What is the recommended action regarding HVAC systems to limit smoke spread during a fire?

• A. Keep HVAC systems on to maintain pressure
• B. Vent dampers wide open to vent smoke
• C. Disable all electrical power to the building
• D. When properly shut down or managed, HVAC systems help limit smoke spread and support ventilation

Answer: (D)

Smoke moves with the air inside a building, so how the HVAC system is controlled during a fire can dramatically affect where the smoke goes. Keeping the system running or opening dampers can push smoke into areas that should stay clear, complicating evacuation and firefighting efforts. The recommended action is to shut down or properly manage the HVAC so air doesn’t circulate through unburned parts of the building. This isolation limits cross‑contamination, helps keep escape routes clearer, and can even support ventilation by directing smoke toward designated exhaust paths rather than through occupiable spaces. In short, controlled shutdown or correct zoning of the system reduces smoke spread and aids the overall response.