Which of the following is considered a physical health hazard?

Fire and explosions are classified as physical health hazards because they pose immediate and serious risks to human safety and health through physical means. These dangers can lead to burns, injuries, or fatalities due to fire hazards or explosions in the workplace. Understanding that these hazards can create dangerous conditions, such as uncontrollable flames or shockwaves, is vital for maintaining safety.

In contrast, while exposure to toxic chemicals is a significant hazard, it primarily affects health through chemical means rather than physical. Moving machinery parts can lead to injuries as well, but they are not inherently considered physical health hazards in the same context as fire and explosions. Noise pollution can result in long-term health effects, primarily auditory, but it doesn't create immediate physical danger like fire and explosions do. Thus, the immediacy and physical nature of hazards posed by fire and explosions categorize them distinctly as physical health hazards.