Over 180 homes across Ireland have been found with high levels of the cancer-causing gas, radon.
According to the Radiological Protection Institute of Ireland, four homes have been identified with particularly high radon levels, between 10 and 22 times the acceptable level in the past eight months.
In addition, 25 homes recorded up to ten times the acceptable level.
Radon is the second biggest cause of lung cancer after smoking and is directly linked to some 250 lung cancers in Ireland each year.
The homes in question were: two in the Ballindooley and Castlegar, Co Galway; one in the Campile area of Co Wexford; one in Ballisodare, Co. Sligo. The families living in these homes would have received a radiation dose equivalent to up to 15 chest X-rays every day.
In addition, 25 homes with up to ten times the acceptable level were identified in Dublin (1), Galway (8), Kerry (4), Mayo (2), Sligo (2), Tipperary (1), Waterford (2) and Wexford (5).
The remaining 152 homes had radon levels up to four times the acceptable amount and were found in high radon areas throughout the country.