Some 181 homes with high levels of the cancer-causing gas, radon, have been detected in Ireland in the past eight months, including four homes which had levels that were 10-22 times over the acceptable limit, the Radiological Protection Institute of Ireland (RPII) has said.

Radon, a naturally occurring radioactive gas present in all rocks and soils, is classified as a class A carcinogen by the International Agency for Research on Cancer. When it surfaces in the open air, it is quickly diluted to harmless concentrations. However, when it enters an enclosed space, such as a house, it can sometimes build up to high concentrations, leading to an 'unacceptable health risk'.

After smoking, long-term exposure to radon gas in the home is the greatest single cause of lung cancer in Ireland. The gas is linked to around 250 cancer deaths here every year.

According to the RPII, four homes were found to have very high radon levels of between 10 and 22 times the acceptable limit. Two of these houses were in Galway, one in Sligo and one in Wexford.

"The families living in these homes would have received a radiation dose equivalent to up to 15 chest x-rays every day," the RPII noted.

Altogether, almost 1,200 homeowners had their homes tested for radon over the last eight months, however Dr Ann McGarry, chief executive of the RPII, believes this figure is ‘very low'.

"Our research indicates that there are over 91,000 Irish homes with high levels of radon and, so far, only about 8,000 of these have been identified. Many families are unnecessarily being exposed to high levels of radon in their home and they just don't know it. All people have to do is take this simple test to see if their home contains radon and if so it's easily fixed," she said.

In addition to the four homes with particularly high radon levels, a further 25 homes were found to have radon levels that were up to 10 times above acceptable limits. These were located in Galway (8), Wexford (5), Kerry (4), Mayo (2), Sligo (2), Waterford (2), Tipperary (1) and Dublin (1).

Meanwhile Dr McGarry also pointed out that just one in four homeowners who did test and discover a high reading, ‘have taken action to reduce the high level of radon present'.

"That means three-quarters of homeowners are living with the knowledge that they are putting their family at risk when the problem can easily be fixed," she said.

In order to test for radon, a detector should be placed in a bedroom and a second detector should be placed in a living room for a three-month period. These detectors are available from the RPII and a number of private companies. They are sent and returned by post for analysis. Nobody needs to come to your home.

The cost of a measurement by the RPII is around €50.

If a moderate radon level is found, improving your home's indoor ventilation may cut this by up to half. The cost of this is low. If higher levels are found, installation of a fan assisted sump is the most common method of remediation. This can reduce radon levels by over 90%.

The sump can be installed in one day by a contractor, with little disruption to the home. The typical cost of this work is around €850, with annual running costs of around €100 depending on the size of fan installed.

An interactive map is available on the RPII website here to allow you to see if you are in a high radon area. Alternatively, more information is available on 1800 300 600.