What is the function of negative-pressure ventilation?

Negative-pressure ventilation is primarily used to eliminate smoke, heat, and toxic gases from a structure during fire operations. The method involves the strategic use of fans to create a lower pressure inside the building compared to the outside atmosphere. As a result, outside air is drawn into the building through openings, which effectively pulls out the heated air and smoke.

This technique is crucial in firefighting as it enhances visibility for firefighters and helps reduce the spread of fire by removing hot gases and smoke that could feed the fire. Drawing smoke and heat out not only improves safety for personnel working within the structure but also aids in rescuing victims trapped inside. It also assists in controlling the environment for more effective firefighting efforts.

In contrast, other functions mentioned in the options pertain to different types of ventilation strategies. Pushing contaminated air out or creating a positive airflow does not accurately depict the mechanics of negative-pressure ventilation. Similarly, increasing the oxygen supply to a fire runs counter to standard firefighting protocols aimed at controlling flames by limiting oxygen.