Responses to repeated days of light work at moderate temperatures in protective clothing

This study assessed workers' ability to sustain work output over four consecutive workdays in encapsulating protective clothing (PC). Six subjects wearing a two-piece PC ensemble cycled at a work rate of 38 W in a 29/22 degrees C (dry/wet bulb) ambient temperature. Work continued until rectal temperature (Tre) reached 38.3 degrees C, or volitional fatigue. Subjects then rested without PC in a 21 degrees C room until Tre reached 38.0 degrees C to simulate micro- or macro-environmental cooling during rest. Work was alternated with rest for four hours total. Contrary to expectations, mean work time did not diminish on succeeding days. Subject responses to the repeated exposures was highly variable and in no case changed significantly (p > .05) from day one to day four. Subjects tolerated well repeated four-hour exposures with controlled elevations in Tre. There was no clear evidence of either increased or decreased tolerance of this work-rest paradigm across days.