Secondary fires can occur because of which of the following?

• A. Heat
• B. Sparks
• C. Vapors
• D. All of the above

Answer: (D)

Secondary fires happen when energy from the initial blaze creates conditions that ignite other materials away from where the fire started. Heat can keep nearby fuels at their ignition temperature even after the main flames are gone, sparking a new flame on a adjacent object. Sparks can travel and land on combustible materials, starting a fresh fire some distance from the original source. Vapors or flammable liquids can vent, travel through spaces, mix with air, and ignite if they encounter a heat source or spark. Because each of these pathways can independently cause ignition outside the primary fire, the best choice is the one that includes all three factors.