Which statement best describes Positive-Pressure Ventilation (PPV) on the fireground?

Which statement best describes Positive-Pressure Ventilation (PPV) on the fireground?

• A. Negative-pressure ventilation pulls air out of the structure to exhaust smoke.
• B. Natural ventilation relies on openings to move air.
• C. Mechanical exhaust only without intake.
• D. Positive-pressure ventilation pushes fresh air into the structure to improve visibility.

Answer: (D)

Positive-Pressure Ventilation uses a blower to push fresh outdoor air into the structure, creating higher pressure inside than outside. That positive pressure drives smoke, heat, and combustion byproducts out through existing openings or designated exhaust paths, thinning the smoke and lowering the temperature to improve visibility and overall conditions for occupants and crews. This description is the best fit because it states both the mechanism—air is pushed in—and the key effect—smoke is displaced to improve visibility.

The other ideas describe different approaches: pulling air out of the structure is negative-pressure or exhaust ventilation, relying on openings without mechanical input is natural ventilation, and mechanical exhaust only without intake lacks the necessary supply of fresh air to drive out the smoke.