Introducing fresh air into a compartment fire by opening an exterior opening is most likely to do what, if the opening is not coordinated with suppression?

• A. Decrease heat release rate.
• B. Increase heat release rate due to a new flow path.
• C. Stop pyrolysis.
• D. Reduce fuel availability.

Answer: (B)

Opening an exterior opening changes the airflow through the structure, creating a new flow path that brings in fresh air and allows hot gases to escape. In a compartment fire, this additional oxygen can drive faster and more complete combustion, increasing the heat release rate. If ventilation isn’t coordinated with suppression, the fire can grow more rapidly, intensifying flames and temperatures and making it harder to control or contain.

Ventilation won’t decrease heat release, stop pyrolysis, or reduce fuel availability by itself. Those outcomes would require removing heat, restricting oxygen, or removing fuels—conditions not achieved simply by opening an exterior vent.