Why researchers say lowering Canada’s radon limits could prevent more lung cancer cases and save lives
When Maureen Hayes first tested her Ottawa home for radon a little more than a year ago, the initial readings were far below Canada’s current limits to take action.
His equipment showed 114 becquerel per cubic meter (Bq/m³), which was under the 200 Bq/m³ guideline for hiring a radon professional. According to Health Canada guidance.
But Hayes soon realized that the country’s recommended limit for this invisible, cancer-causing radioactive gas was actually twice as high as the World Health Organization (WHO). And as she kept testing, she saw levels in her home reach 180 Bq/m³ and above – still under Canada’s limits yet above WHO guidelines.
Hayes was concerned – and confused. “The government issues these guidelines,” she said, “but they differ internationally.”
after seeing CBC News coverage on radon Earlier this year, Hayes decided to install a $3,000 mitigation system to reduce her home’s radon levels and, in turn, reduce any exposure that could increase her risk of lung cancer. But she wasn’t the only one unsure about when to act, and some researchers say Canada needs an evidence-backed rethink of its radon guidelines in light of emerging research and increasing risks.
Health policy researcher Lisa Guay, who works as national policy manager for the David Suzuki Foundation, an environmental advocacy non-profit, said the current standard “fails to protect Canadians” who live in buildings that exceed levels that WHO considers safe.
“Canada’s radon guidelines are about to be updated,” he said. “Having higher guidelines may lead to some complacency and prevent remedial action, whereas lowering it would be cost-effective and have clear health benefits.”
Radon gas is invisible, poisonous and millions of Canadians have no idea it is hidden in their homes. For The National, CBC’s Lauren Pelley explains the health risks and what you can do to keep your home safe.
Guidelines last updated in 2007
The country’s radon guidelines were last updated in 2007, lowering the limit to 200 Bq/m³ from the previous 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 guidance levels at this time, the federal department told CBC News in a statement.
Given the low radon testing rates in CanadaThe department said its focus is on increasing awareness and getting every Canadian tested “rather than redefining the response level.”
But Gyu, who A. wrote 2015 report On the country’s last radon guideline update, it said it was essentially out of date from the beginning and confuses the message about what level of radon is dangerous.
“Unfortunately we found that just as the Canadian standard was being finalized, new research was coming out that was really pointing the finger at the extent to which high levels of radon were a significant risk to population health,” he said.
There is scientific consensus that long-term indoor radon exposure can cause lung cancer, with a growing number of global studies over the past two decades showing clear links.
WHO launched an international radon research project in 2005 and by 2009, Health body officially recommended Those countries aim for a national reference level of 100 Bq/m³, and “wherever this is not possible, the level chosen should not exceed 300 Bq/m³.” (Guidelines vary from country to country, with some European countries still using limits as high as 300–400 Bq/m³.)
That 2009 report cited pooled data from more than a dozen countries across Europe that showed the relationship between radon exposure and lung cancer risk was roughly linear, with the risk increasing 16 percent for each additional 100 Bq/m³ of radon in someone’s home.
Radon mitigation can save hundreds of lives
Several researchers told CBC News that these findings suggest that more cases of lung cancer could be prevented if Canadians were encouraged to reduce their home radon levels well below the current national guideline.
Lung cancer is the deadliest form of cancer in Canada, with approximately 30,000 cases per year and approximately 20,000 of them resulting in death. Its early symptoms are rare and it is often discovered too late, when the cancer has spread beyond the lungs. What is radon exposure responsible for? An estimated 3,000 of them diedDue to which it has become the second leading cause of lung cancer after smoking.
A Canadian study published more than a decade ago It is estimated that, according to current Canadian guidelines, more than 900 lives could be saved each year if all homes above the limit reduced their indoor radon levels to the same safe, heavily-diluted concentration as outdoor air.
The authors wrote that if the number of all households above the WHO limit were reduced, an additional 700 lives would be saved annually.
“It makes sense that if the regulatory level is lower, fewer people will have negative health consequences,” said Anne-Marie Nicol, a toxicology researcher and associate professor at Simon Fraser University.
With millions of Canadians living in homes with high levels of invisible and poisonous radon gas, CBC’s Lauren Pelley explains how to test for it and what to do if it’s found.
Half of Canadian homes have levels above WHO guidelines
2024 cross canada radon survey suggest that 20 per cent of detached homes in Canada may have radon levels exceeding 200 Bq/m³, while another 26 per cent may have levels between 100 and 199 Bq/m³ – meaning that close to half of all detached homes may have radon levels above the WHO guideline, along with many other types of housing.
Canada’s 200 Bq/m³ limit was set at a time when it was not clear we could effectively get homes below that level of radon with mitigation techniques, Nicol said in an email exchange with CBC News.
But that has changed. Health Canada says modern mitigation work can be done Dramatically reduce indoor radon levels Over 80 percent when done correctly.
“Now that we know it’s possible, there’s a good argument for revisiting the guideline and reducing it (to 100 Bq/m³) in Canada,” Nicol said.
‘No safe level of radon exposure’ in homes
Most radon mitigation systems consist of a pipe installed in the floor of the home’s foundation, along with a fan that draws radon gas from beneath the home and releases it safely outside before it accumulates inside the home.
An update to the National Building Code of Canada released in late December also requires newly built homes to include a passive radon stack, which works like a chimney to help reduce indoor radon buildup. That update still needs to be adopted by the provinces.
Health Canada also emphasizes that “there is no safe level of radon exposure” and encourages Canadians to “reduce radon levels as much as possible,” the department said.
Its guidelines on indoor radon levels balance health risk reduction with socio-economic considerations, “recognizing that the burden of reducing will generally fall on individual homeowners.”
Those costs can be steep. As previously reported by CBC NewsRadon mitigation work can range from $2,000 to $5,000 and sometimes even more. There are no federal grants to offset those costs, but rather a patchwork of non-profit and provincial programs that most homeowners have to pay out of pocket.
Nicol said more government aid for cash-strapped households could encourage homeowners to install mitigation systems to reduce their exposure, especially as more Canadians already take advantage of energy efficiency grant programs for air sealing, insulation and new windows and doors — home changes that, in turn, could actually trap more radon.
“It’s a little different because public health is here, and the people who give grants are here,” Nicholl said.
Researchers are studying how smoke affects radon exposure
Others say that to better deal with the radon issue, Canada still needs a more thorough understanding of how risks are developing inside millions of homes before making changes to the country’s approach.
Aaron Goodarzi, one of Canada’s leading radon researchers, said the limit of 200 Bq/m³ was chosen over many other countries in an era of “exceptionally clean air”.“Of course this is changing with time and climate change and the prevalence of wildfire smoke.”
Goodarzi’s team is studying radon exposure in individuals, and The next phase of his research Indoor air quality will also be tracked to determine the additional impact of increasingly common wildfires – as radon gas appears to hitch a ride on smoke particles, whether from fires or cigarettes.
“I always think of particulate matter as the taxi that carries radon into your lungs…the dirtier the air, the higher the radon dose,” he said. University of Calgary professor and scientific director of the Evict Radon National Study.
Based on the team’s research so far, Goodarzi expects the risk of radon-induced health problems to increase when non-tobacco sources of smoke are included.
“But we need to understand it,” he said. “And from there, maybe that’s when the conversation about shifting guidance happens in a more informed way.”
