Heat strain and hydration status of surface mine blast crew workers

Dehydration and symptoms of heat illness are common among the surface mining workforce. This investigation aimed to determine whether heat strain and hydration status exceeded recommended limits.

Fifteen blast crew personnel operating in the tropics were monitored across a 12-hour shift. Heart rate, core body temperature, and urine-specific gravity were continuously recorded. Participants self-reported fluid consumption and completed a heat illness symptom inventory.

Core body temperature averaged 37.46 ± 0.13°C, with the group maximum 37.98 ± 0.19°C. Mean urine-specific gravity was 1.024 ± 0.007, with 78.6% of samples 1.020 or more. Seventy-three percent of workers reported at least one symptom of heat illness during the shift.

Core body temperature remained within the recommended limits; however, more than 80% of workers were dehydrated before commencing the shift, and tended to remain so for the duration.