Emergency evacuation is an immediate egress or escape of people away from an area that contains an imminent threat, an ongoing threat or a hazard to lives or property.
Examples range from the small-scale evacuation of a building due to a storm or fire to the large-scale evacuation of a city because of a flood, bombardment or approaching weather system, especially a tropical cyclone. In situations involving hazardous materials or possible contamination, evacuees may be decontaminated prior to being transported out of the contaminated area. Evacuation planning is an important aspect to mitigat the impact of disasters on humans. Today there many evacuation models to simulate this process for small-scale and large-scale situations.