Air-Conditioned Cooling During Consecutive Work-Rest Cycles in the Heat

Area of Science:

• Occupational health and safety
• Environmental physiology
• Thermoregulation

Background:

• Heat stress poses significant risks in occupational settings, particularly during prolonged physical work.
• Effective cooling strategies during rest periods are essential for mitigating heat strain and preventing heat-related illnesses.

Purpose of the Study:

• To evaluate the impact of air-conditioned rest versus hot environment rest on body temperature changes.
• To assess core body temperature fluctuations during repeated work-rest cycles in a hot environment.

Main Methods:

• Ten participants underwent two trials, each with three 45-minute work cycles (walking in 36°C, 40% RH) followed by 15-minute rest periods.
• Rest was conducted either in the hot environment (hot cooling) or in an air-conditioned space (cold cooling).
• Rectal core temperature (T re), mean skin temperature, and mean body temperature were continuously monitored.

Main Results:

• No significant difference in peak rectal core temperature (T re) was found between the hot cooling and cold cooling conditions at the end of the three work-rest cycles.
• This indicates that passive rest in an air-conditioned environment did not provide a superior advantage in reducing peak body temperature compared to resting in the heat.

Conclusions:

• Passive rest in an air-conditioned space does not effectively mitigate peak core body temperature during repeated work-rest cycles in the heat.
• Current occupational safety guidelines may need re-evaluation regarding the efficacy of passive cooling during intermittent heat exposure.