Breathing Air Quality Under the Fire Proximity Suit Hood.

Four subjects, wearing the fire fighters proximity suit except for gloves were exposed to low and moderate exercise regimens on a treadmill. These exercise levels plus a resting condition were combined with auxiliary air ventilation flow rates of 5 or 10 litersminute and nonventilated conditions. A continuous sample of the breathing atmosphere under the hood was evaluated for CO2 and O2 content throughout the ten minute exposure periods. The increases in heart rate are solely related to the level of exercise and were not influenced by the presence or magnitude of auxiliary air ventilation. Under the most severe conditions of this study, O2 and CO2 values did not attain levels of clinical significance. Increased activity in operational situations is a distinct possibility and CO2 levels could be elevated an additional 2-3 generating undesirable symptoms. The added weight and cost penalties of an auxiliary air ventilation system must be balanced against the possible development of an undesirable breathing environment of questionable operational significance.