/9/1596749).
Not all lung cancer deaths from radon are preventable by mitigation measures. Smoking causes a high proportion of lung cancers. Smoking and radon exposure together can increase the risk of cancer more than either separately.
Indoor radon exposure is very dependent on building characteristics. Radon, as a soil gas, can enter a residential home through any space or opening (see Figure 2) that contacts the soil around or underneath the dwelling.
Figure 2. Typical radon entry routes in two types of foundation walls (source: https://www.canada.ca/en/health-canada/services/environmental-workplace-health/reports-publications/radiation/radon-reduction-guide-canadians-health-canada-2013.html)
In the NWT, there are buildings that are raised off the ground on piles; this provides increased ventilation between the ground and the building. This type of building construction generally lessens the risk of radon exposure to the occupants.
Radon testing is the best way to determine if there is a radon exposure concern within the residential building.
It is recommended that homeowners repeat the test every five years (5 yr), or as living or environmental conditions change.
A new UK study (released in January 2022) on climate change and permafrost thawing says that the permafrost thaw may potentially expose people in the North to higher concentrations of indoor radon. Hence, this is a possible environmental change scenario for northerners living in the NWT.
The Canadian Guideline for indoor radon level is 200 Bq/m3 in homes and buildings.
Homeowners and residents can obtain a radon test kit to measure the level of radon in the building or home.
The owner or resident should follow the instructions that come with the radon test kit, especially regarding the placement of the test kit, test period, and submission of the radon detector unit for lab analysis.
Both short-term (minimum 2 days) and long-term (minimum 3 months) radon test kits are available. The long-term test kit is recommended for determining the indoor radon level in your home as the longer test period accounts for daily fluctuations and provides a better picture of what is happening with the indoor radon levels. Testing should be conducted in the coolest months of the year.
The Health Canada “Take Action on Radon” website (https://takeactiononradon.ca/test/radon-test-kits/) provides information for building owners and residents on how to obtain or order radon test kits.
Radon detectors do not contain toxic substances.
If your radon test result is above the Canadian Guideline of 200 Bq/m3, then Health Canada recommends that the homeowner should consult with a Certified Radon Mitigation Professional on how the indoor radon level can be lowered within the building. The higher the radon level, the sooner it is recommended that action be taken (see Figure 3, below).
Figure 3. Recommended action levels for indoor radon levels (source: https://www.canada.ca/en/health-canada/services/environmental-workplace-health/reports-publications/radiation/radon-reduction-guide-canadians-health-canada-2013.html)
A Radon Mitigation Professional is a person who is certified by the Canadian National Radon Proficiency Program (C-NRPP). If you need to consult with a Certified Radon Mitigation Professional near(est) you, please go to the following website: https://takeactiononradon.ca/protect/find-a-radon-mitigation-professional/.
Note: You may have to consult with a Certified Radon Mitigation Professional from another province or territory if there is no Professional listed for the NWT.
Homeowners are responsible for repairing or maintaining the residential dwelling, including taking action to reduce the radon level in the building to (or below) the guideline level.
It is recommended that new homes be tested for radon. New homes may have either a radon rough-in stub pipe or a radon rough-in extended pipe in place to facilitate the reduction of radon. For more information on the three levels of radon systems, please visit https://c-nrpp.ca/newhome/.
If you want more information on the radon topic, there are two websites to visit:
- Radon Reduction Guide for Canadians (https://www.canada.ca/en/health-canada/services/environmental-workplace-health/reports-publications/radiation/radon-reduction-guide-canadians-health-canada-2013.html)
- Take Action on Radon (https://takeactiononradon.ca/learn/frequently-asked-questions/)