Radon FAQs

The Health & Safety Executive acknowledges that approximately 2000 people in the UK die from lung cancer linked to radon exposure each year.

It is a clear odourless radioactive gas that escapes naturally from the rock beneath the earth’s surface. In some regions the concentration is worse than others but, like all forms of ionising radiation, can be deadly.  Although geological maps provide some guide to the riskier areas of the UK, because of the nature of the gas high levels of radon can occur in many other parts of the UK.

The Government has set guideline maximum levels that radon concentration should be inside buildings. These are referred to as Action Levels, as they are the point at which it is advised (or required, in the case of commercial buildings) that action is taken to lower the concentration. In domestic properties, the current Action Level is 200 Bq/m³ [Becquerels per cubic metre] and in commercial properties the current Action Level is 400 Bq/m³. The average background radon concentration outside is 4 bq/m³ and the average radon level inside buildings is 20Bq/m³.

To put these levels into perspective, the estimated annual radiation dose that someone would receive from spending 8 hours per day in a building with 400 Bq/m³ is equivalent to undergoing approximately 225 chest x-rays. Put another way, the damage to the lungs from spending 8 hours in radon levels of 400 Bq/m³ is estimated as equivalent to smoking over 10 cigarettes during the same time period.

Radon gas seeps into enclosed spaces such as houses and other buildings where it collects. It can build up to high concentrations, depending upon the local geology, atmospheric conditions and ventilation in different structures. Radon itself also decays to form short-lived radioactive particles, which remain suspended in air. When such radioactive particles are inhaled into the lungs, they irradiate the lung and increase the risk of developing lung cancer. This risk increases as the level of radon and the duration of exposure increases. High radon levels therefore need to be taken seriously and steps taken to ensure exposure to radon is kept as low as reasonably practicable.

Properties that lie in certain areas of the UK are more likely to contain high levels of radon, due to the underlying geology and varying amounts of uranium present. The latest set of indicative maps published by the Health Protection Agency (HPA) shows that large areas of Northern England, the Midlands, the South Coast and the whole of Wales are also at risk. Areas such as these, where it has been estimated that more than 1% of properties will contain high levels of radon, are classed as radon Affected Areas.

The Radon Council has been advised that claims are sometimes made that certain properties are “free from radon”, based on their not being in a designated area. It should be understood that radon is a natural gas and even if the property is in a non-affected area it could still be affected with high levels of radon

Buildings with basements are also more susceptible to high levels of radon accumulating, as there is a larger surface area in contact with the soil through which the gas can permeate.

Unfortunately, the task is complicated by conflicting advice and recommendations ranging from geographic and geologic searches, to the withholding of sums of money (the so-called radon bond) if the property is in a designated part of the country. All of these involve unnecessary expense and risk blighting areas of the country needlessly. None can give reassurance other than a statistical probability. Isolated high levels of radon can crop up in the most unlikely places and conversely, low levels can be measured in property in supposedly high-risk areas.

Official advice has consistently been that only a long-term test of three months or more will be sufficiently accurate. Whilst it may be true that the longer the test the better in order to even out seasonal variations, it ignores the fact that shorter tests exist and if conducted correctly are able to provide a quick screening of a building. A prospective Purchaser is not normally concerned with the precise radon levels within a building, but wishes to know if the biggest purchase being made in their lifetime is likely to be injurious to the family!

If you live in parts of the UK called “Affected Areas”, or even if you don’t, the two essentials are, firstly don’t panic and secondly consider having a measurement of radon levels in a main living room or bedroom as a minimum. As mentioned later this may be particularly important if you are about to sell your property. Equally important is to demand that your conveyancing-solicitor obtains radon information about a property anywhere in the UK that you intend to buy.

It is also the only way to start reducing the unnecessary annual deaths from radon gas in properties both old and new.

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 Radon 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.

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.

Barriers (membranes) which are impermeable to radon can be laid across the footprint of a building during construction. It is important that these are installed by trained specialists, and not general groundworkers, as any gaps or splits in the material will allow the gas to pass through and can render the membrane useless. The current Building Regulations require newbuilds in certain parts of the country to incorporate radon protection.

The Radon Council advises that all property purchases request a radon screening test to be carried out before exchanging contracts. It is often the case that a prospective purchaser will conduct a damp and timber survey before going ahead with a purchase, and it would be prudent to also conduct a radon test. If the test result is close to or exceeds the Action Level, it may be appropriate to negotiate with the vendor to pay all, or part, of the cost of remediation.

A test using a detector posted to you for placement under instructions should be approximately £50 per house. After the given test period, you post back the detector and the company concerned subsequently posts you full written details on a confidential basis.

If you have a level near or above the “Action Levels” quoted above, depending on the nature of the property, remedial action may have to be considered. The Council’s list sorts out the various kinds of service on offer. Remedial work charges will obviously vary according to the size and construction of the property.

Written schedules outlining the reasons and nature of work and including costs should be offered for all work quotations. In the past, some consumers have obtained details of the recommended remedial work from a reputable Company and have then used these details and had the work done by inexperienced operators. As a consequence, several organisations now make a charge for such a schedule. You should check that this is refundable if the company is entrusted with the work.

Be advised that no one universal solution exists for radon treatment in existing buildings, therefore experienced contractors will be able to select a suitable method for your property. The Radon Council strongly recommends that radon detection and remedial work should be undertaken by persons trained and experienced in such work.

The current situation in the UK is that legislation exists for “new build” housing in defined areas for domestic occupiers and for employees in the workplace anywhere in the UK. For the much larger stock of older homes however, no resources are available for remedial work.

There has been a considerable effort funded by the tax-payer to identify problem regions now designated as “Affected Areas”. The lack of financial resources when readings above the 200 Becquerel level (Action Level) are found in homes means that a large proportion of houses or flats needing remedial work are left in their original state, which is clearly unacceptable from the human health point of view and several proposals have been put forward to deal with the problem. Discretionary grants although available have seldom been awarded.

The Radon Council has proposed the one UK system that avoids unnecessary bureaucracy and initiates remedial work with the provision of the necessary funds when that is clearly required. The BRE and The Radon Council are in broad agreement that with current prices. Approximately, the average costs of remedial action for a domestic house will be up £750 – £1,500. A few will cost more and some less. The proposal is that at the time of conveyancing (i.e. transferring ownership of a property), the results of a short term test (or preferably a longer term test if available) for radon be exchanged between the solicitors for the buyer and seller.

Should any remedial work be necessary then arrangements can be agreed for financing the work from the sale proceeds and for the mortgage loan being used for the purchase. The same kind of procedure would apply when tenancy documents are being prepared except that the onus would clearly be on the landlord to provide a property clean and fit for healthy occupation. These proposals would apply anywhere in the UK. They would also lead to an increasingly accurate picture of radon distribution throughout the country if the data could periodically be made available.

Other methods have been suggested or tried. For example, an indemnity insurance policy, or financial sum being retained as a kind of Bond. Such actions are not required if the results of a radon test are known. A Bond has the disadvantage of tying up sellers’ money together with associated costs.

For your own peace of mind, a test costing approximately £50 may well be a good investment. Keep a written record of the results against the day when you decide to sell. Only if your home requires remediation are you faced with a decision on taking action to reduce the level of radon gas.

Radon in the workplace

The Radon Council’ s full List of Contractors, Suppliers and Consultants offering Advice and Services Involving Remedial Work for Radon Gas can be found on this website.

Please note that the firms appearing on the List are approved by the Council and entitled to refer only to that fact on company stationery or publicity material. Such companies are not entitled to claim that they have been “certified” for their work or otherwise endorsed. You are advised to make sure that any list is current. If in doubt, please check with The Radon Council.