Guidance

What to do in a chemical emergency

Published 10 October 2024

Introduction

The production, use and storage of chemicals is regulated to reduce risks to the public and the environment, however accidental or deliberate release can have serious impacts.

Some chemicals cannot be seen, smelt, tasted or felt, so it is important that you follow the advice given, even if you can not tell that anything has happened.

Just because a chemical is present does not mean that it will be harmful. How harmful a chemical is depends on how much of the chemical you are exposed to and for how long. It is important to try and reduce the amount and time of exposure to make harm less likely.

Actions to take

More detailed guidance is provided in later sections.

Remove, remove, remove

Follow the remove, remove, remove advice:

1. Remove yourself from the immediate area to avoid further exposure to the substance. Fresh air is important. If the skin is itchy or painful, find a water source. Report to the emergency services.

2. Remove your outer clothing if affected by the substance. Try to avoid pulling clothing over your head if possible. Do not smoke, eat or drink. Do not pull off clothing stuck to skin.

3. Remove the substance from your skin using a dry absorbent material to either soak it up or brush it off. Rinse continually with water if the skin is itchy or painful.

Go in, stay in, tune in

If you are outside and are alerted to a chemical emergency nearby then you should shelter – go in, stay in, tune in.  Emergency services will update on which areas should shelter and for what duration. The distance from the release and direction affected may change over time.

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
• emergency services

What you need to do to protect yourself will depend on where you are in relation to where the chemical emergency is, so it is important that you follow the advice provided for where you are. If you are overseas, follow the local official advice.

You may be advised by the emergency services or your local authority to evacuate. Further information is in ‘Evacuation’ below.

If a chemical emergency happens in a different part of the country, or outside the UK, it is very unlikely that you will need to do anything. Any official advice for the UK public will be given on the television, radio, internet or social media.

Detailed guidance on short-term protective actions

Remove, remove, remove

Remove yourself from the source

If you are close to a chemical release, move away as quickly as possible. If you can tell which way the wind is blowing, ideally you should move upwind, the direction where the wind is coming from, avoiding the source of the chemical. This will reduce your overall exposure.

If you have been contaminated and it is safe to do so, for example if the release has stopped and you are in fresh air or you are instructed to do so by emergency services, start decontamination as soon as possible to remove the chemical from you to reduce your overall exposure.

Remove your outer clothing if you are contaminated

If you are near the scene of a chemical release when it happens, your clothes, skin and hair might have been contaminated with hazardous chemicals. The emergency services will provide information on the locations where this applies either in person or via the radio, television, internet and social media.

Removing this contamination will help to protect your health. Contamination from hazardous chemicals may not be something that you can see, so it is important that if you are advised to self-decontaminate that you do this as soon as possible, even if you think you are clean.

Simply taking off your outer clothing can remove around 90% of the contamination. It is important to try to avoid pulling any clothes over your head.

Remove the substance (decontamination)

It is important to remove any substance from your skin and hair as quickly as possible. Use any available dry absorbent material, such as a paper towel or any fabric material, to soak up or brush off the chemical.

However, if the substance is irritating to skin, eyes or lungs, or if you are instructed to do so, and water is immediately available, wash with copious amounts of water. If water supplies are limited, concentrate on affected areas such as eyes or irritated skin.

If no water is available then remove the substance from your skin using a dry absorbent material, as above, and then as soon as possible rinse any irritated area with water.

Decontaminate yourself first, then follow the same steps to help children or others who need assistance.

In the first few hours of a chemical emergency, it is possible that there will not be sufficient information to know the exact area 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 and specialists will use computer modelling with available information to assess the potential spread of any chemical material and whether monitoring needs to take place, to confirm levels of contamination.

Go in, stay in, tune in

Follow the actions described in this section if you are outside and are alerted to a chemical emergency nearby.

Go in

As soon as possible, go into any building, other than the same building as the chemical emergency. If you are already inside a building, stay there.

Close external doors and windows. The building will limit the movement of chemical contamination from outside into the air you breathe in and will protect you from any high levels of hazardous chemicals outside.

If you have gone indoors while contaminated or have been advised to decontaminate (see ‘Remove, remove, remove’), do this as soon as possible. Some chemicals cannot be seen, smelt, tasted or felt, so it is important that you follow the advice given to you, even if you can’t tell if you have been exposed.

If you are in a vehicle, you should get inside a building as soon as possible because vehicles do not provide sufficient protection from contaminated air outside, which can leak into the vehicle.

Stay in (sheltering-in-place)

Staying indoors will protect you from exposure to chemicals. You may be advised to stay inside for a number of hours. How long will depend on when the release is stopped, how the chemical spreads, and if any immediate clean up is needed.

Sheltering in place involves going into a building, 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 possible. Turn off any fans that are circulating air around within the building as well, this will reduce the amount of chemical being drawn into the building. Safety-critical ventilation systems (such as chemical filtration or treatment equipment) may be left on, as these are designed to prevent breathing in dangerous fumes.

Sheltering in place reduces exposure and harm from breathing in contaminated air compared to being outside. Emergency services, public health and other responding agencies will decide how long sheltering is required to ensure sufficient protection during an emergency.

Sheltering in place may be required for a number of hours depending on the circumstances of the emergency. If possible, you should shelter in a building which has access to heating, drinking water, food and toilets. People who need to regularly take medication for existing health conditions should seek advice from the NHS by contacting NHS111 (online or by phone) rather than leaving the building they are in.

Vehicles and tents do not provide adequate protection. If you are in a vehicle or tent, you should 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 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.

If your family or friends are not with you, for example they are at school, nursery, hospital or with other people, do not go to collect them if you have been advised to stay indoors. Going outside to collect them could expose both you and them to dangerous levels of hazardous chemicals. 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.

Tune in

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

In some circumstances, you may be asked to evacuate by the emergency services or your local authority. If you are asked to evacuate (see ‘Evacuation’), 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 high levels of hazardous chemicals outside.

Pets

If you and your pets are outside when you are advised to shelter, bring them indoors with you. If you are not contaminated and, to your knowledge, your pet is not contaminated, then you do not need to take any action to decontaminate them unless the emergency services have advised you to.

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 your pet is contaminated or returns home after you have gone indoors, decontaminate them as soon as possible and before they are handled further. Decontaminate them as follows:

• wear gloves and ideally eye protection
• rinse their eyes with water
• wash them with water and shampoo or soap

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

Evacuation

Evacuation is used in situations where sheltering is not possible or there is the potential for people to receive higher chemical exposure if they were to remain inside the buildings. If there is enough time before an area becomes contaminated, evacuation may be used as a precautionary protective action.

Any evacuation from an area would be arranged by the emergency services, usually only after an assessment of the relative safety of evacuation versus sheltering in place.

Evacuation, if it is undertaken before a release occurs or impacts an area, is sometimes used to help prevent exposure during a chemical 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.

If the authorities decide to evacuate your area, you will be given instructions by emergency responders on what to do and where to go. This information may be given out 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 type and nature of the hazardous chemical being released. This advice will be issued by the emergency services.

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 mean you have greater exposure to hazardous chemicals than if you stay inside.

If you have been in the area affected by the chemical release, but you left the area before you knew that an emergency had happened, it is possible you may be contaminated. In this event, you will be advised to self-decontaminate as soon as you can. It is important that you continue to follow official advice so that you know what to do next even if you are now 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 responders, public health and other responding agencies will consider the risks so that specific advice for the emergency can be issued.

Food and water sources: initial advice

Food and drink which is 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 also be free of contamination once they have been removed from their wrapping or containers. This is because it is very unlikely to have been contaminated, 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.  

Apart from incidents directly impacting the water treatment infrastructure, 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. 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. If required, this register will be used to identify those people and provide them with advice on the appropriate actions to take.

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

Surface water (including water collected from outside surfaces such as tarpaulins) may also be affected. If this happens, you will be advised of any restrictions on water use. This will prevent you from eating or drinking any hazardous chemicals that could be a risk to your health.

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

More information on potential long-term restrictions on food and water can be found below.

People coming into the UK from overseas emergencies

Following a chemical emergency overseas, on your return to the UK the risk will be assessed by public health or government partners to decide on the need to monitor you on arriving in the UK. If you are overseas at the time of a chemical 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 chemical 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 hazardous chemical exposure after the immediate chemical release has stopped are called recovery actions.

Once the emergency response has been completed, public health, local authorities and other government agencies will work together to determine if there is any remaining chemical hazard and assess recovery options. Local authorities will communicate with affected communities on any work required to return to safe levels. The level is also determined based on guidance for local authorities and government on recovery options.

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

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

Temporary or permanent relocation

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 personal protective equipment such as over suits 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.

An ongoing programme of assessing the risks from hazardous chemical exposure and the effectiveness of actions to reduce them will be introduced if needed.

Restrictions on food and water

Hazardous chemicals which land 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 be affected by eating contaminated food such as grass which can affect meat, eggs 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 issued on eating homegrown produce, such as fruit and vegetables from allotments, in an affected area.

As more data becomes available, the area with precautionary restrictions is likely to be reduced to focus only on those areas where they are required. Any restrictions on the sale of contaminated food or livestock and on the use of certain water supplies will be reviewed, and the area subject to restrictions may change. Any further advice on food restrictions will be given by food standards agencies, with advice on water use being provided by water companies.

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.

Further information

Advice on initial decontamination for incidents involving potentially hazardous substances is available.

UKHSA has published a report on: Protective actions during chemical incidents and fires: evacuate or shelter-in-place?

Information on some of the commonplace hazardous chemicals and how they may cause harm to health have been published by UKHSA. The Health and Safety Executive (HSE) has published information on the regulatory controls on large chemical facilities and a guide to the Control of Substances Harmful to Health (COSHH) which looks at risks within workplaces.

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.  Specific guidance for CBRN incidents is available for recognise and respond and clinical management and health protection.

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

Health is devolved in the UK and advice on public health in England would be given by the UK Health Security Agency (UKHSA), Public Health Scotland in Scotland, Public Health Wales in Wales and HSC Public Health Agency in Northern Ireland.

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

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.

Annex 1. Specific hazardous chemicals

This annex contains further information on some specific hazardous substances:

Carbon monoxide

Carbon monoxide is a colourless, tasteless, odourless, non-irritating gas which is most commonly made by combustion systems, such as engines. It can also be produced by:

• faulty boilers
• faulty gas appliances (fires, cooking equipment)
• using barbecues or generators indoors
• deliberately by mixing certain chemicals together

Exposure to carbon monoxide could be deliberate or accidental.

Carbon monoxide only affects the body when inhaled. It doesn’t irritate the eyes or skin so it can be hard to notice when you are being exposed to it, especially in small concentrations.  Common symptoms include headache and dizziness.

At high concentrations, carbon monoxide can cause permanent damage to your body, and in more serious cases can result in death.

If you might have been exposed to carbon monoxide, you should be assessed and advised by emergency services. Even if you have been assessed and discharged by the emergency services, seek medical advice if you develop any symptoms, such as fainting, breathing difficulties, feeling sick or headache.

Further information on carbon monoxide health effects, incident management and toxicology is available here.

Opioids

Opioids are a class of pain relief medications, including morphine and codeine, and more potent opioids such as fentanyl and related substances.

Opioids could be released in the form of powders or aerosols.

The toxicity of an opioid depends on the opioid involved, amount, and how someone is exposed to it.

Opioids could be absorbed into the body by inhalation, injection or ingestion. Symptoms caused by exposure to opioids include decreased consciousness, changes in vision, pinpoint pupils, and effects on breathing. Exposure to opioids can be fatal.

Symptoms can occur very quickly after inhaling or injecting a significant dose of opioids, as they are rapidly absorbed into the bloodstream. If you are exposed only by skin contact, for example to a powder, symptoms will not occur as quickly as with inhalation or injection. Exposure to a small amount of opioid only to the skin is unlikely to lead to harmful effects, especially if the contaminated skin is promptly washed with water.

People who have been exposed to opioids can be given naloxone, a medication which rapidly reverses the effects of opioid poisoning.

If you might have been exposed to an opioid substance, for example by contact with a powder or breathing in an aerosol, you should decontaminate and be assessed and advised by emergency services. After you have been assessed and discharged by the emergency services, seek medical advice if you develop any symptoms of concern, such as breathing difficulties nausea or changes to consciousness in the hours after you were exposed.

Safety recommendations for first responders are available here.

Hydrogen cyanide

Hydrogen cyanide is a volatile liquid or colourless gas. It has a faint bitter almond odour, although not everyone is able to detect this.

Exposure to hydrogen cyanide could be deliberate or accidental. If there is a release of hydrogen cyanide, you may be exposed to it in the following ways:

• breathing in (inhaling) hydrogen cyanide
• eating or drinking (ingesting) food or water contaminated with hydrogen cyanide
• ingesting hydrogen cyanide if you touch a surface that has been contaminated and then put your fingers in your mouth

Hydrogen cyanide is most dangerous as a gas, however, there is also potential for contact with hydrogen cyanide as a liquid or from cyanide salts such as potassium cyanide.

Symptoms of hydrogen cyanide exposure are different depending on how much you are exposed to, and how you are exposed to it. Symptoms can also start at different times after exposure. Common symptoms include effects on breathing, changes to mental state (confusion, anxiety, excitement) and loss of consciousness.

Hydrogen cyanide can cause permanent damage to your body, and in more serious cases can result in death.

If you might have been exposed to hydrogen cyanide, for example by contact with the liquid or its vapour, after you have been decontaminated you should be assessed and advised by emergency services. If you are assessed and discharged by the emergency services, seek medical advice if you develop any symptoms of concern, such as breathing difficulties.

Further information on hydrogen cyanide health effects, incident management and toxicology is available.

Hydrogen chloride

Hydrogen chloride can be a gas or liquid with a strong smell. It can be created by mixing chemicals together (for example bleach and an acid).

Exposure to hydrogen chloride could be deliberate or accidental. You may be exposed during a release of hydrogen chloride in the following ways:

• breathing in (inhaling) hydrogen chloride
• having hydrogen chloride gas come into contact with eyes or skin

Hydrogen chloride can cause irritation to the lungs, eyes and skin, a tight chest, headache, fever and wheezing, and in more serious cases can result in permanent lung or eye damage.

As hydrogen chloride is immediately irritating, most will flee from the vicinity of the release and this may limit exposure.

If you might have been exposed to hydrogen chloride, after you have been decontaminated you should be assessed and advised by emergency services. After you have been assessed and discharged by the emergency services, seek medical advice if you develop any symptoms of concern, such as breathing difficulties or skin symptoms in the hours after you were exposed.

Further information on hydrogen chloride health effects, incident management and toxicology is available here. Some sections are also relevant to high concentration hydrochloric acid.

Hydrogen fluoride

Hydrogen fluoride is a corrosive, colourless gas or volatile liquid with a strong odour which forms hydrofluoric acid when dissolved in water. Contact with hydrogen fluoride can cause extremely painful, deep burns which take a long time to heal.

Exposure to hydrogen fluoride could be deliberate or accidental. You may be exposed during a release of hydrogen fluoride in the following ways:

• breathing in (inhaling) hydrogen fluoride
• having hydrogen fluoride come into contact with your skin or eyes

Inhaling hydrogen fluoride gas can cause irritation of the eyes and nose with a sore throat. It can also cause headache, confusion, shortness of breath and coughing up blood. Contact with the eyes can cause serious eye injury which may take a while to develop. Skin contact with hydrofluoric acid can cause severe skin burns. It can also be absorbed by your body and cause effects on your nervous system and heart.

If you might have been exposed to hydrogen fluoride, after you have been decontaminated you should be assessed and advised by emergency services. If you are assessed and discharged by the emergency services, seek medical advice if you develop any symptoms of concern, such as breathing difficulties, irritation of the eyes or nose, headache, confusion or shortness of breath. Hydrogen fluoride can give you immediate extreme pain in the area which has been affected, but there might not be any visible injury for hours or even days later. If you experience pain following possible contact with hydrogen fluoride, you should seek medical advice even if you don’t have any visible injuries.

Further information on hydrogen fluoride health effects, incident management and toxicology is available here. Some sections are also relevant to hydrofluoric acid.

Hydrogen sulphide

Hydrogen sulphide is a colourless gas with a characteristic smell of rotten eggs. Individuals will react differently to the odour of hydrogen sulphide. Some people may be more sensitive to hydrogen sulphide odour than others. The human nose is very sensitive to odours and often detects odorous chemicals, such as hydrogen sulphide, at concentrations in air which pose no risk to health. As the hydrogen sulphide concentration increases, more people would be expected to have symptoms.

Exposure to hydrogen sulphide could be through accidental or deliberate release.

Symptoms of hydrogen sulphide exposure will depend on concentration and duration, but symptoms can include breathing difficulties, eye irritation, headache and dizziness.

If high concentrations of hydrogen sulphide are inhaled, it can cause collapse, cardiac arrest and death.

If you might have been exposed to high concentrations of hydrogen sulphide you should be assessed and advised by emergency services on scene. After you have been assessed and discharged by the emergency services, seek medical advice if you develop any symptoms of concern, such as breathing difficulties, eye or skin irritation, or muscle weakness.

Further information on hydrogen sulphide incident management and toxicology is available here.

Phosphine

Phosphine is a colourless gas. Phosphine can be released from certain rat poisons or fumigation tablets, and in these cases, it can smell like garlic or rotten fish.

Exposure to phosphine could be deliberate or accidental, for example, due to lack of training when using rat poisons. You may be exposed during a release of this gas in the following ways:

• breathing in (inhaling) phosphine
• eating or drinking (ingesting) food or water contaminated with phosphine gas generating chemicals
• ingesting the phosphine producing material (for example, rat poison) if you touch a surface that has been contaminated and then put your fingers in your mouth

Phosphine is most likely inhaled, as it is a gas, however ingesting chemicals which can release phosphine will have very similar health effects.

The first symptoms of exposure can be non-specific including respiratory problems, dizziness and nausea.

Phosphine can cause permanent damage to your body, and in more serious cases can result in death.

If you have been exposed only to phosphine gas you will not generally need decontamination. If you have been exposed to phosphine forming chemicals, then after dry decontamination, (removal of clothes and powder) you should be assessed and advised by emergency services. After you have been assessed and discharged by the emergency services, seek medical advice if you develop any symptoms of concern, such as breathing difficulties or shaking.

Further information on phosphine health effects, incident management and toxicology is available here.

Ricin and abrin

Ricin and abrin are toxins that come from plants (castor beans and rosary peas or jequirity beans).

It is highly unlikely that the public would be exposed to these substances accidentally; it is most likely that people would only be exposed to ricin or abrin due to a deliberate release of these chemicals.

If there is a release of ricin or abrin, you could be exposed to these toxins in the following ways:

• breathing in (inhaling) ricin or abrin
• eating or drinking (ingesting) food or water contaminated with ricin or abrin
• ingesting ricin or abrin if you touch a surface that has been contaminated and then put your fingers in your mouth
• by ricin or abrin entering your bloodstream (for example, if they are injected)

Ricin and abrin are more toxic if they are injected or inhaled than if they are ingested. If ricin or abrin are ingested, they are mostly digested within your body before they can be absorbed into your bloodstream, and so the risk of harm is much smaller compared to inhalation or injection. Ricin and abrin are not absorbed through skin.

Symptoms of ricin and abrin poisoning usually start several hours after exposure and include breathing difficulties, stomach symptoms or drowsiness.

Both toxins can cause permanent damage to your body, and in more serious cases can result in death.

If you might have been exposed to ricin or abrin, for example by contact with a powder or aerosol, after you have been decontaminated you should be assessed and advised by emergency services. After you have been assessed and discharged by the emergency services, seek medical advice if you develop any symptoms of concern, such as breathing difficulties, stomach symptoms or drowsiness in the hours after you were exposed.

Further information on plant toxins is available here.

Blister agents

Blister agents, such as sulphur mustard (called ‘mustard gas’, though they are usually oily liquids), are named for their ability to cause severe chemical burns.

It is highly unlikely that the public would be exposed to these substances accidentally; it is most likely that people would only be exposed to blister agents due to a deliberate release of these chemicals. If there is a release of blister agents, you could be exposed in the following ways:

• if the blister agent comes into contact with your eyes or skin
• by touching a surface that has been contaminated with the blister agent
• breathing in (inhaling) the vapours of a blister agent
• eating or drinking (ingesting) food or water contaminated with the blister agent

Blister agents are rapidly absorbed through the skin and eyes. They also easily penetrate clothing and so can damage even covered skin.

Symptoms of blister agent poisoning may be delayed after exposure and include skin irritation and blistering, eye irritation or breathing difficulties.

Blister agents can cause permanent damage to your body, and in more serious cases can result in death.

If you might have been exposed to a blister agent, for example by contact with the liquid or its vapour, after you have been decontaminated you should be assessed and advised by emergency services. After you have been assessed and discharged by the emergency services, seek medical advice if you develop any symptoms of concern, such as skin irritation, eye irritation or breathing difficulties in the hours after you were exposed.

Further information on the blister agent mustard gas is available here.

Nerve agents

Nerve agents are man-made chemicals that are highly toxic. Most nerve agents are organophosphates, some of which are liquids which can evaporate into air. Examples include sarin, VX and novichok.

It is highly unlikely that the public would be exposed to these substances accidentally; it is most likely that people would only be exposed to nerve agents due to a deliberate release of these chemicals.

If there is a release of nerve agents, you may be exposed in the following ways:

• breathing in (inhaling) the vapours of a nerve agent
• eye or skin contact with the nerve agent
• by touching a surface that has been contaminated with the nerve agent
• eating or drinking (ingesting) food or water contaminated with the nerve agent

Symptoms of poisoning by nerve agents can occur rapidly (within seconds or minutes) after inhalation and ingestion, but more slowly after skin exposure. Symptoms could include muscle twitching, painful blurred vision with smaller or larger pupils, breathing difficulties or stomach symptoms.

Nerve agents can cause permanent damage to your body, and in more serious cases can result in death.

If you might have been exposed to a nerve agent, for example by contact with the liquid or its vapour, after you have been decontaminated you should be assessed and advised by emergency services. After you have been assessed and discharged by the emergency services, seek medical advice if you develop any symptoms of concern, such as muscle twitching, painful blurred vision with constricted or dilated pupils, breathing difficulties or stomach symptoms in the hours after you were exposed.

Further information on nerve agent incident management is available here.

Tear gas, pepper sprays

Tear gas or pepper sprays, often classified as personal protection or riot control agents are a group of chemicals occasionally used by police to disperse crowds or temporarily incapacitate people at risk of causing harm.

Riot control agents usually affect the eyes causing immediate crying, stinging and burning. They also affect the respiratory system, causing a painful runny nose, burning pain in the throat, hoarseness, voice loss, excess saliva, chest tightness, feeling of suffocation, coughing and sneezing.

Riot control agents can be absorbed into the body by inhalation and through the skin. It is unlikely you would ingest (eat or drink) food contaminated with riot control agents.

As riot control agents are immediately irritating, most will attempt to flee from the vicinity of the release and this may limit exposure.

Symptoms caused by exposure to riot control agents usually improve within minutes once exposure has stopped. People who have been exposed do not normally require medical treatment.

Riot control agents are unlikely to cause long term effects, unless you are exposed to a high concentration of them for a long time within a confined space.

It will usually be obvious if you have been exposed to riot control agents because their effects are immediate. If you might have been exposed to riot control agents, for example by contact with a powder or aerosol, you should be assessed and advised by emergency services. After you have been assessed and discharged by the emergency services, seek medical advice if you develop any symptoms of concern, such as breathing difficulties or skin irritation in the hours after you were exposed.

Further information on riot control agents is available here.