Quantification of heat balance during work in three types of asbestos-protective clothing

Three types of protective suits for asbestos removal work were tested in a climatic chamber at two ambient temperatures, 25 degrees and 36 degrees C. Four subjects performed 50 min of bicycle exercise at 90 W dressed in shorts, socks and sneakers (NoPS). The same test was carried out with three different types of asbestos-protective suits worn on top of NoPS. Suits were made of GoreTex (GT), polypropylene (PP) and Tyvek (TYV). At 25 degrees C, responses differed very little between suits and thermal strain was small. At 36 degrees C, strain was least with NoPS. TYV resulted in significantly higher physiological and thermal strain than did PP and GT. Evaporative heat loss was maintained at a similar level with less permeable ensembles, but at the expense of increased skin wetness and sweat rate. Measured values compared favourably with calculated values for skin wetness and sweat rate according to ISO 7933, when resultant, rather than standard, basic data for insulation and evaporative resistance of ensembles were used. Results indicate that differences between suits that may be of little importance at normal room temperature become significant at higher stress levels (increased activity and/or air temperature).