Effects of a novel ice-cooling technique on work in protective clothing at28 degrees C, 23 degrees C, and 18 degrees C WBGTs

This study tested a new ice cooling system that permits ice cooling system recharge without personal protective clothing removal. Six male volunteers (22.1 +/- 1.2 years) underwent tests with the new ice cooling system (COOL) and without (NOCL) at a moderate work rate (450 W) in three environments o f 28, 23, and 18 +/- 1 degrees C wet bulb globe temperature. Walks at 28 de grees C were carried out first with NOCL and COOL counterbalanced, then tes t order and environment were counterbalanced. At 28 degrees C, mean work ti me in COOL significantly increased by 37.5 min (188%) over NOCL (p<0.05). A t 23 degrees C mean work time in COOL was significantly increased by 44.3 m in (171%) compared with NOCL (p<0.05). Mean work times at 18 degrees C were not significantly different, although all subjects completed the 120 minut es of work in COOL compared with a mean work time of 109+/-20 min for NOCL. During rest, mean reductions in rectal temperature were significantly grea ter in COOL than NOCL (p<0.05) at 28 and 23 degrees C. Mean heart rate calc ulated for the same point in both treatments was significantly lower for CO OL at 28, 23, and 18 degrees C (p<0.05). Thermal comfort rating was signifi cantly different at 18 and 23 degrees C (p<0.05). This new design seemed to provide comparable cooling to conventional vests and also provides greater practicality for field use. Even in experimental form the suit demonstrate d increased productivity due to extended tolerance time.