Infants and children are particularly sensitive to the negative health effects of the alpha particle radiation emitted by radon gas, and special measures should be taken to reduce their exposure as much as possible.

• Children’s organs are still developing. Rapidly growing tissues and cells are very vulnerable to DNA damage from radiation exposure, as their DNA is being replicated. Any resulting genetic mutations can be propagated to all cells arising from the damaged cell.
• Children weigh less, and so their overall exposure (i.e. the amount of radon they absorb per kilogram of body mass) is much greater compared to an adult.
• Children breathe faster. An infant or small child will respire 2-3 times faster than adults as they have little lungs and are often more active. Faster breathing means more radon exposure.
• Children have more life left. Radon exposure causes DNA damage and genetic mutations that may take 10-30 years before lung cancer is diagnosed. Early life radon exposure means a person is more likely to live long enough to get cancer from it.

In terms of lifetime relative risk of developing lung cancer, a child exposed to 1,000 Bq/m³ radon from birth to their 6^th birthday (5 years) has already inhaled the equivalent of a lifetime breathing in air with 200 Bq/m³ radon.

^{Reference: Chen, J. Canadian Lung Cancer relative Risk from Radon Exposure for Short Periods in Childhood Compared to a Lifetime. Int. J. Environ. Res. Public Health 2013, 10, 1916-1926.}