Characterizing Fit Factor of a One Size Fits-Most Emergency Mask using Subjects with Smaller Neck Circumferences

The Emergency Mask (EM) is an integral part of fire response on the International Space Station (ISS), Orion, and Gateway. The EM is a hood protection respirator sealing around the subject’s neck, with an additional nosecup covering the subject’s oral/nasal region. When integrated with a pair of air-purifying cartridges, the system can provide safe breathing air in a post-fire environment. Initially, the EM was certified as a one-size-fits-most respirator; however, a recent requirements scrub discovered that the initial requirement set did not include the neck circumferences of the smallest possible crew population. To investigate whether the requirements gap would pose a problem for the current EM design the project performed fit tests on eight subjects with neck circumferences smaller than the initial EM requirement. The test included subjects donning an EM and performing head movements in a tent filled with approximately 50,000 particles/cc of smoke particles. During these motions, particulate measurements are obtained from within the EM and compared with particulate measurements in the surrounding environment. This paper provides descriptions of the test hardware, methodology, and results, which have provided the rationale for designing and building an EM to accommodate subjects with smaller necks.