A range of different events may result in an evacuation to protect the public from a hazard. However, evacuations should not be undertaken lightly, as they are difficult to organise and carry through effectively. Organisations responding to an event should consider whether there are other options, such as sheltering, which would provide as good or better public protection, and whether the considerable material and social costs of evacuation would be justified by the level of risk. Evacuation can result in considerable stress to evacuees, loss of business, disruption to personal and work routines and a risk of accidents occurring during the process. These factors should be taken into account in deciding whether and when to evacuate.

In deciding whether evacuation is necessary, the organisation co-ordinating the response to the event should take advice from all available sources. However, it must be accepted that, in many cases of emergency evacuation, decisions would have to be taken on the basis of incomplete information and the professional expertise of the people immediately involved.

3.1. Evacuation can happen as a result of a range of different events:

• A sudden event, happening in a specific area – most evacuation situations will fall into this category, including fires, floods and chemical incidents.
• A planned event which creates a danger zone around it, such as a large demolition project.
• A ‘silent’ emergency where responders are unaware of a situation until people begin to self-evacuate in response to a perceived or actual threat, for example in response to civil unrest or threats, or industrial activities which people believe to be posing an unacceptable level of risk.
• A long-term situation where there is a threat of future danger or where long-term exposure to a low-level hazard would be injurious to health, for example where properties are found to be on top of unstable mine workings, or where there is environmental pollution for which no effective remedial action is available.

The first three of these will be responsible for almost all evacuations, although the possibility of the fourth should always be kept in mind.

3.2. Where a response to an event is already underway by the time the need for evacuation becomes apparent, the usual principles of emergency response and of command, control and co-ordination will apply. Information on incident management can be found in ‘Dealing With Disaster’ and ‘A Guide to Emergency Planning in Northern Ireland’ (see Bibliography, Appendix B, for details).

3.3. The lead organisation for the co-ordination of response activities will normally take the decision on whether it is necessary to evacuate. This decision will be based on operational experience and the advice of specialists. Those with information and/or expertise which could be relevant to making a decision to evacuate include:

• The Fire Brigade, who can advise on the possible spread of fire or the effects of chemicals involved in an incident.
• Property owners and operators, especially where hazardous or explosive chemicals are involved.
• Drivers, operators, owners and chemical companies in the event of an incident involving the transport of hazardous materials.
• Army Technical Officers, where explosive devices are involved or old ordnance is discovered.
• The Met Office, which can supply information on wind speed and direction, rainfall etc to help determine the potential spread of pollution, smoke etc.
• The Health and Safety Executive for Northern Ireland and the Industrial Research and Technology Unit, who may have access to chemical information and some knowledge of particular sites, although neither have a statutory emergency response capacity.
• The Geological Survey of Northern Ireland can provide advice on ground conditions (liability to subside etc).
• Public Health doctors, who can access information from national databases and obtain help through contracts with experts on the effects of chemicals on public health.
• Environmental Health Officers.
• Other government and academic organisations with specialist knowledge of pollution, flooding and other hazards.
• Gas suppliers, whether mains or bottled, can advise on safety of their installations and products. This may be especially important if mains gas pipes are disrupted or threatened.

3.4. Which organisations are consulted, and how, will depend on the nature of the hazard and the time available for consultation and analysis of the situation. Ideally, a meeting of all parties with information to contribute should be held and a risk analysis made. However, it is often the case that time and full information are not available and the event response co-ordinator will have to make a decision based on the information available at the time and an informal risk assessment.

3.5. In situations where the danger is a long-term one, there will often be more time to analyse the risks and benefits of evacuation. It may be appropriate to consult people on the level of risk they are willing to tolerate and to provide information to enable them to make their own decision on evacuation.

3.6. In some situations, it may be advised that only a certain part of the population should be evacuated. For example, a fit person in a two-storey property may be able to sit out a short-term flood, while the young and old, and occupiers of single-story properties, would be recommended to evacuate for their own comfort and safety. Similarly, pollution or contamination may affect some groups of people more than others, with children and pregnant women being particularly vulnerable to some hazards.

3.7. Factors which will influence the decision on whether or not to evacuate include:

• Whether buildings would provide protection for the period the hazard is expected to last. In most chemical emergency situations the preferred method of ensuring public safety would be to advise everyone to go indoors, close doors and windows and listen to the media for further information – the ‘Go in-Stay in-Tune in’ approach. Evacuation would only be advised where buildings did not give adequate protection, and there was a reasonable chance of evacuating people without exposing them to unacceptable danger levels. In the past it was considered that an explosive hazard should always lead to evacuation, but experience has shown that in some circumstances it may be safer to retreat to a strong area of a building, such as a stairwell.
• Whether the evacuation can be carried out without exposing people to more danger than if they had stayed indoors. The risk has to be assessed of the event reaching a critical stage, or escalating, while people are in the open and most exposed to danger. Evacuation can itself be a hazardous process. With many people moving at once, there is a danger of crushing or traffic accidents. The old, the young and the infirm may be adversely affected by having to move.
• Whether the evacuation can be carried out without exposing responding staff to an unacceptable degree of danger. Each organisation has a statutory responsibility for the health and safety of its staff. This requires them to assess the risks faced by their staff and to take all possible steps to mitigate them. This may involve ensuring that staff are provided with appropriate protective clothing or deciding that an area poses too great a threat to allow staff to enter.
• Whether a situation currently not requiring evacuation has potential to reach a point where evacuation would be necessary. Foresight permits forward planning, and thus facilitates an effective and safe evacuation. A precautionary evacuation may be considered desirable in order to protect people from escalation of the incident.
• If precautionary evacuation is considered, whether the economic and social cost is justified by circumstances. Evacuation disrupts people’s lives, shuts down businesses and interrupts the delivery of essential services. Moving and accommodating the evacuees is expensive, often to the detriment of budgets for everyday services. If time is available to plan an evacuation, opportunities for minimising the costs should be explored. For example, where the date of the evacuation can be set, a weekend is likely to cause less disruption to business and working lives, but more to personal and family lives.

3.8. The response to the event would normally be co-ordinated by the lead organisation responsible for the function.

3.9. In many cases where the event is unpredicted, the lead organisation will be an emergency service, usually either the Police or Fire Brigade. There is a well-established principle that the Police would normally co-ordinate the interagency response to an incident, with the Fire Brigade having a particular response management role in the event of a fire, chemical accident or entrapment.

3.10. Where the response does not primarily involve the emergency services, as with flooding or some pollution incidents, or if the event is planned, as with controlled demolition, the co-ordinating organisation is likely to be a government department, agency or Non Departmental Public Body (NDPB). In the event of there being no immediately apparent lead organisation for the event, the District Council Chief Executive will consider whether co-ordination would be helpful, and if so, would undertake this function.

3.11. Information on the event would be required for the other functional areas of the evacuation:

Warning and Moving

The lead organisation for the event would play a key role in providing information on the nature of risks, the need to evacuate and the scope of the evacuation. It would normally be best placed to advise on where Rest Centres could be safely situated, for example, away from any danger from rising floodwater, changing wind directions or an escalating incident.

Rest Centre

The lead organisation for the event would also have a role in providing information for Rest Centre staff on the status of the event as it progressed and any specific damage or loss which occurred.

Resettlement, Return and Reconstruction

The lead organisation for the event would also need to provide information relevant to the return of evacuees, including actions required to make the area safe for re-occupation, any remedial action required, such as decontamination of buildings and their contents, chances of recurrence, mitigating actions which could be taken and possible long-term effects.

3.12. Communication, especially in an emergency situation, would often be best met by the event co-ordinator appointing a liaison officer to the overall incident co-ordinator.

Here are some of the questions which the person/organisation co-ordinating the response to an event should consider. Not all questions will be relevant to all situations.

Has this event public safety implications?

Where can more information be obtained?

• Police.
• Fire Brigade, including the hazardous material databases it can access.
• Property owners and operators.
• Vehicle drivers, transport and chemical companies.
• Army Technical Officers.
• Met Office.
• HSE(NI), IRTU.
• Public Health Doctors and other Health Service resources.
• Environmental Health Officers.
• Others.

Can public safety be reasonably assured by methods other than evacuation?

• Sheltering.
• Warnings on avoiding particular areas/behaviours.
• Advice to carry out certain tasks, eg boiling water, sandbagging.
• Making supplies available, eg drinking water, heaters.
• Changing/enhancing the emergency response.

Is there a risk of the event escalating?

• When?
• How far?
• What would be the effects?

Would the safety measures above (if any) still provide adequate protection?

Is evacuation necessary?

• When?
• Everyone, or just some?
• What area is affected/is likely to be affected?

What are the risks to people if they do evacuate? Are these less than the risks from not evacuating?

Can an evacuation be carried through without unacceptable risk to the staff involved in organising and implementing it?

What will be the potential economic and social costs of the evacuation?

What information is needed by organisations involved in other functions within the evacuation?

• Warning and Moving.
• Rest Centres.
• Resettlement, Return and Reconstruction.

How is liaison with the overall co-ordinator to be achieved?