Upper body cooling during exercise-heat stress wearing the improved toxicological agent protective system for HAZMAT operations.

This study compared endurance in a U.S. Army developmental Occupational Safety and Health Administration Level B personal protective equipment (PPE) system against the toxicological agent protective (TAP) suit, the Army's former standard PPE for Level A and Level B toxic environments. The developmental system consisted of two variations: the improved toxicological agent protective (ITAP) suit with self-contained breathing apparatus (ITAP-SCBA), weight 32 kg, and the ITAP with blower (ITAP-B), weight 21 kg. Both ITAP suits included the personal ice cooling system (PICS). TAP (weight 9.5 kg) had no cooling. It was hypothesized that PICS would effectively cool both ITAP configurations, and endurance in TAP would be limited by heat strain. Eight subjects (six men, two women) attempted three 2-hour treadmill walks (0.89 m/sec, 0% grade, rest/exercise cycles of 10/20 min) at 38 degrees C, 30% relative humidity. Metabolic rate for TAP (222+/-35 W) was significantly less than either ITAP-SCBA (278+/-27 W) or ITAP-B (262+/-24 W) (p<0.05). Endurance time was longer in ITAP-SCBA (85+/-20 min) and ITAP-B (87+/-25 min) than in TAP (46+/-10 min) (p<0.05). Heat storage was greater in TAP (77+/-15 W.m(-2)) than in ITAP-SCBA (51+/-16 W.m(-2)) (p<0.05), which was not different from ITAP-B (59+/-14 W.m(-2)). Sweating rate was greater in TAP (23.5+/-11.7 g/min(1)) than in either ITAP-SCBA (11.1+/-2.9 g/min) or ITAP-B (12.8+/-3.5 g/min) (p<0.05). Endurance in ITAP was nearly twice as long as in PPE with no cooling, even though the PICS, SCBA tanks, and new uniform itself all served to increase metabolic cost over that in TAP. PICS could also be used with civilian Levels A and B PPE increasing work time and worker safety.