Risk Assessment of Bacteriologic Health Hazards in the Helmet Bladder Componentof a Pressure Breathing for G (PBG) System

摘要

One of the components of the experimental development G protection ensemble knownas STING (Sustained Tolerance to INcreased C) is a breathing loop consisting of a pressurized oxygen supply, regulator, face mask, and an inflatable helmet bladder. The bladder, located in the back of the pilot's helmet, at the occipital level of the skull, inflates during the positive pressure breathing phase of the Pressure Breathing for C (PBG) cycle. The bladder is inflated to the same pressure as the mask, thus pulling the mask tighter to the face; preventing mask leakage; and, ensuring an adequate supply of pressurized oxygen to the user. Upon cessation of PBG, the helmet bladder deflates. The helmet bladder is effectively a blind sac' in an otherwise open system. This fact has prompted the Aerospace Engineering Test Establishment (AETE) to express concern over the possibility that the bladder could serve as a reservoir for microbiological contaminants (bacterial or fungal). If such contaminants were present, deflation of the bladder, upon cessation of PBG, may result in contamination of the breathed oxygen. If so, this would pose a health hazard to the individual.