Contents lists available at ScienceDirect Applied Ergonomics journal homepage: www.elsevier.com/locate/apergo Ergonomic evaluation of pilot oxygen mask designs Wonsup Lee a , Xiaopeng Yang b , Daehan Jung c , Seikwon Park d , Heeeun Kim e , Heecheon You b,* a Industrial Design Engineering, Delft University of Technology, Delft 2628CE, The Netherlands b Department of Industrial and Management Engineering, Pohang University of Science and Technology, 77 Cheonam-ro, Nam-gu, Pohang, Gyeongbuk, 790-784, Republic of Korea c Department of Mechanical Engineering, Korea Air Force Academy, PO Box 335-2, 635 Danjae-ro, Sangdang-gu, Cheongju, Choongbuk, 360-060, Republic of Korea d Department of Systems Engineering, Korea Air Force Academy, PO Box 335-2, 635 Danjae-ro, Sangdang-gu, Cheongju, Choongbuk, 360-060, Republic of Korea e Department of Clothing & Textiles, Kyungpook National University, 80 Daehak-ro, Buk-gu, 702-701, Republic of Korea ARTICLE INFO Keywords: Pilot oxygen mask Ergonomic evaluation Subjective discomfort Facial contact pressure Mask slip distance ABSTRACT A revised pilot oxygen mask design was developed for better fit to the Korean Air Force pilots’ faces. The present study compared an existing pilot oxygen mask and a prototype of the revised mask design with 88 Korean Air Force pilots in terms of subjective discomfort, facial contact pressure, and slip distance on the face in high gravity. The average discomfort levels, facial contact pressures, and slip distance of the revised mask were reduced by 33%–56%, 11%–33%, and 24%, respectively, compared to those of the existing oxygen mask. The mask evaluation method employed in the study can be applied to ergonomic evaluation of full- or half-face mask designs. 1. Introduction An oxygen mask worn over the face of a fighter pilot needs a proper fit to the face for safe and effective mission accomplishment. The pilot oxygen mask supplies oxygen to the pilot when a mission is conducted at a high altitude where oxygen is lacking and houses a microphone for communication (Alexander et al., 1979; Lee et al., 2013a). An in- appropriate oxygen mask design can cause excessive pressure and/or oxygen leakage around the nasal root due to a lack of fit of the mask to the face (Lee et al., 2013a, 2013b). A pilot can be endangered during operation if moisturized exhalation air leaks through the nasal root and fogs up the visor. A pilot oxygen mask designed for better fit to the Korean Air Force (KAF) pilots’ face required an ergonomic evaluation. MBU-20/P pilot oxygen masks (Gentex Corporation, Simpson: PA, USA; Fig. 1a), worn by KAF pilots of F-15 or F-16 fighter, were initially designed using the face anthropometric data of 2420 US Air Force personnel (Churchill et al., 1977) and then improved by applying the three-dimensional face scan data of 30 male and 30 female pilots (Gross et al., 1997). A survey conducted by KAF on the usability of the MBU-20/P mask identified that a significant percentage of KAF pilots suffered from excessive contact pressure and/or oxygen leakage around the nasal root due to a lack of fit of mask to the face (Lee et al., 2013a, 2013b). Lee et al. (2013b) revised the design of the existing oxygen mask as shown in Fig. 1.b by applying 3D face anthropometric data of 336 KAF pilots collected by Lee et al. (2013a). Evaluations of performance, fit, and comfort of respirator designs for better safety and usability have been conducted. The performance of a respirator was evaluated in terms of leakage and discomfort (Arnoldsson et al., 2016; Burgess et al., 1970; Lam et al., 2016; Niezgoda et al., 2013), cognitive and psychomotor effects such as steadiness of work performance and accuracy of precision movement (Abeysekera and Shahnavaz, 1987; AlGhamri et al., 2013; Meyer et al., 1997; Zimmerman et al., 1991), physiological effects such as heart rate, respiratory rate, tidal volume, and blood oxygen saturation (Johnson, 2016; Roberge et al., 2010; West, 2013), and CO 2 rebreathing (Smith et al., 2013). Various mask fit testing methods have been proposed to assess air leakage into a respirator such as a qualitative method using aerosols (e.g., isoamyl acetate and sodium saccharin) and a quantitative method using equipment for detection of air density and flow (Coffey et al., 2002; Han and Lee, 2005; Han et al., 1997; Kolear et al., 1982; Majchrzycka et al., 2016; Rengasamy et al., 2014). Lastly, a contact pressure measurement method or a 3D virtual fit analysis between a respirator and a 3D scanned head based on finite element modeling has been utilized to evaluate the fit and pressure characteristics of a re- spirator design (Butler, 2009; Cai et al., 2016; Dai et al., 2011; Lei et al., 2012, 2014, 2013; Schreinemakers et al., 2014). The present study compared the existing MBU-20/P pilot oxygen http://dx.doi.org/10.1016/j.apergo.2017.10.003 Received 30 April 2016; Received in revised form 24 June 2017; Accepted 3 October 2017 * Corresponding author. E-mail addresses: w.lee@tudelft.nl (W. Lee), yxp233@postech.ac.kr (X. Yang), daehanj@afa.ac.kr (D. Jung), ergoparks@gmail.com (S. Park), hekim@knu.ac.kr (H. Kim), hcyou@postech.ac.kr (H. You). Applied Ergonomics 67 (2018) 133–141 0003-6870/ © 2017 Elsevier Ltd. All rights reserved. MARK