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Radon

Radon is a colourless, odourless radioactive gas. It is formed from the radioactive decay of the small amounts of uranium that occur naturally in all rocks and soils around the UK.

For most of us, our greatest exposure to radiation is through radon.

Radon is the second leading cause of lung cancer after smoking.  

Why is radon a risk to health?

The radioactive elements formed by radon can be inhaled into our lungs. When inside the lungs, these elements continue to emit radiation that cause localised damage which can lead to lung cancer.

Radon causes over 1,100 deaths from lung cancer each year in the UK. Half of these deaths occur among those who are current smokers.

The higher the radon levels and the longer the exposure to it, the greater the risk – especially if you smoke.

Where is radon found?

Radon levels are low everywhere outdoors. In most cases the level of radon indoors is low and the risk to health is small.  However, indoor level of radon depends on the ground below and how the building is used.

You can check if you are in a radon affected area or ‘hotspot’  by using an indicative map, produced by Public Health England and British Geological Survey,  available from UKRadon.

The darker the colour, the greater the chance of a higher radon level indoors. If you live or work in or near a radon ‘hotspot’ we advise that you measure the levels indoors.

Measuring radon in the home and other buildings

The level of radon in a home or building cannot be predicted reliably, so needs to be measured with a radon detector. Radon can get into buildings from the ground below and varies from home to home and by lifestyle.
Radon detectors are safe and simple to use e.g. they can sit on a shelf. They are small hollow plastic shells containing a piece of clear plastic that records the damage caused by radon.

The detectors do not release or collect anything dangerous. However, they can be damaged by heat or submersion in water and should not be opened.

The amount of radon varies over time and from room to room in a home. The test is carried out over three months to allow for variations in levels.

The test is to determine your exposure, therefore, we recommend testing the living area and bedroom as these are the rooms you and your family use the most.

What level of radon is a cause for concern?

Radon is measured in Becquerels per cubic metre of air (Bqm-3). The average level in UK homes is 20 Bqm-3.

For levels below 100 Bqm-3, your individual risk remains relatively low and not a cause for concern. However, the health risk increases as the radon level increases.

Within domestic properties Public Health Wales recommends that radon levels should be reduced where the average is more than an Action Level of 200 Bqm-3. This Action Level refers to the annual average concentration as measured using two detectors (in a bedroom and living room) over three months, to average out short-term fluctuations.

A Target Level of 100 Bqm-3 is the ideal outcome for remediation works in existing buildings and protective measures in new buildings.

If the result of a radon assessment is between the Target and Action Levels, action to reduce the level should be seriously considered, especially if there is a smoker or ex-smoker in the home.

For workplaces health and safety legislation requires employers in radon ‘hotspots’ to assess radon exposure.  This duty also applies to any workplace where there are underground workplaces, even if they are not in a radon hotspot. The Ionising Radiations Regulations 2017 come into effect where radon is present above 300 Bqm-3 (annual average). Employers must take action to reduce radon exposure in these cases.

Actions to remedy/reduce exposure

Some simple actions such as sealing around loft-hatches and large openings in floors, and extra ventilation may reduce exposure however, they do not reduce radon levels on their own. These actions should be combined with other effective measures.
Examples of effective measures include:

  • Radon sump – an active radon sump, fitted with a fan, is the most effective way to reduce indoor radon levels. Sumps work best under solid floors and under suspended floors if the ground is covered with concrete or a membrane. Occasionally, passive sumps without a fan may reduce radon levels. 
  • Positive ventilation – a small quiet fan blows fresh air, usually from the roof space, into the building. 
  • Natural under-floor ventilation – many homes and some workplaces have a suspended ground floor with a space underneath. Good ventilation of this space can reduce radon concentrations. 
  • Active under-floor ventilation – a fan is used to either continuously blow air into or extract air out from the space below a suspended floor. This can be used when natural under-floor ventilation is inadequate to reduce radon level. 

More information