Radon
Radon is a natural radioactive gas with no taste, smell or colour. Radon and the radioactive elements formed by its decay can be inhaled and enter the lungs. Inside the lungs, these elements continue to decay and emit radiation; internally alpha particles pose the greatest health risk. Ionising radiation causes cell damage which can lead to lung cancer. Radon is now recognised to be the second largest cause of lung cancer in the UK after smoking. Lung cancer is also the biggest cause of cancer related death in the UK with only 5% of detected lung cancers being successfully treated.
Radon is measured in units of becquerels per cubic metre, Bq/m3 (i.e. concentration of radioactivity in air). Radon contributes by far the largest component of background radiation dose received by the UK population and significant exposures are possible in workplaces. Studies on occupational groups with known high exposure to radon show a significantly increased risk of lung cancer. It is also known that the risk of lung cancer from radon is approximately 25 times higher for cigarette smokers than for non-smokers. |  |
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The Northern Ireland Environment Agency have produced a radon probability map at a resolution of 1 square kilometre. The highest radon areas have been defined by Government as radon Affected Areas. For more detailed information see http://www.doeni.gov.uk/niea/
This indicative atlas, shown opposite, was published in 2009. The darker the colour the greater the likelihood of significant radon levels within buildings in that area. Although the indicative atlas is produced from measurements in homes, the maps indicate the likely extent of the local radon hazard in all buildings. The information in this atlas is therefore relevant to employers in assessing workplace risks.
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High radon levels are associated with underground workplaces/rooms and those incorporating water and have also be linked with other utilities and air conditioning in which the pressure is unbalanced.
Under the Health and Safety at Work (NI) Order 1978, employers must, so far as is reasonably practicable, ensure the health and safety of employees and others who have access to their work environment. The Management of Health and Safety at Work Regulations (NI) 2000 require the assessment of health and safety risks. Employers may choose to request a radon risk report for their postcode area from www.ukradon.org (a small fee is charged). The report estimates the probability that their property is above the Action Level for radon.
Assessment of radon risks should include radon measurements in the following circumstances:
All workplaces located in Radon Affected Areas
For the vast majority of above ground workplaces the risk assessment should include radon measurements in appropriate ground floor rooms where the building is located in a radon Affected Area. This includes buildings constructed after 2000 with protective measures installed during construction.
All below ground workplaces
For occupied below ground workplaces (for example rooms occupied greater than an average of an hour per week/ 52 hours per year), or those containing an open water source, the risk assessment should include radon measurements. This applies to all below ground workplaces in the UK, irrespective of the above ground Affected Area status.
Remedial action
Continue monitoring until remedial action is complete (generally within six months)
Review
Conduct periodic testing and routine checks
The HSE and Local Authorities are responsible for enforcing these regulations in particular types of workplace.
Radon surveys should be conducted for the above highlighted circumstances. The surveys are inexpensive and are carried out by leaving small plastic passive detectors in rooms of interest. The Health Protection Agency (HPA) website contains up-to-date details of validated laboratories capable of supplying detectors for undertaking radon measurements. Delivery and return of the detectors is normally by post.
Measurements are usually made over a period of three months and the worst-case winter levels estimated using seasonal correction factors.
Between two and ten monitors are often enough for most buildings. Monitors should be placed on the ground floor in rooms which are routinely occupied. A good rule of thumb is one monitor for each 100m2 of floor space. Basements that are routinely occupied should also be measured. |  |
The Action Level of 200 Bq/m3 identifies radon levels above which action to reduce radon in homes is most urgent, but it is important that substantial reductions are made - not just aiming to get under the Action Level. The health risk from radon is considered to be proportional to the level of long term exposure, with no safe/unsafe threshold. Health risks below the Action Level are smaller but not zero.
The UK has also adopted a Target Level of 100 Bq/m3. The Target Level is being promoted in homes. It is also being promoted in schools and other premises where occupancy by members of the public exceeds 2,000 hours per year. This Target Level is in addition to the current level of 400 Bq/m3 at which level action should be taken to reduce radon concentrations.
The Ionising Radiations Regulations (NI) 2000 (IRR2000) apply where radon is present above the defined level of 400 Bq/m3 and employers are required to take action to restrict resulting exposures. Where the workplace measurements show radon levels below 400 Bq/m3, as is the case for the majority of employers, then the only further required action is to decide when the risk assessment will be reviewed.
(This figure of 400 Bq/m3 is comparable with the Action Level for homes, taking into account that most people spend much more time in their home than at work.) Reducing the radon levels to below 100 Bq/m3 is the ideal outcome for remediation works in existing buildings and protective measures in new buildings. If the result of a radon assessment is above the Target Level of 100 Bq/m3 further action to reduce the level should be seriously considered.
For occupied areas with levels above 400 Bq/m3, the employer is obliged to take action.
- The relevant enforcement authority should be notified of the presence of radon in workplaces at concentrations above 400Bq/m3 (or the Target Level where this applies).
- A Radiation Protection Adviser with radon experience should normally be consulted about how to best manage radon exposures.
- However if the employer plans to immediately remove the radon so that the IRR2000 do not apply, a specialist radon removal (remediation) contractor can be consulted in the first instance. The specialist will be able to advise on the most cost effective engineered means of reducing radon gas to the lowest reasonably practical levels.
- It is usually appropriate to continue monitoring in these areas at least until the reduction measures have been put in place and monitored to ensure their effectiveness.
- Employees should be informed.
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The chart opposite shows the combinations of radon level and working times that would require formal protection measures. As levels increase above 400Bq/m3, the protection measures become more onerous. |
The Building Research Establishment (BRE) website and BRE Report 293 describes radon solutions. Such measures include improved under floor and indoor ventilation in the area, sealing large gaps in floors and walls in contact with the ground, positive pressure ventilation of occupied areas, and installation of radon sumps and extraction pipework.
If it is necessary to reduce radon levels by engineered means, the employer should ensure that the radon levels in the area are re-measured immediately after installation in order to verify its effectiveness
As with all health and safety risk assessments, their applicability should be kept under review. The following guidelines are suggested:
| Radon level Bq/m3 |
Frequency of re-measurement |
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Significantly less than 400
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Once every 10 years
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Just below 400
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More frequently than every 10 years
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Above 400
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During remediation, immediately after remediation and significantly more frequently than every 10 years
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If engineered systems are fitted to reduce levels then procedures must be in place to ensure that they remain mechanically operational and kept switched on.
In Radon Affected Areas employees could also be receiving significant exposure at home. Employers are strongly encouraged to recommend home testing to their employees who live in the radon Affected Area.
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Additional information on Radon can also be found from HSENI's Radon Information Booklet
Further information on Radon may be obtained from the following websites:
www.ukradon.co.uk
www.hse.gov.uk/
www.hpa.org.uk
www.doeni.gov.uk/niea
www.bre.co.uk/radon
