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

Abstract

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°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· 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 (T _re ) was significantly different after 50 min (p < 0.05). Mean heart rate, the delta T _re 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.

Keywords:

• heat stress
• heat tolerance
• personal cooling
• thermoregulation

ACKNOWLEDGMENT

This study was supported by a grant from the Kimberly-Clark Corporation. The authors are in no way affiliated with Porticool, Inc. or Kimberly-Clark. We thank all the participants for their participation in this investigation.

Notes

^A Significantly different from NC (p < 0.05).

^A Significantly different from NC (p < 0.05).

^A Significantly different from NC (p < 0.05).

^A Current study.