Some 11 employers in Kerry and Clare are to be prosecuted by the Radiological Protection Institute of Ireland (RPII) because of their failure to comply with a directive to carry out radon tests in their premises.
These will be the first prosecutions in Ireland and are also thought to be the first in Europe.
Summonses had already been issued to the Tralee and Ennis businesses, which included large as well as small employers, said Ann McGarry, chief executive of RPII, at the institute's fourth national radon forum in Tralee yesterday.
The summonses were being brought under the Radiological Protection Act 1991 (Ionising Radiation) Order, 2000.
In 2002 some 3,000 employers had been asked to carry out measurements in Kerry and Clare; those who had not responded to a directive got six months to complete measurements. Tralee and Ennis, both limestone areas, have emerged as high radon areas.
The fact that the underlying rock was not limestone was no guarantee of low radon; the institute had found high levels in areas where there was no limestone, and low levels in limestone areas. Dr McGarry also said basements and ground floors had the highest levels of the radioactivity.
The institute was baffled at the lack of public response to the potentially deadly gas, speakers told the audience of health workers, architects, engineers and public officials.
A house in Castleisland had shown one of the highest radon readings ever recorded. It was tested when two residents, both non-smokers, contracted lung cancer.
However, of 2,500 Castleisland householders written to by the institute in 2004 and advised to install a monitor, only 418 had requested radon test kits, some 385 returned the kits for analysis and of the 52 found to be above the safe reference level, only five undertook remedial measures, the forum heard.
Kerry North TD Jimmy Deeni- han (FG) who outlined local concerns about radon said such a low reaction was "dangerous and irresponsible" and he urged all householders in his constituency to carry out tests.
David Dawson of the RPII said it had carried out a survey in June of householders with high levels of radon. Under one-third of householders had carried out remedial measures and they cited cost as being one of the chief reasons. The second most important reason was the difficulty of getting advice. The survey found that the average cost of remediation was €1,600. Potentially 91,000 houses in Ireland had high radon levels, the forum heard.