Health Specialists

image of source of radiation

Please note that from early 2019 the Reference Level for radon in workplaces reduced from 400 Bq/m3 to 300 Bq/m3.  This reduction is on foot of regulations to implement Council Directive 2013/59/Euratom (Radiological Protection Act 1991 (Ionising Radiation) Regulations of 2019). Therefore if the measured radon concentration in a workplace is greater than 300 Bq/m3 remedial action is required to reduce those levels to below 300 Bq/m3.

The World Health Organisation has categorised radon as a carcinogen, in the same group as asbestos and tobacco smoke. In Ireland, approximately 300 cases of lung cancer each year are linked to exposure to radon. There is no scientific evidence linking radon with any other types of respiratory illnesses or other cancers.

The greatest health risk from radiation in Ireland is caused by radon. It accounts for 55 per cent of the total radiation dose received by the Irish population.

Radon is a radioactive gas.  It has no taste, colour or smell.  It is formed in the ground by the radioactive decay of uranium which is present in all rocks and soils. You cannot see it, smell it or taste it.  It can only be measured with special detectors.

Radon can enter a building from the ground through small cracks in floors and through gaps around pipes or cables. Buildings in some parts of the country are more likely to have a radon problem. These parts of the country are called High Radon Areas. You can check our interactive map to see whether a building is in a High Radon Area. Outside radon is diluted to very low levels.

The acceptable level, or Reference Level, for homes and schools in Ireland is 200 becquerel per cubic metre (Bq/m3). For workplaces, the Reference Level is 300 Bq/m3

Health Risks

image of radon lungs Over a long period of time, exposure to radon can increase your risk of developing lung cancer. Radon produces tiny radioactive particles. When they are inhaled these particles can be deposited in the airways and result in a radiation dose to your lungs. There is a synergistic effect between radon and tobacco smoke. This means that smokers are at much greater risk of developing radon related lung cancer than non-smokers. 

The risk of developing radon related lung cancer

In Ireland, it is estimated that a lifetime exposure to radon in the home at the Reference Level of 200 Bq/m3 carries an average risk of about 1 in 50 of contracting lung cancer.

The risk is much lower for non-smokers at about 1 in 700 and far greater for active smokers at about 1 in 30.

  • Non Smoker, little radon exposure - LEAST RISK
  • Non Smoker, some radon exposure - SOME RISK
  • Smoker, little radon exposure - INCREASED RISK
  • Smoker with radon exposure - GREATEST RISK

Radon is a risk factor for lung damage due to its direct local effect on the lung. Cigarettes also have direct effects on the lung. There is no way of telling whether an individual lung cancer case is linked to radon or smoking.

There is no test to measure exposure to radon

Radon damage to human tissues is not detectable by routine medical testing. Also, there is no effective health screening test for lung cancer. Technologies such as CT screening also involve radiation exposure and are not indicated in this situation.

Learn More

To find out more read our radon and your health leaflet

What Can I Do?

As a health professional, there are two actions you can take - explain the risks and encourage patients to take action to reduce the risk of developing radon related lung cancer:

  1. If your patient smokes encourage him/ her to quit smoking now. The HSE QUIT service offers support to smokers via phone, text, live chat, Facebook and through clinics and support groups.
  2. If your patient’s radon level is above 200 Bq/m3. Work to reduce radon levels should be carried out as soon as is practical and should reduce radon levels to significantly less than 200 Bq/m3.

These actions will immediately reduce the risk of developing radon related lung cancer.


The World Health Organisation provides useful information about radon and health

Other publications that may be of interest include:

Testing for Radon

The only way to know if radon is a problem in a home is by having a radon test carried out.

Please watch our video to see how easy it is to test a home for radon.

A radon test is carried out by placing two small detectors, about the size of an air freshener, in a home for three months. One detector is placed in a bedroom the other in a living room - the places most occupied by the family. After three months, when the detectors are posted back to the laboratory, they are analysed to see how much radon they have been exposed to in the home.

image of radon detector The results of the radon test will then be posted to the homeowner. If the results are high, advice on what to do next will also be included.

Buying a radon test 

The EPA provides a list of registered radon testing services.

Retesting a home

When a home has tested below the reference level of 200 Bq/m3 there is no need to re-test unless major refurbishment work has been carried out on the house. For example fitting new windows or building an extension and other such work that could in theory open up new entry routes for radon or prevent radon escaping from your house. It is also recommended that a home is retested when there is a change in occupancy.

The EPA recommends that homes that have tested above the reference level of 200 Bq/m3 and then carried out remediation work should be retested every 5 years to ensure the remedial work remains effective.

Where results are above the Reference Level

The EPA uses a graded approach to respond to reported radon concentrations in homes and workplaces above the Reference Level. This approach is summarised as follows:






200 - 800 300 to 2,600   Write to customer recommending remedial action
800 to 2,000 2,600 to 6,500   As above and telephone customer
2,000 to 4,000 6,500 to 13,000   As above and issue public statement
Above 4,000 Above 13,000

  As above and take local public awareness action

  Engage with other statutory authorities and local authority

Reducing High Levels

If the results from your radon test show that the radon levels in your home are high there are a number of simple ways that you can reduce these levels.

Please watch our video to see how easy it is to reduce radon levels in your home.

The best way to reduce radon depends on the levels in your home and the building type. Here is a guide to the methods most commonly used:

image of vents Improving indoor ventilation

One of the simplest ways to dilute moderate levels of radon is to increase the indoor ventillation by installing wall vents or window trickle vents. This can reduce radon levels in a home by up to 50%. It is important that increased ventilation is installed at ground level only as additional ventilation on upper floors may increase the flow of radon from the ground into your home. This work usually costs in the region of a few hundred euro.‌ 

Improving under-floor ventilation (for homes with suspended floors)

If a home has a suspended floor you can also reduce the amount of radon entering the building by increasing the sub-floor ventilation. Clearing or replacing existing sub-floor vents or installing additional vents or airbricks will increase the flow of air below the floor and so reduce the amount of radon entering a home. This work usually costs in the region of a few hundred euro.

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image of passive sump Installing a passive sump

For radon levels up to 400 Bq/m3, a passive sump can reduce radon levels by up to 50%. A passive sump is a sump system that works without the action of a fan. Instead, wind action over the top of the sump-pipe (which often is fitted with a rotating vane or ventilator) draws radon up through the sump system.

Installing an active radon sump

The most effective and most commonly used way of reducing the flow of radon into a home is by installing an active radon sump. A radon sump is a cavity about the size of a bucket immediately under the floor slab that is linked by pipe work to the outside. The radon rich air coming from the ground is drawn out from under the floor slab by a small electric fan in the pipline and vented to outside before it is drawn into your home. This can reduce radon levels in your home by about 90% and sometimes up to 99%. An active radon sump can usually be installed in one day and all the work is carried out from outside the home.The work typically costs about €925, but this can range from €400 to €1500, depending on the complexity of the work. The annual running cost of the fan depends on the power of the fan used. The running costs range from about €30 using a 14 watt fan to about €150 for a 70 watt fan. Typically an active sump can reduce radon levels by about 90% but this may range from 60% to 99%.

image of active sump added and outlet at eaves  

Getting the work done

The EPA provides a list of registered contractors who will be able to advise you about the most suitable solution for your home.

Discuss the following issues with the contractor: testing your home following remediation work; fan maintenance (for active sumps); costs of running fans (for active sumps) and retesting following significant building work on the home.

  • It is important to have your home re-tested after the work has been completed, to ensure that it has reduced the radon levels in your home.

To find out more read our understanding radon remediation booklet

The EPA provides a free post-remediation service to homeowners. Please contact us to avail of this.

Normally remediation is successful at the first attempt. However, sometimes more work is needed to reduce the radon levels to below 200 Bq/m3. It is a good idea to agree with the contractor what steps may be taken if the radon levels remain high.

There is no absolute certainty that radon will be reduced to below 200 Bq/m3 even following a number of remediation attempts. While this rarely happens, it is important to note that any significant reduction in radon levels will reduce your risk of lung cancer even if the levels are not reduced below 200 Bq/m3.

image of active sump with fan at ground level

Maintenance of remediation systems

For active sump systems it is important to discuss the choice of fan with the contractor. It is also important to ensure that passive ventilation systems remain clear from debris.

Radon Prevention

image of standby sump If your home was built after 1st July 1998, the building regulations require that it is fitted with a standby radon sump. This is simple pipe work that extends from under the foundations into the outdoor air. If high radon levels are measured, the standby sump can be activated by adding a fan. It should be noted that a standby sump that has not been activated by adding a fan does not reduce radon levels in your home.

For houses built in High Radon Areas the installation of a radon barrier as well as a standby sump is required. The installation of these protective measures is not a guarantee that radon levels will be below 200 Bq/m3. You should therefore have a radon test carried out within the first year of moving into your new home.

image of radon membrane