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Radon: the invisible threat

Radon is the major radiological issue in Ireland and represents more than half of all exposure to radiation here.

The main danger from high levels of radon exposure is lung cancer. It has been estimated that 250 lung cancers are linked to radon in Ireland every year.

The risk of developing lung cancer is much higher in smokers than non-smokers. According to the World Health Organisation (WHO), smokers are 25 times more at risk from radon than non-smokers.

As Ireland’s radon level is well above the EU and worldwide averages, a National Radon Control Strategy was launched in 2014 in a bid to reduce radon levels and raise awareness of the problem.

But despite the risks, complacency among the public about the issue, particularly homeowners where high radon levels are detected, remains a significant challenge.

What is radon?

Radon is measured in becquerels per cubic metre (Bq/m3) and is a carcinogen categorised by the WHO in the same group as asbestos and tobacco smoke.

It is a naturally-occurring radioactive gas, has no taste or smell and is invisible. Radon is formed in the ground through the radioactive decay of uranium, which is present in all rocks and soil. It can also be present in groundwater.

According to the Environmental Protection Agency (EPA), radon accounts for 55 per cent of all radiation exposure in Ireland.

Remedial action should be taken at a person’s home if their radon level is above 200Bq/m3, the EPA recommends. In workplaces, action is recommended at levels above 400Bq/m3.

According to Senior Scientist with the EPA, Ms Stephanie Long, a WHO survey of 31 countries in 2009 showed Ireland had the eighth-highest radon level.

The radon average in Ireland is 77Bq/m3, which has decreased from an average of 89Bq/m3 due to changes in building regulations enforcing the use of radon barriers and sumps in new buildings in high-radon areas since 1998.

Ms Long outlined that the UK has an average level of 20Bq/m3 and the EU average is 59Bq/m3. The worldwide average is 39Bq/m3.

Radon levels in countries vary due to the geology of the country and rock types, Ms Long explained.

The figure of 89Bq/m3 was derived from a survey conducted in the 1990s of radon measurements in 11,000 homes, through which the radon risk map of Ireland published on the EPA’s website was generated. 

This map is based on a 10km grid but the Tellus Programme is working on producing a new, more detailed geological radon map based on a 1km grid.

The Tellus Programme is managed by the Geological Survey of Ireland (GSI) and is working alongside the EPA to improve understanding of the distribution of radon gas to update maps.

To date, the EPA has tested 60,000 homes in Ireland for radon and provides radon test kits by post for homeowners, along with four other registered companies listed on the EPA website.

Health risks

HSE Consultant in Public Health Medicine Dr Ina Kelly told the Medical Independent (MI) that for every 100Bq/m3 an individual is exposed to, their risk of developing lung cancer is raised by 16 per cent.

The risk of developing lung cancer from exposure to radon depends on how much radon the person has been exposed to, how long they have been exposed to this level of radon and whether or not the person is a smoker.

Radon is breathed into the lungs and energy from radioactive particles can damage DNA and increase the risk of lung cancer.  

If a person is exposed to radon for a long time, traces of radon are not found in the lungs, stated Dr Kelly.

“I don’t think it’s really possible to determine the cause of a person’s lung cancer in a non-smoker except through exposure history,” Dr Kelly said. 

“But if you lived in a house with high radon and didn’t smoke, didn’t work with asbestos and weren’t exposed to environmental tobacco smoke, you’d have to say it was likely to be radon.”

According to the National Cancer Registry Ireland (NCRI), some 2,279 cases of lung cancer per year were diagnosed between 2011 and 2013.

Lung cancer was the leading cause of cancer death in both sexes, comprising 18 per cent of cancer deaths in women and 22 per cent of cancer deaths in men during the same time period. 

Few studies have been conducted on lung cancer and radon in Ireland. However, a small study was undertaken by University Hospital Galway and the Radiological Protection Institute of Ireland (which merged with the EPA in 2014) looking at radon exposure levels among lung cancer patients.

Titled Household Radon Exposure in Patients Attending a Rapid Access Lung Cancer Clinic, some 42 patients attending the clinic completed the study, which was published in 2014.

It found there was a poor understanding of radon risk, despite the fact that 21 per cent of patients had high radon exposure levels (above 200Bq/m3).

The EPA and HSE are encouraging health specialists to explain the risks to patients and encourage them to take action to reduce their risk of developing radon-related lung cancer.


A report from the HSE National Tobacco Control Office in 2014 showed that smoking rates in Ireland fell from 21.5 per cent in 2013 to 19.5 per cent in 2014.

In 2003 some 28 per cent of the population smoked, therefore smoking rates have fallen by almost 10 per cent in 10 years.

Dr Kelly said that of the two big risks for lung cancer (smoking and radon), smoking is by far the biggest and she urged health professionals to continue to encourage patients to quit smoking.

“Of the people whose cancer is probably attributable to radon, most of them will still be smokers but they may not have gotten lung cancer without having radon exposure as well,” noted Dr Kelly.

“We know that smokers are about 25 times more likely to develop lung cancer [due to radon gas] than if you don’t smoke.

“Lung cancer risk is related to prolonged exposure and there is a relatively long latency. Radon and smoking exposure — when those things reduce, you’re not going to see the effect of that for some years, probably five years’ minimum but more likely 15 years before you would see a difference.”

Dr Kelly explained that the risk of developing lung cancer from smoking is independent of radon exposure but that the two risks are on the same pathway.

Tobacco damages the lining of the respiratory system, making it more vulnerable to inhaled toxins.

As smoking rates and the average radon level have fallen in Ireland in recent years, it is hoped that this may lead to a fall in radon-related lung cancers in the future.

According to Ms Long, the 250 radon-related lung cancers per year figure is based on the average radon level of 89Bq/m3, which recently dropped to 77Bq/m3 following another survey by the EPA.

Later this year, the EPA plans to release new data updating the number of radon-related lung cancers in Ireland.

The data relates to a population-weighted average survey taking account of where the main population centres are and will allow the EPA to calculate the current number of radon-related lung cancers.

“Hopefully it will come down. The number of lung cancers is very much complicated by smoking rates because smoking predominates the risk and smoking rates have fallen,” Ms Long noted.

“What we’re hoping to see is that there will have been a reduction in radon-related lung cancers.”

The data currently being collated is based on research undertaken in 700 homes, with the assistance of University College Dublin statistician Dr Patrick Murphy.


Some 11 actions contained within the National Radon Control Strategy 2014-2018 are now complete.

The strategy has 31 actions in total and its ‘Year 3’ report is due to be published in May, according to a Department of Communications, Climate Action and Environment spokesperson.

Among actions completed within the last 12 months are the inclusion of three questions relating to radon in the conveyancing process; the completion of a training course for site staff on radon prevention; and the roll-out of a training course on radon remediation for local authorities, public bodies and radon contractors.

Other actions completed include the establishment of a registration scheme for radon remediation contractors; establishment of a registration scheme for radon measurement services; and the completion of the multi-annual programme of local radon awareness campaigns in 12 priority counties.

The website was also launched in October. 

The Department spokesperson stated that “it is critical that a scheme offering financial assistance to home-owners to address radon is established to ensure the effectiveness of the NRCS [National Radon Control Strategy].

“One of the recommended actions of the NRCS is to explore possible financial incentives which might encourage householder action on radon. This remains a key challenge for Year 4 of the NRCS and the Department is currently focusing on examining the feasibility of providing such financial incentives. A strategy to address radon will be a regulatory requirement from 2018.”

The cost of fixing a home with a radon problem is about €900, according to Ms Long. 

She added that Ireland’s first annual National Radon Week would commence in November, to coincide with European Radon Day on 7 November to replace local campaigns.

Ms Long stressed the importance of awareness campaigns in informing the public about health risks. She said complacency remains a challenge.

“There is certainly a lot of awareness and people are concerned about it but often this doesn’t translate into action,” Ms Long said.

“When people test and know their house has a problem, only one-in-four will go on to reduce radon levels. That always perplexes us.”

But, as she explained, this behaviour is reflected in other countries and is simply “human nature”.

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