Abstract
The use of cooling garments in conjunction with fully encapsulating suits offers the potential for reducing the heat strain for workers at hazardous waste sites and chemical emergencies. This study examined the use of ice- and Freon®-based cooling garments during exercise in the heat while wearing a U.S. Coast Guard chemical response suit (CRS), a fully encapsulating, Telfon®-coatted, Nomex® suit. Responses of nine healthy men (mean age 28.8 yr) were measured during moderate exercise at 30% of their maximal oxygen consumption in an environmental chamber maintained at 33.9°C (93°F) and 82% relative humidity. The four randomly assigned experimental conditions were (1) the CONTROL, consisting of a self-contained breathing apparatus (SCBA) worn in conjunction with shorts, shirt, helmet, and shoes; (2) the CRS, consisting of the Coast Guard CRS worn with shorts, shirt, SCBA, helmet, gloves, and boots; (3) the ICE, which was identical to the CRS ensemble, with the addition of an ice and water cooling system; and (4) the FREON, which was also identical to the CRS ensemble, with the addition of a Freon-based cooling system. To the authors’ knowledge, this paper is the first to quantify and compare a Freon-based system with a circulating ice water system. The subjects performed repeated rest/work intervals for 45 min, followed by a 10-min recovery period. Measured physiological responses, including heart rate, skin, rectal, and axillary temperatures, were recorded at 1-min intervals during the tests. The results from this study indicate statistically significant reductions in mean skin temperature and heart rate (p<0.05) in the trials where subjects wore the cooling garments. Significant differences were also seen in lower weight loss and shorter rectal temperature recovery time, indicating a physiological benefit from wearing cooling systems, despite their added weight. Under the conditions of this study, however, neither cooling system fully demonstrated an advantage over the other system.