Measuring radon

How do I obtain radon measurements?

There are a number of reliable detection methods available for assessing the average radon levels within your home. Any of these can determine whether or not there may be a risk worthy of further study or remedial work (i.e. work to reduce radon gas levels).

From the scientific point of view, the longer the testing procedure the more accurate the results may be. The preferred method is to test over a period of typically 3 months, however methods of detection have been developed that give accurate readings of radon in a period as short as 7- 10 days usually essential in house conveyancing operations. They are a popular technique in both the USA and the UK.

Caution:- The Council is aware that some organisations are operating in the UK offering “Instant” radon sampling measurements using portable measuring equipment. Because radon levels can and do vary considerably throughout the day, any measurements of less than 4 days should be avoided.

As with any measurement technique it is the interpretation of results that are important. Such interpretation recognises difficulties in sampling, house construction, ventilation and human activities, as well as seasonal changes. Given proper interpretation the short-term tests are equally acceptable in deciding whether there may be a need for further detection or remedial work. A number of reliable and fully experienced companies offer a range of long term detection methods and several offer the 7-10 day tests as well.

What do I do if high levels are recorded?

If you find that you have levels above the current ” Action Level” (i.e. 200 Bq m-3 [Becquerels per cubic metre] for the home or 400 Bq m-3  in the workplace), you need to consider the wisdom of having remedial work carried out to reduce radon gas levels. The Becquerel referred to is the unit of measurement normally used by the industry. It is worth noting that the World Health Organisation have recommended recently that radon action levels be reduced to 100 Bq m-3. 


How can radon levels be reduced?

As the air pressure inside the building is the main factor affecting the entry of radon gas, techniques which alter this pressure differential are the most successful ways of remediating buildings with high radon levels.

Two such techniques are the use of specialist positive pressure units and retro-fitting a radon sump beneath the building.

It must be recognised that radon mitigation is a specialist and sophisticated service, where an understanding of the science of radon movement is required. Some techniques, such as the use of extract fans to increase ventilation can in fact exacerbate the problem and cause greater volumes of the gas to be drawn into the property. It would therefore be unwise to place such responsibility in the hands of an unskilled contractor.

Reducing radon levels in properties with basements is particularly difficult, due to the large area of low pressure created by the basement. A system should be used that will not only reduce radon levels in the basement but prevent the gas from being displaced into the ground-floor accommodation. Waterproofing to the British Standard BS 8102 must also be achieved if the basement is to be useable.

Given the nature of radon entry into buildings, radon should be viewed as something that needs to be managed, not simply to be ‘fixed’. Even with many years’ experience in dealing with radon mitigation, a specialist contractor may not always solve the problem at the first attempt. No two buildings are identical, as is the geology beneath any two plots of land.

It is therefore imperative that a radon test is done after remediation works have been carried out, to determine whether they have been effective. Where very high levels of radon have been found in a building, it may take several attempts and various combinations of techniques to sufficiently lower the concentration of the gas.