Perspectives in microclimate cooling involving protective clothing in hot environments

Abstract The effectiveness of microclimate cooling systems in alleviating the thermal burden imposed upon soldiers by the wearing of chemical protective clothing under varying environmental conditions has been examined in a series of studies conducted by the U.S. Army Research Institute of Environmental Medicine on the copper manikin, in the climatic chambers and in the field. Liquid-cooled undergarments (LCU) and air-cooled vests (ACV) were tested under environmental conditions from 29°C, 85% rh to 52°C, 25% rh. These parameters were chosen to simulate conditions which may be encountered in either armored vehicles, or in desert or tropic climates. We have reviewed seven studies using LCU (including two ice-cooled vests) and six studies using ACV. LCU tests investigated the effect on cooling when the proportion of total skin surface covered by the LCU was varied. ACV tests examined the effects on cooling during different combinations of air temperature, humidity and air flow rates. Additionally, these combinations were tested at low and moderate metabolic rates. The findings from these LCU and ACV studies demonstrate that (a) cooling can be increased with a greater body surface coverage by a LCU, and (b) evaporative cooling with an ACV is enhanced at low metabolic rates with optimal combinations of air flow rates and dry bulb/dew point temperatures, resulting in the extension of tolerance time. The application of these findings from military to industrial work situations is apparent.

[1]  K. Pandolf.  Effects of physical training and cardiorespiratory physical fitness on exercise-heat tolerance: recent observations. , 1979, Medicine and science in sports.

[2]  Richard R. Gonzalez,et al.  Heat exchange during upper- and lower-body exercise , 1984 .

[3]  K B Pandolf,et al.  Auxiliary cooling: comparison of air-cooled vs. water-cooled vests in hot-dry and hot-wet environments. , 1982, Aviation, space, and environmental medicine.

[4]  R F Goldman,et al.  Increased energy cost with multiple clothing layers. , 1972, Journal of applied physiology.

[5]  G. F. Fonseca.  Effectiveness of Four Water Cooled Undergarments and a Water Cooled Cap in Reducing Heat Stress , 1975 .

[6]  J R Breckenridge,et al.  Heat stress in the cockpit of the AH-1G hueycobra helicopter. , 1970, Aerospace medicine.

[7]  N A Pimental,et al.  Effectiveness of an air-cooled vest using selected air temperature and humidity combinations. , 1987, Aviation, space, and environmental medicine.

[8]  Effectiveness of an Air-Cooled Vest in Reducing Heat Stress of Soldiers in Chemical Protective Clothing, , 1985 .

[9]  K B Pandolf,et al.  Prediction modeling of physiological responses and human performance in the heat. , 1986, Computers in biology and medicine.

[10]  E Shvartz,et al.  Efficiency and effectiveness of different water cooled suits--a review. , 1972, Aerospace medicine.

[11]  K B Pandolf,et al.  Mechanisms of thermal acclimation to exercise and heat. , 1974, Journal of applied physiology.

[12]  Ralph F. Goldman,et al.  Thermal Stress Evaluation of the Mechanized Infantry Combat Vehicle (MICV-XM-723). , 1976 .

[13]  S Konz,et al.  Personal cooling with dry ice. , 1974, American Industrial Hygiene Association journal.

[14]  Stephen R. Muza,et al.  Effectiveness of an Air Cooled Vest Using Selected Air Temperature, Humidity and Air Flow Rate, Combinations , 1987 .

[15]  R F GOLDMAN.  Tolerance time for work in the heat when wearing CBR protective clothing. , 1963, Military medicine.

[16]  Comparison of Air Shower and Vest Auxiliary Cooling during Simulated Tank Operations in the Heat , 1983 .

[17]  M. Sawka,et al.  Influence of hydration level and body fluids on exercise performance in the heat. , 1984, JAMA.

[18]  Richard R. Gonzalez,et al.  Chemical warfare protective clothing: identification of performance limitations and their possible solution , 1987 .

[19]  K B Pandolf,et al.  Cooling different body surfaces during upper and lower body exercise. , 1987, Journal of applied physiology.