Evaluation of a Carbon Dioxide Personal Cooling Device for Workers in Hot Environments

This study tested the effectiveness of a carbon dioxide cooling device in reducing heat strain for workers in a hot and humid environment. Ten participants completed two trials in an environment of 30 degrees C WBGT (75% relative humidity) with a novel liquid carbon dioxide cooling shirt (CC) or no cooling (NC) in a randomized order. Mean time-weighted workload for each individual equaled 465 W (400 Kcals center dot h-1). In the CC condition, the work time was significantly increased by 32% (97 +/- 36 min) compared with NC (74 +/- 26 min) (p 0.05). There was no significant difference in mean skin temperature over the trials. Rectal temperature (Tre) was significantly different after 50 min (p 0.05). Mean heart rate, the delta Tre increase rate, and heat storage at 55 min (last point with n = 8) were significantly lower in CC (p 0.05). Overall heat storage was 54 +/- 41 W and 72 +/- 40 W for CC and NC, respectively (p 0.05). Participants also indicated favorable subjective responses for CC vs. NC (p 0.05). These findings suggest that this novel cooling device would effectively attenuate heat strain and increase work productivity for personnel working in a hot and humid environment. Practical aspects of use such as cost, convenience, weight, cooling duration, and rise in ambient CO2 concentration in confined spaces must also be considered.