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This article is for Medical Professionals

Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find one of our health articles more useful.

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A major incident may be declared when local services have the potential to be overwhelmed.

The problem

Disasters happen and when major disasters strike they put considerable strain on the system. This may be partly because of the potential scale of the number of injuries but also because a major event can disrupt the infrastructure that should help to deliver relief. The nature of the problem may be a major outbreak of an infectious disease, a massive accident, a natural disaster or even an act of terrorism. The matter may be compounded by panic by those caught up in the disaster and there will be the long-term sequelae to manage - eg, decontamination issues, accommodation problems and psychological impact.

Location of the problem

Major cities are most at risk, especially from terrorism which may involve not just explosions but chemical, biological or even nuclear attack. However, it would be wrong for rural areas to neglect their duty. They are just as likely to have major accidents such as train or aeroplane crashes, fires and floods, and terrorists may try to strike at a dam or a nuclear power station to induce a leak of radioactive material. Disaster planning should take into account the locality and what may be vulnerable there. This might be an airport, a large chemical works or a nuclear power station.

Co-ordinated planned response

Every local government authority and every local health authority should have plans in place for dealing with such eventualities. They will involve strategic command of hospitals, ambulance, police, fire services and traffic control. There may also be a need for provision of accommodation and of counselling services. An integrated response from all participants (front-line responders, public health and local/regional/national authorities) is essential.

Whilst a single record cannot give a full account of the complicated sequence of events that follows a major disaster, you will find here an overview of:

  • Planning for a disaster.
  • Response to the disaster in the field.
  • Subacute presentations following biological, chemical or radiation exposure.

Major incident management is not something that just happens in response to an event. Since the 1990s there have been multidisciplinary plans in place to deal with emergencies.

The Civil Contingencies Act 2004[3]

This provides a framework for civil protection in the UK. There are two main parts:

  • This sets out the roles and responsibilities for those involved in emergency preparation and response at the local level. It identifies two categories of responders:
    • Category 1 responders - this includes emergency services, local authorities and NHS bodies. They are responsible for planning for emergency situations and putting these plans into action. They are also responsible for liaising with the public and with other responders and for business continuity management (ie keeping the non-affected parts of the community going).
    • Category 2 responders - these include the Health and Safety Executive, transport and utility companies. These tend only to be affected where the incident affects their sector but they will liaise with category 1 responders to provide assistance.
    Category 1 and 2 organisations will come together to form Local Resilience Forums (based on police areas) which will help co-ordination and co-operation between responders at the local level.
  • This allows for the making of temporary special legislation (emergency regulations) to help deal with the most serious of emergencies. The use of emergency powers is a last resort option and planning arrangements at the local level should not assume that emergency powers will be made available.

Originally, the aim was to review the act on a three-yearly basis but, since the act came into being, there have been renewed terror threats. In the light of these, an enhancement programme is being put into place to take into account the evolving situation that the UK faces.

Organising a planned response to a disaster

There are multiple levels of planning, ranging from individual hospital plans through to national protocols. Disaster plans should include:

  • Generic plans.
  • Specific plans (relating to specific emergencies).
  • Plans where there is single vs multilevel agency involvement.
  • Multilevel planning (ie covering more than one level of government).

It is worth noting that there are slight variations in national plans across England, Wales, Scotland and Northern Ireland.

Testing the plan

These plans need to be rehearsed and are continually updated. They are tested with periodic exercises involving all those who would be involved at a strategic level as well as representatives of senior frontline staff, to ascertain that all runs well and to discover any problems that require solutions before the real event:

  • The training exercises may be discussion-based, 'table-top' or 'live'.
  • They help the team to gain familiarity with the equipment and with each other.
  • They are known by code names:
    • 'Exercise Green Goblin II': multi-agency response to a major incident that involved a chemical release (2006).
    • 'Exercise Phoenix': recovery after influenza pandemic (2007).
    • 'Exercise Solent Sunshine': detonation of a radiological dispersion device (2008).

Planning for those indirectly affected

Part of emergency planning (which should also be tested) includes the management and care of those not directly affected by the emergency as casualties, such as bereaved families, those who have lost homes and so on. There will need to be good public communication; not only will people need to know what is happening but also precautions they may need to take, where to obtain more information, how to access emergency services (this may include getting safe drinking water, for example) and so on. Good communication will minimise the impact of the disaster on the affected community. Finally, assistance may be needed from or for voluntary organisations and business communities.


If you wish to be part of the team let this be known to the appropriate authorities (your local Clinical Commissioning Group (CCG) is a good starting point). You will need training, orientation and integration into the team. Just turning up on the occasion is like the thespian or musician who misses rehearsals but expects to be included on the night. If you become a member of a medical response team, you will have to become familiar with the kit bag (this comes with training) and keep up to date with the constantly evolving procedures and equipment. You will also have to be prepared to respond at any time; it may be the middle of the night or the beginning of a Monday morning surgery. If you are interested in training, there are a number of courses you can go on:

  • British Association for Immediate Care (BASIC) courses which provide training to various levels of competencies in medical, trauma, paediatric and obstetric emergencies with a particular emphasis on pre-hospital care and liaison with the various pre-hospital services that may be involved.[4]
  • Courses such as the Emergency Planning Officers course, Diploma in Health Emergency Planning (DipHEP) and the Emergo-Application course.

Even if you do not wish to be part of the emergency response team, a general practice surgery may still be able to offer help by volunteering to take some of the less serious cases away from the hospital. It may not be dramatic but every little helps.

Here you will get a generic overview of the organisation at the scene of a major disaster - eg, a train crash or a factory explosion. Go to next section to find out what to do in the case of chemical, biological, radiological and nuclear (CBRN) incidents.

Assessing the scene

An ambulance is likely to be at the scene at an early stage. If it is a major incident, the crew should not become involved in treating individuals but they need to assess the situation and report back to control. Survivors are better served by an informed and co-ordinated response than by instant treatment of a few on arrival. There will be an Ambulance Incident Officer (AIO) who is the senior crew member who is in charge until a more senior officer arrives. His tasks include:

  • Assessing the scene.
  • Declaring a major incident and giving a situation report (SITREP).
  • Deciding where to locate the Control Point, Casualty Clearing Station (CCS), and Ambulance Parking Point, as well as planning ambulance entry and exit routes.
  • The AIO is in charge of communication with all health service personnel on the scene.
  • The AIO discusses with the chain of command the need for additional support, such as a Medical Incident Officer (MIO) on scene, the Medical Emergency Response Incident Team (MERIT) and additional equipment.

Reporting a major incident

This must go through the appropriate channels so that all necessary personnel and services are informed. Full and relevant information must be gathered. There are two mnemonics to help with this. They are METHANE and CHALETS and the contents are similar:

  • Major incident declared.
  • Exact location.
  • Type of incident - eg, explosion and fire in a tall building, release of gas in the underground system.
  • Hazards - present and potential.
  • Access - routes that are safe to use.
  • Number, type, severity of casualties.
  • Emergency services now present and those required.

  • Casualties - number, type, severity.
  • Hazards present.
  • Access routes that are safe to use.
  • Location.
  • Emergency services present and required.
  • Type of incident, as above.
  • Safety.


By now there may be several ambulances on the scene but the control vehicle is recognised as the one that still displays its flashing lights. The AOI is responsible for and in command of all health service personnel on the site unless an MIO is present. The police and fire service will cordon off the area. No one should enter this area without permission from the appropriate officer.

Arrival at the scene: MERIT

This team (formerly known as the Mobile Medical Team) usually consists of a doctor and a nurse, or two of each. They should stay together unless ordered to do otherwise. Ideally, they should not come from the hospital that will be receiving casualties, as they need all their staff but, in a remote area, this may not be practical. They should arrive equipped with kit bags. These contain limited airway, breathing and circulation equipment. They do not contain antidotes for chemical weapons, or non-emergency drugs such as tetanus vaccine.

When the MERIT arrives at the scene they should report to the MIO whose position will be apparent from a flashing green beacon. If none is present, they should report to the AIO at the ambulance with the flashing blue light. The team will probably be sent to the CCS but may be required to assist with the triage and treatment of entrapped casualties. It is not the role of the doctor or nurse to be involved in search and rescue, counselling victims or commanding ambulance personnel.

Personal safety

The scene of a major incident is a dangerous place. There may be structural instability, fire, smoke or nuclear, chemical or biological hazards. Terrorists sometimes plant secondary devices to kill or injure rescue workers.

A rescue worker who becomes one of the injured is not aiding the problem but contributing to it.

Priority for safety is in the order of self, site, patient. GPs will probably not be involved with work at the scene unless they have specific training. Members of BASICS are an obvious example but they should be known to the organisers and be part of the team.

On site, personal protective equipment (PPE) must be available and worn. This includes helmet, jacket, overalls, protective gloves, boots and ear and eye protection. There should also be personal identification. The Ambulance Safety Officer will refuse entry to the site to anyone who is not properly equipped.

It is worth noting that decontamination is led by the Ambulance Service team and mass decontamination by the Fire and Rescue Service. You can find more detail about decontamination under 'Further reading & references', below.[5] This will also provide you with information regarding safety around specific patient groups (eg, respiratory patients, ionised patients) and various printout masters for recording contacts and events.

Organisation at the scene

The whole area around a major incident will be cordoned off by the police and access controlled.

  • The silver area - the area within the cordon is the silver area. All medical activity within the silver area is directed by the MIOs and AIOs, working together. Doctors are under the command of the MIO and ambulance personnel are under the command of the AIO.
  • The bronze area - an inner area around the incident is termed the bronze area. Medical personnel will only enter the bronze area if instructed to do so by the MIO and if permitted to do so by the service responsible for safety at the scene. This is usually the Fire Service. It is a dangerous area and medical activity within it is limited to:
    • Primary triage.
    • Evacuation of casualties.
    • Treatment of trapped casualties.

A doctor may also be required to certify death. Casualties are evacuated to the CCS that will be close to the scene yet at a safe distance and linked to the ambulance loading point. The CCS is for secondary triage, initial stabilisation and preparation for transportation to hospital.


Triage is a system for sorting casualties into priority for treatment by subsequent teams. It enables limited resources to be deployed efficiently. Treating a less critically ill patient could deny life-saving interventions to others who may die as a result. A form of rapid assessment is required and the triage sieve is usually employed. An experienced operator can perform this in about 20 seconds, so that it is possible to triage many people in a short time. See also the separate Trauma Assessment article.

Priorities are numbered 1 to 3 in descending order of need and are colour-coded as follows:

  • P1: immediate priority. It is those who will die without immediate lifesaving intervention. Colour code red.
  • P2: intermediate priority. They will also need significant interventions but can wait a few hours. Colour code yellow.
  • P3: delayed priority. They will need medical treatment but this can safely be delayed. Colour code green.
  • Dead is a fourth classification and is important to prevent the expenditure of limited resources on those who are beyond help. Colour code black.

Walking wounded are automatically classified as P3. This is related to the motor score on the Glasgow Coma Scale and predicts favourable outcome. Time can be saved in the bronze zone by asking all who can proceed to the CCS unaided to do so and automatically classifying them all as P3. This is a useful technique if the area is hazardous and it is necessary to clear it and move on the injured as soon as possible.

Casualties need to be labelled and the cruciate triage card is useful. It has four arms, coloured red, yellow, green and black and the appropriate arm can be displayed. It also facilitates change of category if required. If nothing else is available, write on the person's forehead. Dead bodies should be left where they are, partly to avoid unproductive use of resources and partly because this may be a scene of crime.

Triage is a dynamic process and represents how a person is now. Attempts to anticipate problems will cause too many to be placed in too high a category, preventing adequate treatment of those who cannot wait. A person with a chest wound may be classified as P2 or P3 but, if a tension pneumothorax develops, this immediately becomes P1. When the tension is relieved, the classification is lowered again.

It is quite common for up to 50% of patients to be triaged into too high a category, competing for limited resources. It is common for children to be placed in too high a category and old people in too low a category.

Coping with numbers

On site
By the time that the CCS is set up there may be adequate resources. As a general rule, advanced life support should not be performed in the bronze zone, as it is very labour intensive and the chance of success is limited. More lives will be saved by attention to others. At the CCS there may be enough staff to enable this to be performed without neglecting others who would benefit from immediate attention.

A&E - the casualties
The first patients to arrive at the hospital A&E department are usually the least severely injured. This is because they are the most mobile and the more severely injured may require stabilisation before moving. Hence, the arrival of a large number of people who are not severely injured may be the trigger for the declaration of an emergency. Valuable resources such as ambulances should not be used to transport those who can use other means including cars, taxis or getting on a bus. Those who arrive in A&E have probably been triaged twice already but they will still require a further triage. A different system is required in hospital from in 'the field'. There is no uniform system but a common classification is resuscitation, major and minor.

Managing the casualty numbers in hospital
The hospital major incident plan can be activated either on the request of the Ambulance Service, or autonomously by the hospital. When a disaster is declared it is necessary to try to gauge the scale of the problem and to make a rough estimate of the number and nature of injuries. If an airliner plunges from the skies there will probably be no casualties, only fatalities:

  • It is common practice for one hospital to be the reception centre for injuries whilst another sends out staff to the scene.
  • The receiving hospital needs all its staff on site.
  • A centre of operations is set up there with clinical and managerial input.
  • The clinical director should be a senior doctor with authority, who is not directly involved in the care of the injured, as he cannot do both jobs simultaneously. Hence, he or she will almost certainly not be the A&E consultant or probably any surgeon.
  • The command and control centre will probably not be in A&E, as it will be extremely busy there.

Careful and systematic assessment of non-critical patients already in hospital for early discharge can be used to make hospital beds available for victims of a mass emergency. This is called reverse triage.

A&E - the non-casualties
There will be the usual flow of patients from unrelated events in A&E. Someone has to deal with them or send them elsewhere. This may be to another hospital or asking GPs to cope.

  • If the system is stretched, patients from unrelated sources need to be put through the same triage procedures as those from the major incident.
  • It is inappropriate to send away someone with a serious medical need just because he or she is not a victim of the major incident.
  • It is still useful to note who was from the incident to help with inquires and also reflection on the adequacy of the operation afterwards.

Other hospital departments
All staff (and not just those skilled in the management of trauma) should report for duty when a hospital declares a major incident.

  • Other patients will still need care when perhaps their usual carers have been called away.
  • Someone may need to take the decision to discharge patients to free beds for new arrivals.
  • Routine admissions must be halted.
  • The extent to which this will need to be done depends on the anticipated number of admissions.
  • There should be a designated area where staff can report to in order to be assigned to their duties.
  • Standards of care must be maintained.

GP involvement
The A&E department will become extremely busy. If very large numbers of casualties are expected, it would be helpful if GP surgeries could help with those who do not require the facilities of a hospital. This will also require cancelling a certain amount of routine work to clear time and space.

Not all major disasters present as such immediately - sometimes it's a case of an emerging picture where the disaster becomes apparent over time (the timeframe depends on the nature of the problem - this could be hours to weeks). Cases may be noted for their:

  • Similar epidemiological features.
  • Geographical grouping.
  • Severity of symptoms or signs.
  • Unusual aetiology given circumstances (eg, a disease not usually seen in the UK in a patient who has no travel or contact history).
  • Poor response to conventional treatment.
  • Unknown aetiology.
When assessing a suspicious case, remember the risk of contamination to yourself, other staff and other patients:
  • Isolate the patient.
  • Use standard personal protection equipment (gloves, gown, mask and, if the patient is coughing or vomiting, eye protection).

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Further reading and references