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Cooling efficiency of different air velocities in hot environments.

Kamon E; Goldfuss A; Hodgson JL; Loomis JL; Dukes-Dobos FN
Cincinnati, OH: U.S. Department of Health, Education, and Welfare, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHEW (NIOSH) Publication No. 79-129, 1979 Mar; :1-104
In order to study the effectiveness of increased wind velocity in reducing strain at various ambient conditions, four heat acclimated college students were exposed for 90 minutes to each of two combinations of work heat conditions. In the first condition the metabolic level (M) of 200 kilocalories (kcal) per hour (hr) was maintained with Wet Bulb Globe Temperatures (WBGT) of 28.9, 31.1, 32.8, and 34.4 degrees-C. In the second condition the M was 300kcal/hr with WBGT of 27.2, 28.9, 31.1 and 32.8 degrees. Two additional volunteers were exposed to the second condition for 120 minutes. The various parameters measured included rectal temperature, heart rate, skin temperature, evaporation rate, sweating rate, and work performed. In general the work loads and the ambient conditions selected were not too demanding physiologically. For all practical purposes the rectal temperature and heat rate leveled off during the last 30 minutes of the exposure periods. The skin temperature and evaporation rate did show some differences due to wind velocity, but only for the higher work load where M was 300kcal/hr. The clothing used in this study was a blend of 65 percent polyester and 35 percent combed cotton fibers which may have interfered to some degree with the evaporative cooling due to increased wind velocity. The longer exposure periods did not result in any reduction in the rise of rectal temperatures or heart rates or any increase in skin temperatures due to the increased wind velocities. The authors conclude that while there were differences in the physiological responses for the different WBGT conditions, there were no significant differences due to increased wind velocities under these relatively hot and dry conditions.
NIOSH-Author; Workplace-studies; Outdoors; Temperature-effects; Hot-environments; Humidity; Work-clothing; Physiological-response; Physiological-measurements
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DHEW (NIOSH) Publication No. 79-129
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National Institute for Occupational Safety and Health
Page last reviewed: February 18, 2022
Content source: National Institute for Occupational Safety and Health Education and Information Division