The Environmental Protection Agency has warned that the number of homes in Ireland at risk from radon, a cancer-causing gas linked to 350 new lung cancers each year, is significantly higher than previously thought.
New radon maps to be launched the EPA predict as many as 170,000 homes are now at risk, up 45,000 from previous estimates made 20 years ago.
An EPA spokesman told RTÉ Morning Ireland that almost half a million Irish citizens are living in houses that could potentially be at risk of having radon.
Radon is a colourless, odourless, and tasteless, naturally occurring radioactive gas. It is released by the decay of uranium in rocks and soils.
If we breathe enough of it in, over a long period of time, it can damage DNA in our lungs and increase our risk of lung cancer.