Which method of ventilation involves using mechanical equipment?

Positive pressure ventilation is a method that utilizes mechanical equipment to move air and control the environment within a structure, typically to remove smoke and heat during a firefighting operation. This technique involves the use of fans or blowers to increase the pressure inside the structure, forcing smoke and hot gases out through designated openings. By creating this positive pressure, firefighters can enhance visibility and improve conditions for search and rescue operations while also helping to prevent the backdraft hazard.

In contrast, natural ventilation relies on environmental conditions such as wind and temperature differences to allow fresh air to enter and smoke or hot gases to exit. Negative pressure ventilation involves the use of fans to create a vacuum effect, drawing smoke out of a building rather than pushing air in. Controlled ventilation refers to a combination of techniques that may not necessarily involve mechanical systems, focusing instead on managing airflow for optimal effectiveness. Each of these alternative methods has its own applications and considerations, but it is positive pressure ventilation that distinctly employs mechanical equipment as its primary feature.