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What should households with children or pets know about radon?

What households with children or pets need to know about radon, which rooms to test first, and what the evidence on dogs and cats does and does not show.

A beagle asleep on a carpet.

Photo: Slyronit, CC BY-SA 4.0, cropped, via Wikimedia Commons.

Children do not usually get radon-related lung cancer while they are young. The risk from radon breathed in childhood shows up later in life. The evidence for dogs and cats is thin, and neither Health Canada nor the Canadian Veterinary Medical Association has guidance on radon and pets. One long-term test measures the air that everyone in your home breathes, people and animals alike. See how radon raises lung cancer risk.

Radon breathed in childhood adds to lung cancer risk later in life

Radon breathed as a child adds to the total exposure a person builds up over a lifetime. The sooner a high level in your home comes down, the less your children build up.

A Health Canada study is the only Canadian source that turns a few years of exposure before age 16 into a lifetime risk equivalent. Its figures compare one exposure with another and do not predict any one child’s health.

See how risk builds with exposure.

Health Canada’s childhood model does not treat children as more sensitive

The Health Canada study did not assume that children are more sensitive to radon than adults. Its author noted real uncertainty, because much of the evidence on childhood exposure comes from a study of miners.

The model gave a slightly higher lifetime risk for girls than for boys at the same exposure. Children also spend their days in schools and day cares, which have a page of their own. See how radon is handled in schools and day cares.

There is no established evidence that radon in the home harms a pregnancy

There is no established evidence that radon in the home causes miscarriage, birth defects or other pregnancy problems. A 2024 review found the evidence limited and inconsistent. It called for more research.

A pregnancy is still a good time to test. A long-term test runs for at least three months. That gives you an answer before the baby’s first winter at home. See how to run a long-term test.

Test the bedrooms on the lowest lived-in level first

Start with the bedrooms on the lowest lived-in level, the lowest floor where someone spends four or more hours a day. Health Canada recommends a long-term test of at least three months in the heating season.

  • Test first: a bedroom on the main floor or in the basement
  • Also a priority if children live in the home: a basement playroom
  • Skip: a kitchen, laundry room, bathroom or storage room

There is no separate test for pets. One test measures the air the whole household breathes. Find which room to put the detector in.

Dogs in high-radon areas had more lung tumours, but the study cannot prove cause

A 2020 US study found more lung tumours in dogs from the highest radon zone. It matched each animal’s zip code to US EPA county radon zones.

No one measured radon in any animal’s home, so the study shows an association. The authors concluded only that household radon might play a role. Laboratory studies at mining-level exposures produced respiratory tumours in dogs and rats. Those results do not predict the outcome for a dog living in a house.

Health Canada, the provinces and the Canadian Veterinary Medical Association have no guidance or position on radon and pets. There is not enough Canadian veterinary research to estimate the risk for pets here. See other radon claims we checked.

Radon causes no symptoms in pets or people, so only a test can tell

Radon has no colour, smell or taste. It causes no symptoms in people or animals, so only a test shows the level in your home.

The 2024 Cross-Canada Radon Survey found levels highest below ground, and says the difference comes from dilution on higher floors. A pet that spends most of its time in the basement spends it on the floor where levels are usually highest.

Radon by floor level

89.9, 68.8, 54.4

Bq/m³

Geometric mean radon levels below ground, at ground level and above ground, by the floor where the test was placed, in the 2024 Cross-Canada Radon Survey: 23.5% higher below ground than at ground level, and 20.9% higher at ground level than above. A population average, not a rule for any one home.

Date
2024-10-01
Sample
Not applicable
Source
Cross-Canada Radon Survey 2024 report, Version 1.1 (CCSR.24.1.1), October 2024
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The claim

“Radon sinks to the floor, where pets sleep.”

Our verdict

Not supportedRadon moves with air pressure, the stack effect and ventilation; it does not settle. Levels are highest below ground because upper floors are diluted by windows and doors.

The evidence

  1. 1. Radon by floor level (fact block)
  2. 2. Cross-Canada Radon Survey 2024 report, Version 1.1 (CCSR.24.1.1), October 2024
Checked

The claim

“Smaller pets get a bigger dose because their lungs are smaller.”

Our verdict

UnprovenNo veterinary study we reviewed supports it, including the 2025 review of radiation in companion animals; body size alone does not establish an animal’s radiation dose.

The evidence

  1. 1. Maipas et al. 2025, A mini-review of the potential health impacts of indoor radiation exposure in companion animals, Environmental Health Insights 19
Checked

See what to do after you get your result.

Sources

  1. 1. Health Canada, Radon action guide for provinces and territories: reduction actions
  2. 2. Chen 2013, Canadian lung cancer relative risk from radon exposure for short periods in childhood compared to a lifetime, IJERPH 10(5), Tables 1 and 2
  3. 3. Fowler et al. 2020, Ecological level analysis of primary lung tumors in dogs and cats and environmental radon activity, Journal of Veterinary Internal Medicine 34(6)
  4. 4. Cross-Canada Radon Survey 2024 report, Version 1.1 (CCSR.24.1.1), October 2024