What atmospheric temperature measurements must be made and recorded at each operating coal face?

• A. Wet and dry bulb temperature, and the resultant effective temperature
• B. Only ambient temperature
• C. Only wet bulb
• D. Only dry bulb

Answer: (A)

To manage heat exposure at a coal face, you need to know how hot it actually feels, not just the air’s real temperature. The body’s comfort and safety depend on temperature plus humidity and the potential for evaporation, so you take both dry-bulb and wet-bulb readings. The dry-bulb temperature is the true air temperature, while the wet-bulb temperature reflects how much cooling evaporation can occur in the environment (humidity and moisture availability influence this). Using these two measurements you derive the effective temperature, a single index that captures heat stress risk and informs decisions like ventilation adjustments and work-rest schedules.

Relying on ambient temperature alone misses humidity effects, and using only one measurement (dry or wet) leaves out either the actual air temperature or the evaporation potential. Because conditions can vary from face to face—due to ventilation patterns, heat sources, and airflow—you record both readings and the resulting effective temperature at each operating coal face to accurately assess and manage safety.