Which type of fire can affect both people and materials directly?

A flash fire is characterized by its rapid development and high intensity, with flames spreading quickly in a combustible atmosphere. This type of fire can affect both people and materials directly due to its immediate and extreme heat, which can cause serious burns or injuries to individuals in its vicinity. The speed at which a flash fire ignites and engulfs areas means that there is often little time to react, increasing the risk of harm.

In contrast, smoldering fires tend to burn slowly and produce low heat and smoke, affecting materials more gradually and posing a lower immediate risk to people in the same way a flash fire does. Class A fires involve ordinary combustibles like wood, paper, and textiles, while Class B fires involve flammable liquids and gases. Although both class types can cause harm to people and materials, they do not share the same rapidity and intensity that defines a flash fire.