What is meant by "positive pressure ventilation" in firefighting?

Positive pressure ventilation refers to the technique used in firefighting where fans or blowers are employed to force fresh air into a structure. This method effectively pushes out smoke and heat, creating a safer environment for firefighters and improving visibility inside the structure. The introduction of fresh air helps to lower the temperature and clear harmful smoke, thereby facilitating rescue and extinguishment operations.

This tactic is particularly useful in instances of fire where it is important to control the atmosphere within the structure. By pressurizing the space, firefighters can help to push the smoke out of openings like windows or doors, thereby improving conditions for both the occupants who may be trapped and the firefighters operating inside.