Short answer
Radon causes lung cancer at any age, but there is no good breakdown of radon harm by age at exposure, and the risk models are built mostly on adults. What’s known: children’s lungs receive a higher estimated dose from the same air, they have the most years for damage to play out, and the effect takes decades to show. Older adults accumulate long exposure at home. Testing early matters most for infants and children.
Key facts
- Radon’s established health effect is lung cancer. Childhood exposure usually shows up in adulthood.
- Children’s smaller lungs and faster breathing give a higher estimated dose from the same air (ATSDR).
- A Canadian risk study built on the EPA model applies no childhood adjustment, because childhood data are sparse.
- About 90% of radon-induced lung cancer risk is estimated to come from exposure at home (Health Canada scientists).
What the data does and doesn’t cover
Radon risk estimates come mainly from studies of underground miners, almost all adults exposed to far higher levels than any home, and from pooled studies of people with and without lung cancer in homes. Neither group was designed to answer “how harmful is radon at age 2 versus age 70?” The headline Canadian figures, 16% of lung cancer deaths nationally and about 850 a year in Ontario, are population totals, not broken down by the age at which people were exposed. A Canadian risk study built on the U.S. EPA model applies no separate adjustment for childhood exposure, because the data on it are sparse and the uncertainty is larger.
So the honest summary is a mix: some facts are established, some are well-reasoned estimates, and some are open. The table separates them.
| Age group | What’s known | What’s uncertain | What to do |
|---|---|---|---|
| Newborns and infants (0–2) | Smaller lungs and faster breathing give a higher estimated dose than an adult gets from the same air (ATSDR). Many hours a day are spent in one room, often the nursery. | How much extra lifetime risk this adds. | Test before the baby comes home. See the newborn checklist. |
| Children (3–17) | They have the most years ahead for damage to develop. Exposure from childhood adds to the lifetime total. | Whether children are more sensitive per unit of dose. Some dosimetry work suggests so; the epidemiology is sparse. | Test the bedroom level and playroom. Mitigate above 200 Bq/m³, and consider it above 100. |
| Adults (18–64) | Most radon-related lung cancers are diagnosed later in life, after decades of exposure. Smoking multiplies the risk: about 2% lifetime for never-smokers vs about 17% for smokers at 200 Bq/m³. | Exactly how exposure at different ages combines. | Test, fix, retest. Stop smoking. |
| Older adults (65+) | Long cumulative exposure, often many hours a day at home. In a study of the general population, risk kept rising with the duration of exposure, including beyond 40 years. | The benefit of lowering radon in absolute terms is generally smaller than for a child, since cancer takes years to develop. Lowering radon still lowers risk. | Test the rooms you live in, especially a basement suite or bedroom. See the older adults checklist. |
Babies and children
Two features of young children matter for radon. First, dose: a child’s lungs are smaller and they breathe faster for their size, so the estimated radiation dose to the lung from a given level of radon is higher than for an adult. Second, time: a child has the longest remaining life, and so the longest window for damage to be copied, accumulate and turn into disease. Because the effect takes years to decades to appear, children exposed at high levels aren’t expected to show it as children.
What about other complications? Lung cancer is the only established health effect of radon in homes. Research on other childhood conditions hasn’t shown a clear link at household levels, and you shouldn’t read a child’s coughs or colds as a sign of radon. That’s part of why the harm is so easy to miss: there’s no early warning for a parent to notice, which makes the test the only protection.
A practical way to think about it: radon exposure starts counting from the first day a baby is home. A nursery in a basement at 300 Bq/m³ is adding to that child’s lifetime total every night. Finding that out before the baby arrives, rather than after, is the main point. The newborn checklist works backwards from the due date.
Adults
Most of the exposure that produces radon-related lung cancer is the exposure of ordinary adult life: decades at home, at moderate levels. A study of Ontario estimated that most radon-related cancers come from homes below 200 Bq/m³ simply because there are so many of them. For adults, smoking status is the single biggest factor. For a person exposed to 200 Bq/m³ over a lifetime, Health Canada puts the risk at about 2% for a never-smoker and 17% for a smoker.
Older adults
Three things stand out for older adults. They often spend most of the day at home, and Health Canada scientists estimate that about 90% of radon-induced lung cancer risk comes from exposure at home. Their exposure has already been long, and a study of the general population found risk kept rising with the duration of exposure, including beyond 40 years. And a basement suite or a main-floor bedroom added for stairs-free living can put someone in the lowest, highest-radon level for most of the day.
The honest counterpoint is that the benefit of lowering radon in absolute terms is smaller for someone with fewer years ahead, since cancer takes years to develop. Smokers and former smokers, who are at much higher risk, and anyone who expects many more years at home, still gain from it. The older adults checklist covers what to check.
The same message at every age
- The damage is cumulative and can’t be undone, so the earlier radon is lowered, the more you avoid.
- Radon doesn’t cause symptoms, so a result of “nobody has been sick” tells you nothing.
- The room that matters is where each person spends the most hours: a nursery, a child’s bedroom, a basement suite, a home office.
- One long-term test covers everyone in the home. Retest after renovations that change the foundation or airflow.
Common questions
Are children more at risk from radon than adults?
Children are expected to receive a higher dose to the lungs from the same air, and they have more years for damage to develop. Whether they are more sensitive per unit of dose is still uncertain, because most radon research is on adults. Health Canada’s guideline applies to everyone, and testing early protects children for the longest.
Can radon cause illness in babies and children right away?
Lung cancer is the established health effect of radon, and it takes years to decades to develop. Research hasn’t shown a clear link between household radon and other childhood conditions, and radon doesn’t cause short-term symptoms.
Is radon worse for older people?
Not necessarily. Older adults often spend many hours at home and may have a long history of exposure, and smokers and former smokers are at higher risk. Lowering radon still lowers future risk at any age.
Does age change what radon level is safe?
Health Canada’s guideline is 200 Bq/m³ for everyone, with a note to keep levels as low as reasonably achievable. No safe threshold is known, so many families with children choose to mitigate between 100 and 200 Bq/m³.
Sources
- Health Canada — Radon: Is it in your home? Information for health professionals
- ATSDR (U.S. CDC) — Radon: clinician brief, including exposure in children
- Int. J. Environ. Res. Public Health (2013) 10(5):1916 — radon lung cancer risk model for Canada, including childhood exposure
- National Research Council — Health Effects of Exposure to Radon (BEIR VI), risk models and time since exposure
- Science.gc.ca — A Calculated Risk: Radon Exposure in Indoor Environments
- Duration versus intensity of exposure on the risk of lung cancer due to radon exposure in the general population
- CMAJ (2023) — Radon is responsible for 16% of lung cancer deaths in Canada
- Peterson et al., Cancer Causes & Control (2013) — Lung cancer risk from radon in Ontario