What causes most exposure fires?

The correct answer identifies radiation as the primary cause of most exposure fires. Radiation refers to the transfer of heat energy in the form of electromagnetic waves, which can ignite combustible materials at a distance from the heat source. In fire scenarios, radiant heat can travel through the air, and when it strikes flammable objects, it can raise their temperature to the point of ignition without direct contact with the flame. This is particularly relevant in cases where a fire spreads to nearby structures or materials that are not in direct contact with the fire source but are heated by the radiation emitted from it.

Understanding how radiation contributes to the spread of fire is crucial for fire prevention and control strategies. While conduction and convection also play roles in fire spread, particularly in how heat moves through solid materials or as hot gases create upward currents, radiation is often the most significant factor in the context of exposure fires, where distance from the fire impacts the likelihood of ignition.