According to research by the U.S. Army, after how many hours of heat stress does vigilant task performance start to degrade?

The research by the U.S. Army indicates that after 2 to 3 hours of heat stress, vigilant task performance begins to degrade. This timeframe is significant because it highlights the impact of prolonged exposure to high temperatures on cognitive function and physical performance. The body’s ability to manage heat, maintain core temperature, and ensure adequate blood flow can diminish after this period, leading to increased fatigue, reduced alertness, and impaired decision-making. Understanding this threshold is crucial for those working in high-heat environments, such as firefighters, to implement proper hydration, rest breaks, and monitoring protocols to maintain performance and safety.