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Radon Gas - Reducing Levels in your Home

Radon - back to the facts

In any building, the air changes all the time - leaving and entering through doors, windows, cracks in the walls and through the floors.  As you probably already know, radon, a natural radioactive gas that comes mainly from the soil, has been found to cause lung cancer.  Radon is found everywhere in the soil and air; more is found in some areas than others.

How does radon get into my home?

Because of the effects of wind and temperature, the air pressure in your house is usually slightly lower than the air pressure in the soil beneath it.  Just as air rushes in to fill a vacuum because the pressure is lower, the same effect happens (much less dramatically) with houses - air from the soil creeps into the lower pressure area of the house through cracks and gaps in the floor or walls.  This air contains radon, and in areas where radon levels in the soil are quite high, indoor radon levels can rise above the Action Level.

Health studies from around the world have linked radon with lung cancer.  Radon is the second largest cause of lung cancer; the first is smoking.  People who are exposed to high levels of radon are more likely to get lung cancer, more so if they are smokers.  But even if you would find it difficult to cut down on smoking, you can take easy, relatively cheap and permanent steps to ensure that the levels of radon in your house are below the recommended Action Level, and therefore pose an acceptable level of risk.

Test your radon level

Scientists measure radon levels in becquerels per cubic metre (Bq m3).  The advice of the Government's independent advisers, the National Radiological Protection Board (NRPB) has led the Government to recommend that if your indoor radon level is above 200 Bq m3 (the Action Level) you should take steps to reduce it.  There is a test that measures levels of radon with a simple safe device for a period of three months.  It costs around £47, for two detectors and anyone can order it.  If you are thinking of having a test carried out, contact the Health Protection Agency on 01235 822622  

Further information including ordering an online radon risk report for your property, costing £3.53 is available on the Ukradon website This report will give an indication of the probability that a particular building will have levels of radon in excess of the Action Level.

Advice is available

The Building Research Establishment Ltd (BRE) has developed practical advice about how building work can reduce radon levels to within safe limits.  The Health Protection Agency advises on health risks posed by radiation and how to guard against them.  The Radon Council Ltd, an independent voluntary regulatory body, keeps a list of companies that are experienced in radon reduction work. 

Five ways to reduce radon

It is best to stop radon entering a house or, if that is not practical, to try to remove it if it gets in.  The aim in both cases should be to reduce indoor radon levels to significantly below the Action Level.  There are five main ways to achieve this.  Depending on the kind of house you live in and the amount of radon reduction you need to achieve, you can discuss the five ways with your builder - then find the one that best suits you, your house and your radon level.


            A            install a radon sump system

            B            improve ventilation under suspended timber floors

            C            use positive ventilation in your house

            D            seal cracks and gaps in solid concrete floors

            E            change the way your house is ventilated


The most effective (and usually most expensive) choice starts the list; the other choices vary in cost according to individual house needs, so they cannot be put in a strict order.  Don't forget that if your home's indoor radon level is not very far above the Action Level, one of the simpler choices may be adequate for your needs.

Don't forget that the Health Protection Agency, BRE and your local Council can provide advice, which will help you and your builder decide what type of radon reduction work will be most effective for your home.

Time for action

If you don't know that radon level in your home and are worried, take the test.  Remember that the Government, the NRPB and the BRE all recommend that if your indooor radon levels are above the Action Level, you should take radon-reducing measures as soon as practical - and then take the test again to give yourself peace of mind.

If you are worried about costs, remember;

Many of the methods are simple, and DIY work can reduce costs enormously;

The building societies have agreed in principle to provide loan finance for radon work, subject to the applicant's status;

If you cannot afford to pay for the work, it may be worth speaking to your local authority.  Discretionary ‘house renovation' grants may be available.  The authority will assess your eligibility and will determine how much, if any, of the cost you will have to pay.  Agreement for a grant must be obtained before the work is carried out.

As well as the explanations and recommendations that apply to individual methods, there are three extra points you should consider:

Chimneys and heating

If you have chimneys you don't use, it's better that you block them up: chimneys tend to draw air out of a room.  If you decide to block a chimney permanently, you need to stop condensation from building up inside.  Cap the stack with a chimney-pot hood and provide a small ventilation opening of about 50 x 20 mm in the block fireplace.  The BRE Defect Action Sheet 93 deals with this in greater detail.

If you have an open-flue gas, coal or oil-fired heater, make sure that enough fresh air gets into the room from outside the house.  Open coal or wood fires draw large volumes of air out of a room, even when the fire has a direct under floor supply of air.  If you can heat your room without an open fire, you should consider blocking up the chimney.

If you are planning to put in or renew a boiler or fire, ask your supplier to recommend a ‘balanced-flue, room-sealed' type.  This kind is helpful for people taking measures to reduce indoor radon levels, because the boiler or fire takes all the air it needs for combustion - and lets out the exhaust gases - through one metal grille in an outside wall, drawing no air from outside the house.  If replacing your boiler you might have to change its location, in which case professional advice would be helpful.

Landfill gas

In the very rare cases where a house needing radon work is on or next to a landfill site or coal mine, additional precautions may be needed to deal with methane that rises from the site.  If you have any reason to think that this applies to your house, ring your local authority's Environmental Health Department to check.  If there is a problem, you will be able to get expert advice from the BRE's radon hotline.


·        If you own your own home but have a mortgage

You may need the lender's permission before carrying out major changes to the house.  Your lender will be able to tell you what the mortgage agreement says and you should check this before starting work.


·        If you are a tenant

You will need to discuss the work with your landlord before you start.  You may be able to carry out some of the jobs yourself, but others, especially if they affect the buildings structure, might have to be carried out by the landlord.


·        Planning permission or Building Regulations approval

Are not usually necessary for small radon reduction jobs (unless you are making bigger changes at the same time).  Your local council's Building Control Officer can give you the advice you need.  However, if your house is a listed building, or in a designated area of outstanding natural beauty, a national park or a conservation area, you may need permission for any work that alters its external appearance.  Check with the Planning Department of your local council.

Further information

You can get an information pack on radon in the home, with advice about radon, its health risks and details of how to order the test from the Health Protection Agency Radon Freephone on 0800 614529 (or by post from Radon Survey Health Protection Agency , Chilton, Didcot, Oxon OX11 0RQ) ; and

Alternatively you can also contact the Domestic Public Health Team, Pembrokeshire County Council, County Hall, Haverfordwest SA61 1TP 01437764551 for further advice.

For a list of companies experienced in radon reduction work, write to the independent voluntary regulatory body:

The Radon Council Ltd
PO Box 39
Middlesex TW17 8AD
Tel:  01932 221212
Fax:  01932 229779 

Tel: 01437 775616

ID: 6190 Revised: 23/3/2016