ProTen Services feature in Housing Association Building & Maintenance

Step on the gas

Exposure to radon gas claims thousands of lives each year. Martin Freeman explains the risks, regulations and remedial methods, and considers the options for building managers.

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Radon, the naturally occurring radioactive gas, is fast becoming a primary concern for those involved in property management and maintenance. The gas is formed during the decay of uranium in the ground, and when it permeates the earth into open air, it is quickly diluted to harmless concentrations. If, however, it rises into a building, high concentrations can accumulate, posing a serious threat to the occupants.

When concentration of the gas is high, the radioactive decay products quickly attach themselves to particles in the air, which are then inhaled by the occupants. The particles can then be deposited in the lungs, where they continue to emit radiation. Each year in the UK approximately 2500 people die from lung cancer, developed as a direct result of exposure to radon. The gas accounts for the second greatest number of lung cancer cases in the UK, second only to smoking.

Given the serious consequences that could result should an individual be exposed to high levels of radon, legislation is in place to help eliminate such exposure.

The Housing Act 2004 introduced the Housing Health and Safety Rating System (HHSRS) to assess potential hazards in residential properties. Radon is covered under ‘Section 8: Radiation' and guidance states that the hazard should be assessed when the dwelling is in a designated radon Affected Area. Subsequent advice from the Health Protection Agency and the Health and Safety Executive is that high radon levels can be found in basements anywhere in the country, so it would also be advisable to assess the hazard if the property has a basement, regardless of its geographic location.

The only way to assess the presence and level of radon in a building is to test. A specialist detector should ideally be left in place for a three month period, before being sent to a laboratory for analysis. Radon levels fluctuate according to seasonal and occupational variation (e.g. amount of ventilation through opening windows) therefore a three month period is the recommended length of time to take such variations into account.

Radon concentration is measured in bequerels per cubic metre of air (bq/m³), and an Action Level of 200 bq/m³ has been set by the Government as the point at which remedial action should be taken in domestic properties. It is important to note that the Action Level does not represent a boundary between safety and danger, but simply a guideline as to the level at which the Government believes the hazard posed has become unacceptable and measures should be taken to reduce it. An individual who spends 8 hours per day in a building with a radon level of 200 bq/m³ will receive an annual radiation dose equivalent to that of more than 100 chest x-rays, and many believe the Action Level should be lowered.

The HHSRS categorises hazards into bands from A to J, with A being the most serious. Local authorities have a duty imposed upon them to ensure hazards falling in bands A-C are reduced. Radon levels in excess of the Action Level are classified as Band C or above (readings over 800 bq/m³ are Band A), and as such landlords must employ measures to reduce the levels or face enforcement proceedings from their local authority.

Although radon testing is only enforceable in properties situated in Affected Areas, it is an inexpensive and unobtrusive procedure that has the potential to prevent future cases of a life threatening disease. All landlords are therefore encouraged to take a proactive approach and test their properties, as Affected Area status is only based upon estimates, and does not provide a definitive answer as to whether any individual property will contain high levels of radon or not.

If high levels of radon are found in a property, there are various methods that can be used to lower the concentration and reduce the hazard. In the absence of a proper understanding of the science of radon, however, well-intentioned but uninformed measures can make the problem worse, rather than better.

Radon is drawn into buildings through a process called advection; the pressure inside a building is normally lower than outside, so gases from the soil are literally sucked in. Increasing ventilation, particularly through the use of extraction fans, can lower the pressure inside the building further, thus escalating the rate at which radon is drawn in and increasing its concentration.

ProTen Services Ltd, the nation's leading experts with over 20 years experience in radon testing and remediation, recently dealt with a domestic property, where a general contractor had originally been employed to reduce the radon level. ProTen Services conducted a radon test, which revealed the property contained radon levels in excess of 2100 bq/m³. The non-specialist contractor had previously installed a ventilation system, which ProTen suspected to be exacerbating the problem. When the system was switched off, the radon level halved to 1100 bq/m³. ProTen then designed a specialist positive pressure system to dispel the gas currently trapped inside the property and increase the pressure of the building, preventing any further gas infiltration. A post-remediation radon test revealed the level of radon in the property had been reduced to 63 bq/m³.

This highlights not only the need to use a specialist contractor, but also the need for testing after measures have been taken, as without this, it will be impossible to know if the actions have been effective, or indeed detrimental.

When designed by a specialist, a radon mitigation system can also bring secondary benefits to a property, such as improved air quality, condensation reduction and cost-effective heat exchange.

Radon mitigation is a specialist and potentially life-saving area of construction and building management, where training and sophisticated accuracy are imperative to its success. A specialist contractor should always be employed to tackle the issue, to ensure the hazard is effectively minimised.