Guidance

What to do in a radiation emergency

Updated 10 September 2024

Actions to take: go in, stay in, tune in 

There are important actions you should take to protect you and your family in the event of a radiation emergency.

Go in

The most important thing to do if you are told you are near a radiation emergency is go indoors as soon as you can and stay there. Close the doors and windows and stay as far away from external walls as possible.

Stay in

Staying indoors reduces your exposure to any radiation outside. You will be given advice on what to do next. Turn off all fans and air conditioning and close all external doors, windows and vents where possible. You will be given advice on what to do next. You may need to stay indoors for one to two days.

Tune in

Monitor the news and follow official UK advice on GOV.UK for what to do next. Any changes to advice will be communicated to you via official sources – this may be via the radio, television, internet, social media or the police.

Follow the local official advice

Emergency services and local authorities will provide information about what has happened and what you should do. This may be provided via the radio, television, internet, social media or the police.

What you need to do to protect yourself will depend on where you are in relation to where the radiation emergency is, so it is essential to follow the advice provided where you are. Radiation cannot be seen, heard, smelt, tasted or felt, so it is important that you follow the advice given to you, even if you can’t tell that anything has happened. If you are overseas, follow the local official advice.

You may be advised by the emergency services to evacuate, and you should be prepared to do this, if needed, following advice issued for your area. You should not evacuate unless advised to do so, as leaving shelter may increase your exposure to radiation.

If a radiation emergency happens outside the UK, it is very unlikely that you will need to do anything different from normal if you are in the UK at the time. Any official advice for the UK public will be given on the television, radio, internet or social media.

How these actions will help to protect you

Radiation emergencies are situations that could potentially lead to an increased risk of exposure to significant radiation, such as an incident at a nuclear power plant or an incident during the transport of radioactive material. Radiation emergencies are rare events, but we can greatly reduce their potential impact by being prepared for them, should one occur. The UK government, local authorities and organisations responsible for nuclear facilities both in the UK and overseas have detailed plans in place to protect the public in the event of a radiation emergency.

A radiation emergency may involve the release of materials (for example gases, dust and larger fragments) which are emitting radiation. These are known as radioactive materials.

In the event of a radiation emergency, people may be exposed by:

• breathing in radioactive materials
• direct exposure to radioactive material carried in the air and deposited on surfaces, clothing or skin
• eating or drinking food or water contaminated with radioactive materials

People who are in close proximity to a powerful source of gamma rays may be directly exposed to radiation but may not be contaminated with radioactive material. 

If there is a release of radiation, sheltering in a building made of robust and dense materials, such as those used for permanent buildings, will provide adequate protection from most radiation exposure. This is because, although certain types of radiation (gamma rays) can penetrate materials such as glass, plastic and metal, other types of radiation (alpha and beta) are less penetrating. Going inside the nearest building or staying in the building that you are already in, sometimes called sheltering in place, will also help to prevent you becoming contaminated with radioactive particles that could be inhaled or ingested. Further information on the different types of radiation and radioactive materials is available: Basic concepts of radiation.

The most immediately affected areas in a radiation emergency will generally be those within a few miles of the place where the radiation emergency has happened. As radioactive materials can be carried by the wind, it is possible that areas further away may also be affected, but generally the amount of radiation people are exposed to reduces with distance. The size and location of the area affected by the emergency will depend on a number of factors, including the scale of the emergency and the weather, particularly the speed and direction of the wind, at the time.

Actions that can be taken to reduce radiation exposure in an emergency are called protective actions. They are categorised by the timescale in which they need to be taken to maximise their benefits and include both urgent and longer-term protective actions.

Sheltering in place is one of the urgent protective actions that you may need to take to limit, reduce or avoid radiation exposures.

Other urgent protective actions that you may need to take include evacuation, taking stable iodine if advised, and following restrictions on food and water supplies. These actions would be implemented quickly for periods of hours or days, in order to protect against exposures received over relatively short timescales. More detailed guidance on these urgent protective actions is provided below.

Long-term protective actions may include prolonged restrictions on certain types of food and temporary or permanent relocation of people. Further information on long-term protective actions is available below.

Emergency services and local authorities will inform people within the affected area that they need to take immediate action. In most situations, if you are in the affected area, you will be advised to go in, stay in and tune in. The advice will change over time, as information on the radiation emergency becomes available, so keep updated with the official advice for your location. Official advice for the UK public will be given on the television, radio, internet or social media.

Short-term protective actions: more detailed guidance

This document has so far outlined the protective actions people should take in the event of a radiation emergency. The following sections provide more detail on each protective action and how they reduce radiation exposure in an emergency.

There is information in this section about:

Go in

Go into any building as soon as possible. Buildings made of brick, stone, concrete or similar materials provide the best protection, but being inside any building is better than being outside. If you are already inside a building, stay there.

If you have been advised to clean yourself or decontaminate, do this as soon as possible.

Close external doors and windows. Walls, closed doors and closed windows provide protection against the most harmful forms of radiation. The building will limit the movement of radiation into the air that you breathe in and will protect you from radiation outside.

As far as possible, stay in the middle of the building away from external doors, windows and walls, to avoid exposure from any radioactive material that has collected on the outside of the building.

Vehicles and tents do not provide sufficient shelter from significant radiation. If you are in a vehicle or tent, you should also get inside a building as soon as possible but this should be done in a safe and orderly manner; do not take unnecessary risks to reach suitable shelter.

Temporary buildings and caravans are considered to offer some protection and can be used so long as heating, water, food, and toilet facilities are available, if sheltering in a building is not possible.

Stay in (sheltering in place)

Staying indoors will protect you and others from exposure to radiation. In most cases you will be advised to stay inside for one to two days after a release. This could be longer if there is a prolonged release of radioactive material.

You should shelter in the nearest building if you are not already at home. Do not travel home to shelter there as this may take too long and put you at risk of being exposed to radiation. If possible, you should shelter in a building that has access to heating, drinking water, food and toilets.

Sheltering in place involves going into a building and closing external doors and windows. You should also turn off any equipment which brings air from the outside into the building (such as fans or air conditioning) and close any air vents, including trickle vents in windows, if you can. You should also turn off any fans that are circulating air within the building. This will reduce the amount of radioactive material being drawn into the building. Safety-critical ventilation systems may be left on, such as those that are there to prevent breathing in dangerous fumes, such as chemical treatment equipment.

If you need to take medication regularly for existing health conditions, you will be advised to seek advice from the NHS by contacting NHS 111 (online or by phone) rather than leaving the building.

You will be given additional instructions, including when it is safe to go outside. This may be via the radio, television, internet, social media, the police or via local official advice if overseas. 

If your family or friends are not with you, for example if they are at school, nursery, hospital or with other people, do not go to collect them if you have been informed to stay indoors. Going outside to collect them could expose both you and them to dangerous levels of radiation. People who are in schools, nurseries, hospitals or other facilities in the affected area will be given advice on what to do and will be asked to stay where they are until it is safe to move.

In some circumstances, you may be asked by the emergency services or local authorities to evacuate. If so, you will be given detailed instructions on what you need to do and how you will be supported. It is important that you do not evacuate unless advised to do so, as leaving shelter may mean you are exposed to radiation.

Self-decontamination 

If you were near to where the radiation emergency happened and were outside at the time, your clothes, skin and hair might have been contaminated with radioactive materials. The emergency services will provide information on the locations where this applies via channels such as the radio, television, internet and social media.

Removing this contamination will help to protect your health by reducing your radiation exposure. It will also help to prevent the contamination of the building that you are sheltering in, therefore reducing exposure of anyone else in the building. Contamination with radioactive material is not something that you can see, so it is important that, if you are advised to self-decontaminate, you do this as soon as possible, even if you think you are clean.

This self-decontamination should take place where you have taken shelter or, if you have already left the affected area, where you are located when you find out about the radiation emergency.

Studies show that simply taking off your outer clothing can remove around 90% of the contamination.

Do not use conditioner when washing your hair, as this can bind contamination to hair. Simple soaps or mild shampoos are effective for removing contamination.

Follow these step-by-step instructions on how to remove your clothing and decontaminate yourself safely.

These instructions also include how to help others who can’t decontaminate themselves and what to do about pets who may have been outside and exposed to radiation.

Pets

If your pet is outside with you when you are advised to go in, bring them indoors with you. If you are indoors and you don’t know where your pet is, do not go out to find them. This could harm your health.

If you have brought pets inside with you, or if they return home after you have gone indoors, decontaminate them by washing them with shampoo or soap and water as soon as possible and before they are handled further. You should wear waterproof gloves and a face mask if possible in accordance with the self-decontamination guidance. If you can’t decontaminate them, put them into an area away from people in the household.

Once you are indoors, do not let your pets out. Keeping your pets indoors will stop them being further exposed to radiation and prevent them bringing radiation into the home.

Evacuation

Evacuation is the temporary removal of people from an area to avoid or reduce short-term radiation exposure in a radiation emergency. It protects against breathing in radioactive material and from external exposure from radioactive material in the air and on the ground.

Evacuation is used in situations where sheltering is not possible or there is the potential for people to receive higher radiation doses over prolonged periods if they are to remain inside the buildings in the radiation emergency area. It may also be used as a precautionary protective action if there is sufficient time to evacuate safely.

If the authorities decide to evacuate your area, you will be given instructions by local emergency responders on what to do and where to go. This information may be provided via the radio, television, internet or social media.

After evacuation you may need to be checked for contamination or advised to self-decontaminate before going to a rest centre or other temporary accommodation. This will depend upon factors such as the wind direction and evacuation route as well as the specific types of radioactive substances that were being released at the time of evacuation. This advice will be issued by the emergency services at the time of the emergency.

Emergency responders will carefully consider the risks associated with evacuation before deciding whether it is necessary and in doing so will take into consideration people’s ability to evacuate by themselves or if they need help.

It is important that you follow the advice from emergency responders, as evacuating when not advised to do so may cause you to have a greater exposure to radiation than if you stay inside.

It is possible that you may have left an affected area before you knew that an emergency had happened. If this is the case, you will be advised to self-decontaminate as soon as you can after becoming aware of the emergency. It is important that you continue to follow official advice so that you know what to do next, as you may now be a considerable distance away from where emergency responders are deploying resources.

You should not return to the affected area until you are advised that it is safe to do so. Emergency planners have considered this risk so that specific advice for the emergency can be issued.

Stable iodine

Radiation emergencies at nuclear reactors that are operational, or have recently (within 90 days) shut down, may result in releases of radioactive forms of iodine which can accumulate in the thyroid gland and harm your health. Taking stable iodine tablets at the right time blocks the absorption of radioactive iodine by the thyroid gland and speeds up the body’s ability to remove radioactive iodine. This reduces the risk of harm from radioactive iodine exposure to the thyroid. Stable iodine does not protect against health effects from other sources of radiation.

If it is necessary for you to take stable iodine tablets, you will be given official advice from government or emergency services on how to get them, when to take them and how much to take. It is important that you only take the stable iodine tablets provided for this purpose and that you take them at the right time. A single dose provides protection for 24 hours, so taking the tablets too early may limit the length of time that you are protected for. Taking the tablets too late reduces the effectiveness of stable iodine and could lead to more harm than not taking the tablets at all.

Stable iodine must not be taken for the first time more than 24 hours after an exposure to radioactive iodine. This is because it can lead to the radioactive iodine already in the thyroid being retained there longer, thus increasing the radiation dose and causing more harm than benefit. Taking stable iodine tablets will not reduce any other type of radiation exposure.

It is important that you only take stable iodine tablets provided for this purpose. Other sources of iodine such as iodised salt should not be taken in the place of stable iodine tablets, as they will not provide the necessary protection and they may be dangerous to your health. As with any medication, it is important that you read the patient information leaflet before taking stable iodine tablets. See below for further information on stable iodine tablets.

Food and water sources: initial advice

Food and drink that are already indoors, including tap water and food and drink in shops, will be safe to consume. Covered or sealed food in homes, workplaces and shops will be also free of contamination once it has been removed from its wrapping or containers. This is because it is very unlikely to have been contaminated by radioactive materials, especially if it is within sealed containers.

You will be provided with further advice on any food that has been stored outside, including food you have grown yourself.

Mains water supplies (tap water) are unlikely to be affected immediately, as there is typically 2 to 3 days’ worth of treated water within the mains system in any given area; therefore this water is considered safe to drink unless you are informed otherwise. However, some homes use water collected from roofs and other surfaces or shallow wells, and it is possible that the contamination levels in these may exceed safe limits if they are close to the site of the release. Users of private water supplies (that is, not mains water) are required to register these with their local authority. This register will be used to identify those at risk who will be advised on the appropriate actions to take.

Water companies and local authorities will issue detailed advice on water safety and, where advice is issued to not drink water from mains or other supplies, safe alternative drinking water will be provided where possible.

Surface water (including water collected from outside surfaces such as tarpaulins) may be contaminated. You will be advised of any foods to avoid or any restrictions on water use. This will prevent you from eating or drinking any radioactive material that could be a risk to your health.

If you are near to a radiation emergency overseas, follow the local advice about food and drinking water supplies.

More information on potential long-term restrictions on food and water

People coming into the UK from overseas emergencies

Following a radiation emergency overseas, the UK Health Security Agency (UKHSA) will assess the risks to public health. UKHSA will work with government partners to assess the need to monitor and decontaminate people arriving into the UK in the unlikely event that they are contaminated with radioactive materials. If you are overseas at the time of a radiation emergency, follow the advice of the local emergency services and when safe to do so, contact the local British Embassy, Consulate or High Commission for advice on what to do next.

Continue to check for official advice – both in the UK and if overseas

The exact advice on what you should do will depend on the type and location of the radiation emergency. The advice will change over time, so keep up to date with the current information. Once the immediate emergency has passed, responders will take actions to recover from the emergency, and so it is important that you continue to monitor the news, GOV.UK and local official advice if overseas, for advice on what to do next.

Longer-term protective actions

Recovery actions

Actions that might be taken to reduce radiation exposure after the radiation release has stopped are called recovery actions.

Local authorities will engage with affected communities to agree the acceptable level of the remaining hazard carefully balancing the potential harms and benefits. The level is also determined based on guidance for local authorities and government on recovery options.

Most recovery actions will involve some disruption to the community and will create waste material which must be carefully managed. Examples of recovery actions include removal of topsoil and road surfaces, high pressure hosing of roads, using peelable coatings on pavements or roads, removing foliage and changing land use.

Depending on the nature of the radiation emergency, recovery may take a few weeks or could last for many decades. 

Temporary or permanent relocation 

Once any release has stopped and it is certain that it cannot restart, an assessment of the extent of contamination of the area affected by the radiation emergency will be undertaken. This is used to determine the level of residual risk posed by any radioactive material remaining in the environment. 

It may be necessary to temporarily move people out of an affected area to carry out certain recovery actions. For example, sweeping roads may temporarily increase the level of contamination in the air. Workers carrying out these activities will be protected using oversuits and high filtration masks which require training and fitting. It may be necessary and safer to move people out of the affected area while this work is carried out and monitoring is undertaken to check its effectiveness before people return. In some cases, it may be necessary to permanently exclude people from areas where the radiation exposure would be above agreed acceptable levels.

An ongoing programme of assessing the risks from radiation exposure and effectiveness of actions to reduce them will be introduced. 

Restrictions on food and water

Radioactive material that lands on the ground or onto bodies of water can contaminate crops, livestock and sources of drinking water. Contamination can be present on the outside of crops, such as fruit and leafy vegetables, and over time can be incorporated into crops through the roots. Livestock may also eat contaminated food such as grass, which can affect meat and dairy products.

If contamination of the land occurs, it is possible that the food standards agencies will place precautionary restrictions within a defined area on the sale of crops, livestock and animal products, such as milk, that have been harvested or collected after the release to protect the public. There will be guidance on eating homegrown produce, such as fruit and vegetables from allotments, in the affected area.

As more data becomes available, the area with precautionary restrictions is likely to be reduced to only those areas where they must be kept in place. Depending on the radioactive materials and foodstuffs involved, restrictions may be removed as radioactive decay reduces the levels of contamination. An ongoing programme of monitoring and risk assessment will be introduced. 

To protect water treatment plants, it may be necessary to stop the extraction of water from rivers, lakes or wells in the affected area. This may have an impact on water supply once treated water has been used up. Water companies have arrangements to provide alternative safe water for drinking such as bottled water; this is routinely used where there are disruptions to local supplies.

For large releases from overseas nuclear facilities it is possible that, if certain weather conditions occur, radioactive material carried by the wind may land in some parts of the UK. If this happens, it is possible that levels of contamination may be high enough to require restrictions on the sale of contaminated crops, livestock and dairy products within a defined area. This may especially be the case where rainfall occurs, which can increase the deposition of radioactive material from the air. It is also possible that certain supplies of drinking water may be affected; however, this is likely to be limited to a small number of private supplies that use surface-collected drinking water. 

Planning principles for protective actions

Sheltering in place

Sheltering provides a good level of protection from breathing in radioactive material compared to being outside, as well as from direct exposure to radioactive material in the air outside that has landed on the ground or on the exterior of the building. Gamma radiation can penetrate windows and to some extent walls, but radiation exposure from gamma radiation is much reduced by solid walls.

The amount of protection provided by sheltering will vary from building to building. In general, for a typical house, sheltering in place reduces the exposure from breathing in radioactive material by 40%, and reduces direct exposure by 85% compared to being outside. These dose reduction percentages are used by emergency planners to decide whether sheltering offers sufficient protection when planning for and responding to an emergency and are based on a number of scientific studies.

In general, because the amount of radioactive material present in the air reduces with increasing distance from the point of release, the benefits of sheltering to provide a reduction in radiation exposure decrease with the distance from the point of release. Emergency responders will review the distances at which sheltering leads to more harm than benefit and modify local advice accordingly.

Evacuation

Evacuation, if it is undertaken before a release occurs, is the only urgent protective action that has the potential to prevent virtually all exposure during a radiation emergency. If it is not possible to evacuate people before the release occurs, then careful consideration needs to be given to the risks and benefits of any evacuation and associated timings, including how long it will take to evacuate. In some cases, it might be safer for the population to shelter while exposure levels outside reduce.

Local conditions will be taken into account by decision makers to achieve an appropriate balance of risk between radiation exposure and evacuating. Factors may include adverse weather conditions (for example snow), evacuation routes that might take people closer to the point of release, ability of the population to evacuate and forecast changes to the radiation hazard. Emergency responders and local authorities will specifically consider the risks of evacuating vulnerable members of the community. 

Stable iodine tablets

The quantity of radioactive iodine released may be enough to justify the use of stable (non-radioactive) iodine by people who were within an assessed distance of the reactor. Beyond this distance, the use of stable iodine is unlikely to benefit people. The radioactive material released from a nuclear reactor is diluted as it travels away from the reactor. The need for stable iodine tablets also decreases with distance because people further away from the reactor will be exposed to lower concentrations of radioactive iodine in the air, therefore will be below the threshold at which stable iodine is required.

Taking stable iodine at the right time relative to when someone is exposed to radioactive iodine can block the uptake of radioactive iodine by the thyroid gland by flooding the gland with stable iodine, and so speed up the removal of any radioactive iodine from the body. This reduces the overall harm from radioactive iodine exposure.

Stable iodine is most effective if taken between 24 hours before and 2 hours after exposure to radioactive iodine. The effectiveness of stable iodine reduces the longer the time between exposure to radioactive iodine and taking the tablets, as radioactive iodine will already have been taken up by the thyroid gland, but it can still be useful up to 8 hours after exposure.

As a precaution, all nuclear reactor sites where there could be a risk of releasing radioactive iodine in an emergency have specific plans for the distribution of stable iodine and for the provision of advice to take tablets in the event of a radiation emergency. 

As with any medication, it is important that people read the patient information leaflet before taking stable iodine tablets. Stable iodine only protects the thyroid; it does not counteract other impacts of radiation.

Initial restrictions on food and water supplies

In a radiation emergency, there are maximum permitted levels (MPLs) of radioactive material per kilogram of food or per litre of milk, and action levels (ALs) for radioactive material in drinking water which apply in the UK. These MPLs and ALs are intended to protect the public from the long-term consumption of contaminated food and water that may present a risk to health, and as such the areas affected are likely to be larger than the areas where urgent protective actions are required. The MPLs and ALs apply in emergency situations only. They are set in order to avoid the public being exposed to unacceptable levels of radiation within food or water.

In the first few hours of a radiation emergency, it is unlikely that there will be sufficient data to know exactly where contamination is and how much there is, as factors such as localised rain and geographic features can have a large influence on where material lands. Responders, including UKHSA, will use computer modelling, together with data that is available, to assess the potential spread of material and so where monitoring needs to take place to confirm levels of contamination.

Further information

More detailed advice on public health protection in radiation emergencies, including information on how UK guidance has been developed, is available. 

Information on radiation, what it is and how it causes harm to health has been published by UKHSA. The Health and Safety Executive (HSE) has also published a useful guide to radiation which also looks at risks within workplaces.

Basic information on how the UK government prepares for emergencies at nuclear power facilities is available.

The UK government has published general guidance on preparing for all types of emergencies. You can also find about your local council’s emergency plans using a postcode search.

Detailed guidance for emergency planners and responders on the recovery from radiation emergencies is available.   

The Office for Nuclear Regulation has published information on the UK nuclear sites and facilities that it regulates.

Advice on food in England and Wales is issued by the Food Standards Agency, and in Scotland is issued by Food Standards Scotland.

Information on radiation monitoring within the UK in the event of an emergency is available.

Environmental protection advice in England is provided by the Environment Agency, by Natural Resources Wales in Wales, by Scottish Environment Protection Agency (SEPA) in Scotland, and by the Northern Ireland Environment Agency (NIEA) in Northern Ireland.

The United Nations’ International Atomic Energy Agency (IAEA) provides information on radiation emergency preparedness and response and international frameworks for protection of the public based on international legal instruments.

The World Health Organization (WHO) provides information on the health effects of radiation emergencies and guidelines on the use of stable iodine.

The European Commission publishes maps with information on radiation levels across Europe.