A sudden, usually unexpected event that does or could do harm to people, resources, property, or the environment. Emergencies can range from localized events that affect a single office in a building, to human, natural or technological events that damage, or threaten to damage, local operations. An emergency could cause the temporary evacuation of personnel or the permanent displacement of personnel and equipment from the site to a new operating location environment.

The distinction between a widespread versus a localized emergency event is based on an assessment of the impact of an event on a department, business unit or facility operations. Normally, if an event impacts a significant number of employees or could force the relocation of a significant number of employees, the event is considered widespread. Localized events are usually limited to smaller or isolated areas of a facility, such as a department or business unit.