IT'S a colourless, odourless radioactive gas released into the air by decaying uranium, which is found in rocks and soils. In the open air radon is diluted to harmless levels. In enclosed spaces it can be a health hazard.
It is nine times heavier than air so it is not normally a problem in the upper stories of high rise buildings.
Radon seeps into houses through cracks in floors or gaps around pipes or cables. Building materials and domestic water and gas supplies can also produce radon. Home heating and the effect of wind reduce the pressure in a house so radon gas is sucked in.
Why is it dangerous?
WHEN radon enters a house it is broken down into radioactive particles. If they are inhaled the particles can attach themselves to lung tissue, giving a radiation dose which could lead to lung cancer.
How big a risk is it?
RADON is believed to be the cause of more than half the radiation dose received by the average person in Ireland. The rest of our dose comes from natural radioactivity of soils, building materials and foodstuffs and from medical exposures (such as X rays).
Most of us don't need to worry about radon. But for a small percentage of people long term exposure to radon in their homes can be a significant health risk.
The Radiological Protection Institute of Ireland (RPII) estimates that if you are exposed to radon at moderate levels you have a one in 50 chance of contracting fatal lung cancer. That is twice the risk of dying in a road accident. Smoking increases that risk.
How do I know if my house is affected?
THE experts recommend measuring radon over three months, using a small testing device. Radon is measured in becquerels (a unit of radioactivity) per cubic metre of air (Bq/m3).
The RPII will carry out a radon test for £15. The institute is at 3 Clonskeagh Square, Clonskeagh Road, Dublin 14. Phone 01 2697766
The maximum acceptable level, known as the reference level, is 200 Bq/m3. The highest concentration found in a house in Ireland was more than 20 times this reference level.
What can I do to get rid of radon?
SEAL cracks in ground floors and adjoining walls, depressurise the under floor space with passive or fan assisted pumps which draw soil gas away from the building; adjust the air pressure inside a building and improve ventilation. The Building Research Establishment (BRE) recommends a fan assisted sump as the most effective anti radon measure.
The Department of the Environment has produced a guide, called Radon in Buildings. It's available from ENFO, the Environmental Information Service, 17 St Andrew's Street, Dublin 2, for £5.