Heat balance when wearing protective clothing

This issue of the Annals of Occupational Hygiene is dedicated to the topic of heat stress evaluation. For this evaluation, several evaluation programs and international standards are available. In order to understand the reas oning and underlying theory behind these programs and standards, a basic kn owledge of heat exchange processes between workers and their environment is needed. This paper provides an overview of the relevant heat er;change pro cesses, and defines the relevant parameters (air and radiant temperature, h umidity, wind speed, metabolic heat production and clothing insulation). Fu rther it presents in more detail the relation between clothing material pro perties and properties of clothing ensembles made from those materials, The effects of clothing design, clothing fit, and clothing air permeability ar e discussed, and finally an overview; of methods for the determination of c lothing heat and vapour resistance is given. (C) 1999 British Occupational Hygiene Society. Published by Elsevier Science Ltd. All rights reserved.