PHEL curves indicate what aspect of workplace conditions?

• A. Applicable stay times for different amounts of work load conditions
• B. Humidity levels
• C. Core body temperature
• D. Wind speed

Answer: (A)

PHEL curves map how long a person can stay performing a task at different workload levels before reaching a safe physiological limit. They translate how hard the work is into maximum allowable exposure time, guiding breaks, pacing, and task planning to prevent heat strain, fatigue, or overexertion. As the workload increases, the permissible stay time decreases, and lighter work allows longer durations. Humidity, wind speed, or core body temperature aren’t the measures the curve directly provides; those factors influence the curve, but the curve’s purpose is to show the stay time corresponding to different workloads.