Several businesses in counties Kerry and Clare are facing prosecution for failing to test their premises for traces of the cancer-causing gas radon.
The State's nuclear watchdog - the Radiological Protection Institute of Ireland (RPII) - said it was taking action because the companies had refused to co-operate with instructions to carry out tests and report its findings.
The RPII said 60 employers in Ennis and Tralee were asked to take radon readings in May and June 2004 and that reminders were sent in October. Sixteen firms complied fully with the RPII, but the other businesses had either not complied or not complied fully.
Around a dozen prosecutions have been taken under the terms of the Radiological Protection Act 1991, and some of these are expected before the courts by the end of the year. Companies face fines of up to €1,270 and directors face imprisonment for up to 12 months under the terms of the Act.
An RPII spokeswoman said the employers involved could not be named but indicated they were both small and medium-sized companies.
"Radon is an issue that employers need to take action on. Last year the RPII directed 60 employers in Tralee and Ennis to measure radon. A number of these did not comply with the direction and prosecutions are pending," said RPII chief executive Dr Ann McGarry.
Radon is estimated to cause up to 200 cases of lung cancer each year - 10 to 15 per cent of all cases in Ireland. The naturally occurring radioactive gas passes through any cracks or gaps in floors and can reach high concentrations, posing a health risk to the occupants of the building.
The RPII estimate that up to 91,000 homes in the country have radon concentrations above the national reference level, with Co Clare one of the worst-affected counties.
The RPII national radon forum is being held today at the Meadowlands Hotel in Tralee, Co Kerry, where State agencies, architects, engineers, radon measurement and remediation companies and interested members of the public will discuss the issue.