Why decades in one home, more hours at home after retirement and age at diagnosis make radon matter for older Canadians, and what the evidence says.
Photo: Shixart1985, CC BY 2.0, cropped, via Wikimedia Commons.
6,200
hours a yearTime at home for people working from home, retired or on leave, against about 5,205 hours for people working or in school, from 1,128 Canadian radon test participants who kept a diary.
The evidence does not show that radon is more harmful to older people. What changes later in life is time: more years in one home, and more hours in it each day after retirement. Lung cancer in Canada is mostly diagnosed in adults aged 50 and older. See how radon causes lung cancer.
In a Canadian study, people who were retired, on leave or working from home spent more of the year at home than people who worked or went to school. Participants kept a record of their hours at home. That group spent roughly 1,000 more hours a year at home than people working or in school. These are hours at home, not a measured dose.
A separate study of 4,009 Canadian households looked at what happened when the pandemic moved people indoors. Time in the main home rose from 66.4% to 77% of their time. The yearly radon dose rose 19.2%. That finding is about the pandemic, not about retirement. See how to run a long-term test.
Radon risk builds with years of exposure. The European pooled analysis of 13 studies found no evidence that the proportional increase in risk from radon varied by age, sex or smoking history.
16
%Increase in lung cancer risk per 100 Bq/m³ of long-term radon exposure, after correcting for measurement error (8.4% on measured concentrations), in the pooled analysis of 13 European case-control studies. The relationship is linear, with no threshold, and significant below 200 Bq/m³.
The proportional rise is the same at 35 as at 75. What changes with age is circumstance, such as more years in the same home and more hours in it each day. See what 200 Bq/m³ means for your home.
In Canada, almost all lung cancer is diagnosed at 50 or older. Half of cases are found at Stage IV, and five-year survival is about 19%.
98
%Share of lung cancer cases in Canada that occur in adults aged 50 and older, according to the Public Health Agency of Canada.
Health Canada says radon is the leading cause of lung cancer in never-smokers. It is behind about 16% of lung cancers, more than 3,000 deaths a year. That does not mean radon caused any one case.
About 2% and 17%
Health Canada's modelled lifetime risk of lung cancer at the 200 Bq/m³ guideline level, for a person who never smoked and for a smoker. It rises to about 5% and 30% at 800 Bq/m³, against a baseline of about 1% for a never-smoker. Population estimates from a model, never an individual's risk.
The WHO handbook puts former smokers’ radon risk between the risk for current smokers and for never-smokers. The 2024 Cross-Canada Radon Survey says a different risk is anticipated for people exposed to tobacco smoke, asbestos or combustion particles. It says the same for people who have had tuberculosis, COPD or severe pneumonia, and asks them to test where they live. The survey calls this risk anticipated, and no study has shown that COPD makes radon more dangerous. See how smoking and radon act together.
A test today shows the radon you still breathe, even after decades in one home. It cannot show past levels. No level is risk free, and lowering a high level still lowers your future risk. It also protects children and grandchildren who live in or visit the home.
Health Canada recommends a long-term test of at least three months in fall or winter. Place the detector on the lowest level where someone spends four or more hours a day.
1
yearTime within which Health Canada recommends corrective action when a long-term test of 91 days or more is above 200 Bq/m³, and sooner the higher the level.
Retirement is not one of Health Canada’s reasons to retest. In our view, the extra hours at home after retirement are a reason you may choose to test. Retest after changes to the home, too. Check whether a change means you should retest.
Building age alone does not decide the radon level, the 2024 Cross-Canada Radon Survey found. In the Canadian study of hours at home, homes built from 2006 to 2020 had the highest measured dose rates on average, and older homes lower. That is a group average and says nothing about a single house.
Health Canada lists insulating, air sealing, new windows, a finished basement, a new furnace or foundation work since the last test as reasons to retest. Health Canada’s radon guideline applies to any part of a building where people spend more than four hours a day, which includes long-term care residences. See how radon is handled in care homes and seniors’ residences.