Please note that from early 2018 the Reference Level for radon in workplaces will reduce from 400 Bq/m3 to 300 Bq/m3.  This reduction is on foot of regulations to implement Council Directive 2013/59/Euratom. Therefore if the measured radon concentration in a workplace is greater than 300 Bq/m3 you should consider taking remedial action to reduce those levels.

The acceptable level, or Reference Level, for workplaces, is 400 Bq/m3.

The World Health Organisation has categorised radon as a carcinogen, in the same group as asbestos and tobacco smoke. In Ireland, up to 250 cases of lung cancer each year are linked to exposure to radon. 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.There is no scientific evidence linking radon with any other types of respiratory illnesses or other cancers.

Radon is a naturally occurring 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.

Outside radon is diluted to very low levels. Radon can enter a workplace from the ground through small cracks in floors and through gaps around pipes or cables. Workplaces 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 your workplace is in a High Radon Area. The only way to know how much radon is in your workplace is to take the radon test.

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 lung cancer. 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

Your risk of contracting lung cancer from exposure to radon depends on:

  • how much radon you have been exposed to
  • how long you have been exposed to this level of radon
  • whether or not you are a smoker (smokers are at 25 times more risk from radon than non-smokers)

Find out more read our health leaflet.

My Responsibility

Exposure to natural radiation sources in the workplace is governed by the Radiological Protection Act, 1991 (Ionising Radiation) Order, 2000 (Statutory Instrument 125 of 2000). This legislation specifies the national Reference Level for radon in workplaces of 400 becquerels per cubic metre (Bq/m3) measured over a 3 month period. When the national Reference Level is exceeded, employers must take measures to protect the health of workers usually by reducing the radon levels.

Under the Safety, Health and Welfare at Work Act 2005, every employer has a general duty to identify hazards in the workplace to minimise them. The Health and Safety Authority (HSA) has stated that all workplaces at ground floor or basement level in High Radon Areas must be tested for radon.

Which workplaces are most at risk?

Two categories of workplace are more likely to have high radon levels:

  1. Indoor workplaces located in High Radon Areas. The EPA recommends that all employers test for radon since workplaces in low risk areas test above the Reference Level of 400 Bq/m3. To help employers plan a radon survey of their workplace, the EPA has produced a booklet Planning Radon Surveys in Workplaces – Guidance Notes.
  2. All underground workplaces, such as mines and caves. Radon has long been recognised as a hazard in this category of workplace. Employers with staff working underground are required to take measures to protect their employees. To assist such employers, the EPA has produced a booklet Radon in Underground Workplaces- Guidance Notes for Employers which provides advice on protecting underground workers.

Because it is impossible to predict exactly where high radon levels will be found, it is recommended that every workplace should have a radon test carried out, even those located outside a High Radon Area.

Outdoor workplaces such as agriculture, transport, construction and fishing are unaffected by high levels of radon, and do not need to be measured.

Testing for Radon

A workplace is tested by placing one small detector, about the size of a matchbox, in each occupied room on the ground floor or in the basement. Only those workplaces with an occupancy of more than 100 hours per year need be measured.

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. It is a legal requirement that radon testing in the workplace must be carried out for at least three months. A report with the radon level in each room tested will then be sent to you. More details about testing your workplace for radon are available in our booklet.

image of radon detector For underground workplaces such as caves and mines, the EPA has produced specific guidance.

Indoor radon levels vary greatly from one building to another and the measurement from a neighbouring building is no indication of the level of radon in your workplace.

Buying a radon test

A number of companies provide a radon testing service.

Next steps

If your workplace has radon levels below the national Reference Level (400 Bq/m3), no further action is required. If your workplace has radon levels above 400 Bq/m3:


  • The EPA Office of Radiological Protection must be notified immediately of the results (if a radon testing service other than the EPA has carried out the test).
  • The preferred and simplest course of action is to carry out remedial work to reduce the radon level to below 400 Bq/m3.
  • Where radon levels exceed 800 Bq/m3, remedial work must be carried out as soon as is practicable, but no later than six months from the date of the test.
  • Alternatively, where radon levels are between 400-800 Bq/m3, the employer may carry out an evaluation to decide whether remediation is justified.


Reducing High Levels

If the results from your radon test show that the radon levels in your workplace are above 400 Bq/m3 there are a number of simple ways that you can reduce these levels. The best method to reduce radon depends on the levels found in your workplace and the building type. An EPA registered remediation contractor will advise you about the best solution for your building. Following remediation, it is important to re-test each of the rooms that tested above 400 Bq/m3 to ensure that this work has been successful in reducing radon in each of these rooms to below this Reference Level.

Normally remediation is successful at the first attempt. However, sometimes more work is needed to reduce the radon levels to below 400 Bq/m3. It is a good idea to agree with your contractor what steps may be taken if the radon levels remain high following remediation.

However, there is no absolute certainty that radon will be reduced to below 400 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 the risk of lung cancer even if the levels are not reduced below 400 Bq/m3. For more information about what you can do when high radon levels are measured in your workplace read our guidance note

Our video will provide some guidance on how to fix a home or other building with high radon levels.

image of vents In some cases, more than one solution will be needed to reduce radon to below 400 Bq/m3. The remediation methods most commonly used are summarised here:

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 the home. This work usually costs in the region of a few hundred euro.‌ 

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

If a workplace 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 your workplace. This work usually costs in the region of a few hundred euro.

image of subfloor vent  














image of subfloor vent active



















Installing a passive sump

image of 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 your workplace 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 pipeline and vented to outside before it is drawn into your home. An active radon sump can usually be installed in one day and all the work is carried out from outside your workplace. 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 recommends that remediation work is carried out an EPA registered contractor who will be able to advise you about the most suitable solution for your building.

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 building.

To find out more read our booklet on remediation.












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.

Following remediation

The EPA recommends that workplaces that have tested above 400 Bq/m3 should be retested every 5 years.All remediated areas must be retested to ensure the work has successfully reduced radon to below 400 Bq/m3. The EPA must be informed that the remedial work has been finished, within six months of completion. The remediation systems must be properly maintained to ensure they remain effective at minimising the radon build-up within the workplace.

Radon Prevention

image of standby sump If your workplace 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 workplace.‌ 

For workplaces 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 the workplace Reference Level of 400 Bq/m3. The EPA therefore recommends that all workplaces are tested for radon.

image of radon membrane


Our Guidance Notes provide further information about radon in workplaces:

Radon in Workplaces Booklet
Planning Radon Surveys in Workplaces - Guidance Notes
Radon in Underground Workplaces - Guidance Notes
The Need for Remediation in Workplaces - Guidance Notes


Radon tests

Prices charged by measurement services may vary from €40 to €60.

Remediation costs

There is no grant available to assist with the cost of radon remediation in workplaces. Some radon reduction techniques are more expensive than others. Typically the cost to retrofit a radon sump is about €925 (ranging from €400-€1500). Other, less expensive options are available, for example, improving the ventilation in your workplace by installing extra wall vents. This type of work usually costs in the region of a few hundred euro.

Radon Services

Registered Radon Remediation Services

Under the National Radon Control Strategy a registration scheme for radon remediation services has been developed.  Registered remediation contractors have met a number of requirements including attendance at a training course on remediation, followed by a successful assessment, adherence to a code of practice, tax compliance, appropriate insurance, etc. Further details of this registration scheme are available in the Radon Remediation Registration Form.

Assuring the quality of work provided by radon testing services

To ensure that radon testing services offer accurate and consistent results the National Radon Control Strategy recommended that a registration scheme be developed.

The EPA is currently rolling out this registration scheme, which requires radon testing services to participate in proficiency testing, show compliance with criteria such as testing procedures, quality standards, the standard of information provided to customers and legal compliance matters. Further details are available in this guidance document and registration form.

The registration scheme will be finalised in early 2017 and the list of registered testing companies available on this website.

How do I choose a testing company now?

The EPA provides an accredited radon testing service. The EPA also provides a list of other radon testing companies.

This list is provided for information only. At present, the EPA does not approve, authorise or otherwise recommend the services provided by other radon testing companies.

To determine whether the radon levels in a workplace exceed the Reference Level the Regulations require that the test should be carried out over a minimum period of three months. For homes a minimum three month measurement is also recommended by the EPA. For these measurements, the use of passive detectors is generally the most cost effective and the most straightforward approach.