Which two ventilation approaches are commonly used on the fireground, and what is each approach's purpose?

• A. Natural ventilation relies on openings to move air.
• B. Mechanical ventilation uses turbines exclusively.
• C. Positive-pressure ventilation pushes fresh air into the structure to improve visibility; negative-pressure ventilation pulls air to exhaust smoke.
• D. Hydraulic hatch ventilation uses water jets.

Answer: (C)

Controlling airflow to manage smoke, heat, and toxic gases while supporting interior operations is what this item tests. The two ventilation approaches you’ll commonly use on the fireground are positive-pressure ventilation and negative-pressure ventilation.

Positive-pressure ventilation pushes fresh air into the structure with a blower, creating higher pressure inside than outside. That increased pressure helps push smoke and hot gases out through existing exhaust openings, clears the space, improves visibility, and makes it easier and safer for crews to work inside and for potential victims to be located.

Negative-pressure ventilation, on the other hand, uses a fan to pull air out of the building, creating a slight negative pressure inside. This draws smoke and heat toward the exhaust path and out of the structure, reducing smoke density and improving tenable conditions for occupants and firefighters during search and suppression.

Natural ventilation and other concepts exist, but they are less controllable in a fire environment, which is why the active mechanical approaches shown here are the standard on the fireground.