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An increasing number of industrial and aerospace environments pose thermal stress problems. Specific instances include the activities of helicopter and other aircrews, airfield ground support crew, fire-fighters, racing drivers, mine workers and blast furnace operatives. There are several possible avenues by which it may be possible to overcome such heat stress, including reducing exposure times, using alternative clothing, reducing metabolic heat load, shielding from any radiative heat source or reducing environmental temperature. These methods on the main are often either impractical or too expensive to realistically be considered. However, instead of concentrating on changing a person’s general environment it has previously been suggested that altering their microclimate, the thermal environment next to their skin, produces better results. Several studies have shown that heat removal by circulating cool water through pipes in close proximity to the skin is an effective method for the alleviation of heat strain (Gold and Zomitzer, 1968; Shvartz, 1971; Shvartz and Benor, 1971; Webb and Annis, 1968; Webb, Annis and Troutman. 1972). Similarly, air-ventilated clothing may also be used for microclimate control (Allen,

Belyavin, Flick and Higgenbottam, 1981; Griffiths and Boyce, 1971), but as reported by Nunneley and Maldonado (1983) cooling by a liquid-conditioned garment (LCG) has many advantages.