Define shelter-in-place and provide a scenario when it is preferred over evacuation.

• A. Shelter-in-place means leaving the area immediately.
• B. Shelter-in-place means staying indoors and sealing openings to reduce exposure; preferred when hazards are external (e.g., chemical plume) and evacuation would pose greater risk.
• C. Shelter-in-place means sheltering in a public building.
• D. Shelter-in-place means opening all windows to ventilate.

Answer: (B)

Shelter-in-place means staying indoors and taking steps to minimize exposure to outside hazards. The goal is to keep hazardous outdoor air from getting inside by closing doors and windows, reducing or turning off ventilation, and sealing gaps. This approach is used when the danger is external—like a chemical plume, wildfire smoke, or radioactive release—and evacuating would expose people to the hazard or create greater risk due to traffic, bottlenecks, or danger on evacuation routes.

A common scenario is a chemical release downwind of a neighborhood. Officials may advise shelter-in-place, so you stay inside, close and seal doors and windows, turn off fans or the HVAC system if safe, and go to an interior room with the fewest outside walls. Stay tuned to official updates until it’s safe to evacuate or until instructed otherwise.

The other ideas don’t fit because leaving the area describes evacuation, not shelter-in-place; shelter-in-place can be done anywhere there is a suitable indoor space, not necessarily a public building; and opening windows to ventilate would let contaminants inside, defeating the purpose of sheltering.