What is spalling in relation to firefighting safety?

Spalling refers to the chipping or pitting of surfaces, particularly in materials such as concrete or masonry, due to extreme heat exposure during a fire. When these materials are subjected to high temperatures, the moisture within them can vaporize and create pressure that causes pieces of the material to break off. This not only compromises the structural integrity of the building but also poses a significant safety risk to firefighters and other responders. Understanding spalling is crucial for firefighting safety since it can lead to unexpected material failures during rescue operations or firefighting efforts, increasing the risk of injury.

The other choices do not accurately capture the essence of spalling; they focus on different phenomena related to firefighting but do not pertain to the specific physical degradation of materials that spalling describes.