A secondary school in Co Cavan has radon gas more than 13 times the safety level set by the Radiological Protection Institute of Ireland.
St Mogue's College, Belturbet, which has 189 pupils, is among 13 schools whose radon levels are so high that immediate remedial action needs to be taken, according to documents obtained by The Irish Times under the Freedom of Information Act.
The safety limit for radon gas, which can cause lung cancer, is 200 becquerels (bq) per cubic metre.
St Mogue's levels were measured at 2,688 bq in a survey carried out by the RPII last year. No one from the school was available for comment last night.
FCJ secondary school in Bunclody, Co Wexford, was next highest at 1,897 bq. Graiguenamanagh boys' school in Kilkenny was registered at 1,512 bq, while O'Carolan College in Nobber, Co Meath, was measured at 1,262 bq.
An assistant principal in the Department of Education said that dealing with the radon levels in the 13 schools was a matter of such urgency that a UK-based contractor should be employed to carry out the remedial work, even though this would "not be fully in line with normal procurement procedures".
The official urged the Department to address all 13 schools immediately, thereby ensuring that there could be no charge of failing to deal promptly with a significant health and safety issue, "particularly following the recent concern in schools over asbestos".
The fact that some schools have radon above the 200 bq mark was disclosed by the former minister for education and science, Mr Martin, last month. However, the names and locations of the schools with the highest measurements were not disclosed.
According to the documents, the Department of Education and Science has engaged the services of Mr Trevor Gregory, of the radon testing and mitigation section of Cornwall County Council, to eliminate the radon from the schools.
The documents contain a warning from the office of the Attorney General that a legal challenge to the State could arise if the Government does not disseminate sufficient information to the public about the dangers of radon gas.
The others schools identified as having significantly high levels of radon were: St Columba's, Tullow, Co Carlow; St Mogue's NS, Ballyconnell, Co Cavan; Clocher Uaithe, Piltown, Co Kilkenny; Bush Post-Primary, Riverstown, Dundalk, Co Louth; Rampark, Dundalk; Kilmainham Wood, Kells, Co Meath; Court NS, Gorey, Co Wexford; St Colman's, Ballindaggin, Co Wexford; and St Brigid's, Greystones, Co Wicklow.
Radon is a naturally occurring radioactive gas which is formed in the ground by the radioactive decay of uranium, which is present in all rocks and soils. If the gas enters an enclosed space, such as a building, it can rise to unacceptably high levels.