A high-velocity fog stream can be used in firefighting situations to drive heat and smoke ahead of the firefighters in a passageway. This technique should only be used when __________.

Correct Answer: Option A — there is an outlet for the smoke and heat

High-velocity fog streams effectively push heat and smoke, but this technique creates a piston effect. Without a clear outlet for the displaced gases, the heat and smoke will be forced back toward the firefighters, significantly increasing the risk of thermal injury and respiratory distress during the firefighting evolution.