What does "thermal radiation" indicate in terms of fire and explosion risks?

Thermal radiation signifies the transfer of heat energy from a fire through electromagnetic waves, which can significantly influence fire and explosion risks. The correct choice emphasizes that this heat can ignite nearby combustible materials, thus contributing directly to the potential escalation of a fire or the initiation of an explosion. Understanding thermal radiation is crucial, as it helps in assessing how far heat can reach and what materials may be at risk of ignition if they are in proximity to the fire.

In a fire scenario, thermal radiation can lead to secondary ignitions, where materials that are not in direct contact with the flame can catch fire due to the heat radiated from it. This process highlights the need for appropriate safety measures and distance considerations in environments where flammable materials are present.

The other options do not accurately capture the implications of thermal radiation in fire and explosion scenarios. The cooling effect of a fire, the light emitted, and the total heat released during a chemical reaction each focus on different aspects of fire phenomena, but they do not convey how thermal radiation primarily pertains to the risks associated with igniting nearby materials.