PROTECTIVE CLOTHING AND HEAT-STRESS

The high level of protection required by protective clothing (PPC) sev erely impedes heat exchange by sweat evaporation. As a result work ass ociated with wearing PPC, particularly in hot environments, implies co nsiderable physiological strain and may render workers exhausted in a short time. Current methods of describing evaporative heat exchange wi th PPC are insufficient, will overestimate evaporative heat loss and s hould not be recommended. More reliable measures of the resistance to evaporative heat transfer by PPC should be developed and standardized. Direct measurements of evaporative resistance of PPC may be carried. However, a more promising method appears to be the definition of evapo rative resistance on the basis of the i(cl)-index for the fabric layer s. The i(cl)-index is a permeation efficiency ratio, which in combinat ion with clothing insulation determines the evaporative heat transfer. Current methods should be further developed to account for effects of moisture condensation and microclimate ventilation.