Radon gas in buildings

Radon is a naturally occurring radioactive gas that results from the decay of uranium in rocks and soils. The gas is colourless, odourless and tasteless and can only be measured using special equipment.

In the open air, radon is harmless. But in an enclosed space such as a house, it may build up to an unacceptably high level. Radon from the ground enters buildings mainly through cracks in floors or gaps around pipes or cables.

The Environmental Protection Agency (EPA) is responsible for regulating, monitoring and advising on radiation matters. It assesses radon levels and identifies areas likely to be radon hotspots.

How is radon harmful?

When radon decays, it forms tiny radioactive particles which can stay suspended in the air. When you inhale these particles, they give a radiation dose that can damage your lungs.

Radon is a cause of lung cancer. Remaining exposed to high levels of radon in an enclosed area can increase your risk of lung cancer, particularly if you smoke. You can find out more about the effect of radon on your health.

Homes in some parts of the country are more likely to have a radon problem than others.

High radon areas

Some areas have high radon levels. You can use the EPA’s interactive radon map to check if you live in a high radon area. This is different to having your home tested for radon. Even if you are living in a low radon area on the map, your home may have high levels of radon when tested.

Radon testing

Every home has different amounts of radon so the EPA recommends that everyone has their home tested for radon. The EPA has a list of registered radon testing services.

Testing involves placing two small detection devices in the house for 3 months. This period allows for variations in radon levels, for example, due to changes in weather or ventilation. At the end of 3 months, you post the detectors back to the testing laboratory. The lab calculates the radon level in becquerels per cubic metre, expressed as Bq/m3. Read more about testing your home for radon.

If the radon level in your home is over the national reference level of 200 Bq/m3, the EPA recommends that you take action to reduce the level of radon in your home. This is called ‘radon remediation’.

The two main methods of radon remediation are to:

• Prevent radon entering your home from the ground underneath, for example, by making sure your home is fitted with a radon sump (a pipe that goes underneath the foundations of your home into the outdoor air).
• Remove the radon after it has entered your home, for example, by improving indoor ventilation or ventilation under your floors.

In either case, you should have your home re-tested after the work has been completed to ensure the radon level has dropped below 200 Bq/m3.

The EPA has a list of registered contractors for measuring radon in buildings. For further information about radon remediation, the EPA also has a householders guide to understanding radon remediation.

There is no current requirement for private landlords to test their rented homes for radon or to reduce radon levels if they are high. If you are a tenant and you are worried about the level of radon in your home, you should contact your landlord or Local Authority or Housing Association directly. For more information about radon and rented homes, visit the EPA website.

If your workplace is located in a high radon area on the EPA’s interactive radon workplace map, your employer must test your workplace for radon. You can read more about radon testing in the workplace on the EPA’s website.

The Department of Education arranges radon tests for schools. You can read more about radon testing in schools and find out how to check the radon levels of your school on the EPA's website.

• Read more about radon in the World Health Organisation’s factsheet
• For further information about radon, visit the EPA’s FAQ page about radon.
• For information about how you can reduce radon levels in your home, see the EPA’s webpage on Radon for Householders.
• Visit the EPA's website to learn more about the National Radon Control Strategy.