Why researchers say lowering Canada's radon limit could prevent more cases of lung cancer and save lives
CBC
When Maureen Hayes first tested her Ottawa home for radon a little over a year ago, the initial reading was far below Canada's current threshold to take action.
Her device showed 114 becquerels per cubic metre (Bq/m³), well under the 200 Bq/m³ guideline for hiring a radon professional, according to Health Canada's guidance.
But Hayes soon realized the country's recommended limit for this invisible, cancer-causing radioactive gas is actually double that of the World Health Organization (WHO). And as she kept testing, she saw her home's levels hit 180 Bq/m³ and beyond — still under Canada's threshold yet firmly above the WHO's guideline.
Hayes was concerned — and confused. "The government issues these guidelines," she said, "but they're different internationally."
After seeing CBC News coverage on radon earlier this year, Hayes decided to install a $3,000 mitigation system to slash her home's radon levels and, in turn, reduce any exposure that might heighten her risk of lung cancer. But she wasn't alone in being unsure about when to take action, and some researchers say Canada is overdue for an evidence-backed rethink of its radon guidelines in light of emerging research and rising risks.
The current standard is "failing to protect Canadians" who live in buildings that exceed a level that the WHO considers safe, said health policy researcher Lisa Gue, who works as the national policy manager for the David Suzuki Foundation, an environmental advocacy non-profit.
"Canada's radon guideline is due for an update," she said. "Having a higher guideline can lead to some complacency and prevent remedial action, when it would be cost effective to [lower it] and have clear health benefits."
The country's radon guideline was last updated in 2007, dropping the threshold way down to 200 Bq/m³ from the prior cutoff of 800 Bq/m³. (The measurement of Bq/m³ refers to the amount of radioactive radon gas present in a volume of air.)
Health Canada has no plans to change the country's guideline level at this time, the federal department told CBC News in a statement.
Given low radon testing rates in Canada, the department said its focus is raising awareness and getting every Canadian to test, "rather than redefining the action level."
But Gue, who authored a 2015 report on the country's last radon guideline update, said it was essentially outdated from the get-go and muddles the messaging on what level of radon poses a danger.
"Unfortunately what we found was that, just as the Canadian standard was being finalized, new research was coming to light that really put a finger on the extent to which higher levels of radon exposure were a significant risk to population health," she said.
There's scientific consensus that long-term exposure to indoor radon can cause lung cancer, with a growing body of global studies over the last two decades showing clear links.
The WHO launched an international radon research project in 2005, and by 2009, the health body officially recommended that countries aim for a national reference level of 100 Bq/m³, and "wherever this is not possible, the chosen level should not exceed 300 Bq/m³." (Guidelines vary among countries, with some European nations still using thresholds as high as 300-400 Bq/m³.)
