What signs may indicate potential structural collapse in a building?

Visible cracks and sagging or bowing walls are critical signs that may indicate potential structural collapse in a building. These physical manifestations often suggest that the structural integrity of the building is compromised. Cracks can indicate that materials are under stress or have shifted due to an overload or fire damage, while sagging or bowing walls can signal that the load-bearing elements of the structure are failing. Observing these conditions should prompt immediate concern and action, as they are serious indicators that the structure may not be safe for personnel operating within or nearby.

In contrast, green foliage, the presence of firefighters inside, and clear skies above the building do not provide reliable information regarding structural stability and collapse risk. Green foliage may indicate a healthy environment, while firefighters may be inside conducting operations safely under different conditions. A clear sky above does not correlate to structural integrity and might be misleading in assessing the risks associated with a building's physical condition. Understanding these signs is crucial for safety and decision-making during firefighting operations.