Find out how to test your home for radon here.
Some 170,000 homes across the country are at risk from a cancer-causing radioactive gas, according to the Environmental Protection Agency.
The watchdog has today published a new map of areas impacted by radon - the first update in two decades.
The EPA said that another 45,000 homes had been added to inventory for radon exposure since the last estimate 20 years ago.
Radon, a gas that originates from the decay of uranium in rocks and soils is a cancer-causing radioactive gas.
Every year in Ireland 350 new lung cancer cases are linked to exposure to radon, which has no taste, smell, or colour, the EPA said.
The EPA says testing for radon is simple, and it has launched a new radon maps which shows where the problem may lie.
Senior scientist with the EPA, David Fenton, says it's a significant public health risk and people need to act:

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