HEAT INDUCED HYPERVENTILATION AND THE PROTECTIVE MASK

The impairment in the performance of men wearing the protective clothing was determined by measuring the respiratory and thermal responses of the subjects walking on a treadmill at 3 mph, zero grade at 21 and 40 C and 10 mm Hg vapor pressure. The major cause of the discomfort was found to be thermo- regulatory in nature. The M6 hood added considerably to the heat stress of the subjects. Similarly, as compared to subjects with the heads kept uncovered, wearing the M-17 protective mask also resulted in greater discomfort in the heat. Since a high body temperature seems to be essential for a rise in ventilation, further experiments need to be carried out to determine whether in subjects working in the heat, wearing mask and hood after the attainment of a rectal temperature of 39 C or more results in hyperventilation. The subjects in this series reported severe thermal discomfort prior to the attainment of any hyperventilation with only one exception.