Apart from the type of emergency, several key factors affect the decision on whether to evacuate or shelter in place:
- Time factors: The amount of time available before the emergency impacts the area influences the choice. If there is sufficient warning, evacuation may be feasible; if not, shelter-in-place might be safer
- Meteorological conditions: Weather conditions affect the movement and control of hazards (e.g., wind direction for chemical spills) and the feasibility of evacuation routes
- Communication capabilities: The ability to effectively communicate with the public and emergency responders before, during, and after the event is critical for implementing evacuation or shelter-in-place orders
- Response resources and capabilities: The capacity of emergency organizations to implement, monitor, and manage protective actions influences the decision
- Geographic and jurisdictional factors: The size, location, and resources of the affected area and neighboring jurisdictions impact planning and execution of evacuation or sheltering
- Population characteristics: Considerations include accessibility needs, presence of children or unaccompanied minors, and individuals with functional needs requiring special accommodations
- Safety and infrastructure: The structural integrity and safety of shelters, transportation routes, and evacuation assembly points are evaluated, especially in hazards like hurricanes or floods
- Legal authorities: Jurisdictions must consider their legal powers and regulations regarding issuing evacuation or shelter-in-place orders
- Community lifelines: The impact on critical services such as safety, food, water, health, energy, communication, and transportation informs decisions
- Incident specifics: Whether the event is a no-notice or notice event, its scale, and duration influence whether shelter-in-place or evacuation is more appropriate
In summary, the decision to evacuate or shelter in place depends on a complex interplay of timing, hazard behavior, communication, resources, population needs, infrastructure safety, legal authority, and incident characteristics beyond just the emergency type
