A Health Canada report has found that one in five Yukon homes contains more than the acceptable level of carcinogenic radon gas.
That rate is among the highest in the country.
The survey tested 14,000 homes across the country, including 228 in the Yukon.
Only Manitoba and New Brunswick homes tested above the higher-than-acceptable level more frequently.
Six per cent of Yukon homes showed over three times the recommended safe concentration.
Radon is a gas that occurs naturally as a result of decaying uranium. It can seep into homes through cracks in the foundation, and becomes dangerous with prolonged exposure.
Health Canada estimates that a non-smoker exposed to high concentrations of the gas over their lifetime has a five per cent chance of developing lung cancer. For smokers, the risk increases to one in three.
Remediation on homes found to have elevated levels could include sealing the basement against leaks and improving ventilation.
A Yukon government program announced in 2008 allows residents to borrow testing equipment to assess their risk.