A new study from the University of Calgary shows that the levels of radon found in new Canadian homes has risen significantly over the past 50 years, from 96 Bq/m3 (Becquerels per cubic metre) in the 1970s, to an average of 131 Bq/m3 in the 2010s.
The study, published in Scientific Reports, compared the levels of radon gas found in Canadian residential buildings with those found in Sweden. The team studied more than 25,489 Canadian buildings and 38,596 Swedish buildings constructed since 1945.
It found that while radon levels were comparable in the 1970s and ‘80s, those levels have steadily decreased in Sweden, while Canadian levels now soar 467% above equivalent Swedish buildings.
The Risks of Radon
This naturally occurring radioactive gas is everywhere, releasing when uranium in the earth decays. “When radon is released from the ground into the outdoor air, it is diluted and is not a concern” says Health Canada. “However, in enclosed spaces like homes, it can accumulate to high levels.”
Radon exposure is the second leading cause of lung cancer in Canada, and the leading cause of lung cancer in non-smokers, says Lung Cancer Canada.
Study authors Selim M. Khan et al. note that “Canada’s annual rate of new lung cancers is currently 163% greater than that of Sweden,” despite the country having similar smoking rates. One suggestion from the study’s findings is that our built environments might be contributing to those higher rates.
A Possible Link to Building Performance
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Associate dean of the U of C’s School of Architecture, Planning and Landscape Joshua Taron says:
“Canadian construction and design practices in the last 40 years have produced residential, commercial and industrial buildings that capture, contain and concentrate radon to unnatural and unsafe levels.”
Causes of this rise in radon levels are complex, but could include factors such as the types of heating and ventilation systems Canadians have been adopted, especially in the context of new building performance standards. The study indicates the need for further study, but argues that these rising levels need to be tackled quickly.
The study authors predict that “(without intervention) the average Canadian residential radon level will increase to 176 Bq/m3 by 2050.”
Health Canada’s guideline for indoor radon exposure is 200 Bq/m3. Khan et al. caution that “100 Bq/m3 marks an exposure at or above which an increased relative lifetime risk of lung cancer is statistically significant.”
Urging immediate action, the research team recommends introducing radon mitigation measures into the national building code.
Image credit: Blake Wheeler
