An emergency is a situation that poses an immediate risk to health, life, property or environment. Most emergencies require urgent intervention to prevent a worsening of the situation, although in some situations, mitigation may not be possible and agencies may only be able to offer palliative care for the aftermath.
While some emergencies are self-evident (such as a natural disaster that threatens many lives), many smaller incidents require the subjective opinion of an observer (or affected party) in order to decide whether it qualifies as an emergency.
The precise definition of an emergency, the agencies involved and the procedures used, vary by jurisdiction, and this is usually set by the government, whose agencies (emergency services) are responsible for emergency planning and management.
Defining an emergency 
In order to be defined as an emergency, the incident should be one of the following:
- Immediately threatening to life, health, property or environment.
- Have already caused loss of life, health detriments, property damage or environmental damage
- Have a high probability of escalating to cause immediate danger to life, health, property or environment
In the United States, it is generally a requirement in most states that there must be a notice be printed in each telephone book requiring that, if a person requests the use of a telephone line (such as a party line) because of an emergency, the other person must relinquish use of said line immediately, if their use is not also in the nature of an emergency. An emergency is also typically defined by those state statutes as "a condition where life, health or property is in jeopardy, and the prompt summoning of aid is essential."
Whilst most emergency services agree on protecting human health, life and property, the environmental impacts are not considered sufficiently important by some agencies. This also extends to areas such as animal welfare, where some emergency organisations cover this element through the 'property' definition, where animals owned by a person are threatened (although this does not cover wild animals). This means that some agencies will not mount an 'emergency' response where it endangers wild animals or environment, although others will respond to such incidents (such as oil spills at sea that threaten marine life). The attitude of the agencies involved is likely to reflect the predominant opinion of the government of the area.
Types of emergency 
Dangers to life 
Many emergencies cause an immediate danger to the life of people involved. This can range from emergencies affecting a single person, such as the entire range of medical emergencies including heart attacks, strokes, and trauma, to incidents that affect large numbers of people such as natural disasters including tornadoes, hurricanes, floods, and mudslides.
Most agencies consider these to be the highest priority of emergency, which follows the general school of thought that nothing is more important than human life.
Dangers to health 
Some emergencies are not immediately threatening to life, but might have serious implications for the continued health and well-being of a person or persons (although a health emergency can subsequently escalate to be threatening to life).
The causes of a 'health' emergency are often very similar to the causes of an emergency threatening to life, which includes medical emergencies and natural disasters, although the range of incidents that can be categorised here is far greater than those that cause a danger to life (such as broken limbs, which do not usually cause death, but immediate intervention is required if the person is to recover properly)
Dangers to property 
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Other emergencies do not threaten any people, but do threaten peoples' property. An example of this would be a fire in a warehouse that has been evacuated. The situation is treated as an emergency as the fire may spread to other buildings, or may cause sufficient damage to make the business unable to continue (affecting livelihood of the employees).
Many agencies categorise property emergency as the lowest priority, and may not take as many risks in dealing with it. For instance, firefighters are unlikely to enter a burning building they know to be empty, as the risk is unjustified, but are more likely to enter a building where people are reported as trapped, unless they believe they can stop the spread of the fire, or "save" the building.
Dangers to the environment 
|This section does not cite any references or sources. (July 2007)|
Some emergencies do not immediately endanger life, health or property, but do affect the natural environment and creatures living within it. Not all agencies consider this to be a genuine emergency, but it can have far reaching effects on animals and the long term condition of the land. Examples would include forest fires and marine oil spills.
Systems of classifying emergencies 
Agencies across the world have different systems for classifying incidents, but all of them serve to help them allocate finite resource, by prioritising between different emergencies.
The first stage in any classification is likely to be defining whether the incident qualifies as an emergency, and consequently if it warrants an emergency response. Some agencies may still respond to non-emergency calls, depending on their remit and availability of resource. An example of this would be a fire department responding to help retrieve a cat from a tree, where no life, health or property is immediately at risk.
Following this, many agencies assign a sub-classification to the emergency, prioritising incidents that have the most potential for risk to life, health or property (in that order). For instance, many ambulance services use a system called the Advanced Medical Priority Dispatch System (AMPDS) or a similar solution. The AMPDS categorises all calls to the ambulance service using it as either 'A' category (immediately life threatening), 'B' Category (immediately health threatening) or 'C' category (non-emergency call that still requires a response). Some services have a fourth category, where they believe that no response is required after clinical questions are asked.
Another system for prioritizing medical calls is known as Emergency Medical Dispatch (EMD). Jurisdictions that use EMD typically assign a code of "alpha" (low priority), "bravo" (medium priority), "charlie" (requiring advanced life support), delta (high priority, requiring advanced life support) or "echo" (maximum possible priority, e.g., witnessed cardiac arrests) to each inbound request for service; these codes are then used to determine the appropriate level of response.
Other systems (especially as regards major incidents) use objective measures to direct resource. Two such systems are SAD CHALET and ETHANE, which are both mnemonics to help emergency services staff classify incidents, and direct resource. Each of these acronyms helps ascertain the number of casualties (usually including the number of dead and number of non-injured people involved), how the incident has occurred, and what emergency services are required.
Agencies involved in dealing with emergencies 
Most developed countries have a number of emergency services operating within them, whose purpose is to provide assistance in dealing with any emergency. They are often government operated, paid for from tax revenue as a public service, but in some cases, they may be private companies, responding to emergencies in return for payment, or they may be voluntary organisations, providing the assistance from funds raised from donations.
Most developed countries operate three core emergency services:
- Police – who deal with security of person and property, which can cover all three categories of emergency. They may also deal with punishment of those who cause an emergency through their actions.
- Fire service – who deal with potentially harmful fires, but also often rescue operations such as dealing with road traffic collisions. Their actions help to prevent loss of life, damage to health and damage to or loss of property.
- Emergency Medical Service (Ambulance / Paramedic service) – These services attempt to reduce loss of life or damage to health. This service is likely to be decisive in attempts to prevent loss of life and damage to health. In some areas "Emergency Medical Service" is abbreviated to simply EMS.
In some countries or regions, two or more of these services may be provided by the same agency (e.g. the fire service providing emergency medical cover), and under different conditions (e.g. publicly funded fire service and police, but a private ambulance service)
There may also be a number of secondary emergency services, which may be a part of one of the core agencies, or may be separate entities who assist the main agencies. This can include services providing specialist rescue (such as mountain rescue or mine rescue), bomb disposal or search and rescue.
Summoning emergency services 
Most countries have an emergency telephone number, also known as the universal emergency number, which can be used to summon the emergency services to any incident. This number varies from country to country (and in some cases by region within a country), but in most cases, they are in a short number format, such as 911 (United States), 999 (United Kingdom), 112 (Europe) and 000 (Australia).
The majority of mobile phones will also dial the emergency services, even if the phone keyboard is locked, or if the phone has an expired or missing SIM card, although the provision of this service varies by country and network.
Civil emergency services 
In addition to those services provided specifically for emergencies, there may be a number of agencies who provide an emergency service as an incidental part of their normal 'day job' provision. This can include public utility workers, such as in provision of electricity or gas, who may be required to respond quickly, as both utilities have a large potential to cause danger to life, health and property if there is an infrastructure failure.
Emergency action principles (EAP) 
Emergency action principles are key 'rules' that guide the actions of rescuers and potential rescuers. Because of the inherent nature of emergencies, no two are likely to be the same, so emergency action principles help to guide rescuers at incidents, by sticking to some basic tenets.
The adherence to (and contents of) the principles by would be rescuers varies widely based on the training the people involved in emergency have received, the support available from emergency services (and the time it will take to arrive) and the emergency itself.
Key emergency principle 
The reason that an assessment for danger is given such high priority is that it is core to emergency management that rescuers do not become secondary victims of any incident, as this creates a further emergency that must be dealt with.
A typical assessment for danger would involve observation of the surroundings, starting with the cause of the accident (e.g. a falling object) and expanding outwards to include any situational hazards (e.g. fast moving traffic) and history or secondary information given by witnesses, bystanders or the emergency services (e.g. an attacker still waiting nearby).
Once a primary danger assessment has been complete, this should not end the system of checking for danger, but should inform all other parts of the process.
If at any time the risk from any hazard poses a significant danger (as a factor of likelihood and seriousness) to the rescuer, they should consider whether they should approach the scene (or leave the scene if appropriate).
Managing an emergency 
There are many protocols emergency services apply in an emergency, which usually start with planning before an emergency occurs. One commonly used system for demonstrating the phases is shown here on the right.
The planning phase starts at preparedness, where the agencies decide on how they will respond to a given incident or set of circumstances. This should ideally include lines of command and control, and division of activities between agencies. This avoids potentially negative situations such as three separate agencies all starting an official rest centre for victims of a disaster.
Following an emergency occurring, the agencies then move to a response phase, where they execute their plans, and may end up improvising some areas of their response (due to gaps in the planning phase, which are inevitable due to the individual nature of most incidents).
Agencies may then be involved in recovery following the incident, where they assist in the clear up from the incident, or help the people involved overcome their mental trauma.
The final phase in the circle is mitigation, which involves taking steps to ensure no re-occurrence is possible, or putting additional plans in place to ensure less damage is done. This should feed back in to the preparedness stage, with updated plans in place to deal with future emergencies, thus completing the circle.
State of emergency 
In the event of a major incident, such as civil unrest or a major disaster, many governments maintain the right to declare a state of emergency, which gives them extensive powers over the daily lives of their citizens, and may include temporary curtailment on certain civil rights, including the right to trial (for instance to discourage looting of an evacuated area, a shoot on sight policy may be in force)
Personal emergencies 
Some people believe they have an emergency in a situation that does not pose a risk to life, physical health, or property. In these instances, some people feel entitled to an emergency response—a view emergencies agencies may not share.
Some of these cases may be genuine emergencies if they threaten the mental health and well-being of the person involved, but many agencies do not recognise this as valid. This is more likely to be dealt with by social services or a physician than by the traditional emergency service agencies.
See also 
|Look up emergency in Wiktionary, the free dictionary.|
ERWS - Emergency Rescue World Society : www.erws.org
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- Some examples of state statutes defining emergency for this purpose: California Penal Code, Sec. 384;
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