The number of Canadian homes with dangerous levels of cancer-causing radon gas has more than doubled in the past 12 years with some Calgary-area residents among the most at-risk.
Those are the findings of a study conducted by scientists including a University of Calgary researcher who say 18 per cent of households in the country require some kind of mitigation compared to 7 per cent found in a similar study in 2012.
“Alarmingly, this report concludes that Canadians are among the most highly radon-exposed people on earth, and that means we urgently need to address this to avoid a future of prevalent but otherwise avoidable lung cancers,” said the U of C’s Dr. Aaron Goodarzi, a radiation biologist.
That’s because Canada’s geology is heavy with radon-casing uranium.
The Cross Canada Radon Survey also shows one of the regions most impacted by the colourless, odorless radioactive gas that invades homes from the earth beneath them is the prairies where one in five homes are measured at or above 200 becquerels per cubic metres, or Bq/m³ – the level where mitigation is recommended.
Among jurisdictions where the gas is most prevalent are Strathmore, Okotoks and High River where a quarter to a half of households meet or exceed the 200 Bq level, says the report that collected 75,000 long-term radon readings from across the country.
“Many of these municipalities contain houses with average residential radon levels greater than 130 Bq/m³,” says the report.
“Therefore, we recommend that public health stakeholders who are active in these communities take particular care to increase the promotion of radon awareness and access to radon reduction resources at this time.”
The most impacted parts of the country are in the B.C. interior, the Yukon, Prairies and Atlantic Canada, the research found.
Reasons for those increasing numbers could be how homes are now built and the fact more people are testing for radon gas in their basements due to the increasing ease to do and the fact people are spending more time in that part of their homes, said Goodarzi.
A decade ago, it was estimated a new case of radon-related lung cancer arose every 23 hours in Alberta, he said.
“I think that number will be much higher now,” said Goodarzi, adding it’s believed 16 per cent of lung cancers in Canada are radon-linked.
The Canadian average for residential buildings is 84.7 but homes in Calgary and Edmonton have a a 1 in 6 chance on average of recording radon levels between approximately 80-110 Bq/m³ says the study.
“Two in five cases of lung cancer diagnosed in Canada today are of a non-tobacco origin, and one of the reasons for this is our record high exposure to other potent causes of lung cancer such as radon within the indoor air where we live, work and play,” said Goodarzi, who noted radon gas is the second-leading cause of lung cancer after tobacco use.
In a single larger jurisdiction like Calgary, the type of home construction is more important than its underlying geology in determining its radon gas risk, he said.
“It’s not where you are so much as the type of building – we don’t see a lot of neighbourhood-by-neighbourhood differences,” said Goodarzi, adding bungalows, with fewer windows, are likely to more effectively trap the gas than multi-storey homes.
But single detached and newer homes constructed to be more airtight are the most likely to have higher levels of the gas, say researchers who also say the potential danger exists in homes everywhere in Canada.
Higher levels of radon also tend to be present in rural areas that rely more on ground water sources and in areas with lower population density, says the study.
“Even for regions where average results indicate a lower incidence of elevated radon, there are houses containing radon at or above Health Canada and/or World Health Organization reference levels for radon action,” states the report.
The problem originates when uranium and thorium in rocks and soil break down, transforming into radium, a solid radioactive metal.
That metal then decays further into radon gas which combines with other gases in the soil to move quickly to the surface and enter homes, usually through opening in their basements.
Lungs are exposed to alpha radiation, which increases the likelihood of lung cells becoming cancerous.
Dust or smoke in a home tends to magnify the effect of the gas, say researchers.
Home testing can be done with what’s known as an ‘alpha track’ device, which uses no electricity and is often in the shape of an ant trap or small hockey puck.
It’s recommended mitigation be done when a reading surpasses 100 Bq/m³ – a permanent retrofit that’s effective and quick to install, says the report.
Goodarzi said he’s heartened by the strong possibility the next raft of Canadian building codes will include a requirement each new home built be equipped with a radon gas-detecting device.
“It’s fixable but you have to know you have a problem,” he said.
X; @BillKaufmannjrn