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COMPARISON OF MICROENVIRONMENT PRODUCED BY GOVERNMENT ISSUE PERSONAL PROTECTIVE EQUIPMENT

Abstract

J.A. Sol, J.W. Domitrovich, & C.L. Dumke

University of Montana, Missoula, MT

The effects of protective equipment on thermoregulation and performance have been studied in some occupational and recreational settings. Personal Protective Equipment is essential for US Forest Service and Military employees in the field and the risk of a heat-related illness may be affected by the clothing protecting them. A balance of protection and heat permeability is essential during tasks associated with the occupations mentioned. PURPOSE: To compare two types of Government Issue personal protective equipment (PPE) in the heat during submaximal exercise. METHODS: Eight male subjects (Age: 22.3±3.9 years, weight: 73.0±10.7kg, VO2 Peak: 60.2±7.3 ml/kg/min) participated in three random-order trials in a 34.0°C heat chamber. Subjects completed three consecutive rounds of walking at 3.0 mph, 5%grade for a period of 50 minutes followed by a 10 minute break in each trial. The US Forest Service PPE trial (FS) consisted of subjects wearing standard issue Nomex long sleeve shirt and pants. The US Military Battle Dress Uniform trial (BDU) consisted of subjects wearing standard issue BDU uniform. The control trial (CT) consisted of subjects wearing shorts as well as a 100% cotton t-shirt, leather gloves and hard hat; all of which were worn during all three trials. Body weight, blood hematocrit and serum, and specific gravity of urine were analyzed pre- and post-trial. Core temperature was monitored via oral sensor pill consumed the night before the trial. Skin temperature (left triceps, left pectoral, left femoral, and left lateral gastrocnemius) was monitored throughout trials. Relative humidity (RH) of microenvironment created inside PPE was monitored at the same four sites. Heart rate, RPE, Thermal Comfort, and Perceived Sweat Rate were recorded every 10 minutes of the trial. RESULTS: There was no significant difference between the FS and BDU trials observed in core temperature, heart rate, PSI, and combined skin temperature. The data suggested a difference in perceived exertion between hours 2 and 3 compared to hour 1 in the FS trial (Hour 1 = 9, Hour 2 = 12, Hour 3 = 14). While in the BDU trial, the data suggested a continual increase in RPE in relation to time. There was a significant difference between FS and BDU in RH at the left lateral gastrocnemius throughout the trial (56.8 ± 7.6% vs 62.6 ± 8.8%; p=0.025but not in combined RH. (61.8 ± 9.6% vs 63.5 ± 9.6%; p=0.057). CONCLUSION: There was no significant difference observed between the two uniforms across a multitude of factors during submaximal exercise. The data did suggest an increased RH in BDU microenvironment compared to FS which could relate to an increased demand in thermoregulatory function but no conclusions can be asserted. Our study had a relatively low number of participants so inferences could be better defined with further laboratory trials.

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