Which of the following is NOT considered a means of ventilation?

Vacuum is not considered a means of ventilation in the context of fire tactics and strategy. Ventilation refers to the methods used to introduce fresh air into a structure and remove heat, smoke, or gases, which is crucial during firefighting operations to improve visibility and reduce the risk of flashover.

Natural ventilation utilizes natural forces, such as wind or temperature differences, to circulate air. Mechanical ventilation involves the use of fans or blowers to enhance the airflow inside a building, actively pushing smoke and heat out. Controlled ventilation combines aspects of both, often using mechanical means to manage the air movement in a way that is strategically beneficial, such as creating a safer environment for firefighters and improving conditions for victims.

In contrast, a vacuum does not introduce fresh air; instead, it typically involves the removal of air (and its associated pressure) from an area, which is fundamentally different from the processes involved in ventilation. This distinction highlights why vacuum is not categorized as a means of ventilation within firefighting operations.