Assessing the Fit of N95 Filtering Facepiece Respirators Fitted with an Ear Loop Strap System: A Pilot Study

Abstract

Throughout the COVID-19 pandemic, hundreds of millions of people worldwide have become new users of respiratory protective devices. Facemasks and KN95 respirators utilizing an ear loop straps system (ELSS) have recently become popular among occupational and non-occupational populations. Part of this popularity is due to the ease of wearability as compared with traditional devices utilizing two headbands, one worn over the head and the other behind the neck—a universal strap system used in NIOSH-certified N95 filtering facepiece respirators (FFRs). Some users convert the two-strap configuration to an adjustable ELSS. The first objective of this pilot study was to quantitatively characterize how such a conversion impacts the respirator fit. Additionally, a novel faceseal (NFS) technology, which has been previously demonstrated to enhance the fit of N95 FFRs, was deployed to modify the ELSS-converted N95 FFRs. The second objective of this study was to quantify the fit improvement that results from adding the NFS to the ELSS. The study was conducted by performing the Occupational Safety and Health Administration (OSHA)-approved quantitative fit testing (QNFT) on 16 human subjects featuring different facial shapes and dimensions. Three models of cup-shaped N95 FFRs were tested in three versions: the standard version with manufacturer’s strap system, the ELSS-converted, and the ELSS-converted version modified by adding the NFS. QNFT demonstrated that the fit of an N95 FFR featuring the traditional/standard headbands strap system is negatively impacted when this system is converted to an ELSS. The fit of an ELSS-converted respirator can be significantly improved by the addition of the NFS. We found that the FFR model and the strap system version are significant factors affecting the QNFT-determined respirator fit factor (FF), as well as the OSHA QNFT pass rate (FF ≥100). The findings suggest that the current NFS, if further improved, has a potential for developing a ‘universally fitting’ ELSS-equipped N95 FFR that can be used by the general public, the vast majority of whom do not have access to OSHA fit requirements.

Combining PCA-AHP Combination Weighting to Prioritize Design Elements of Intelligent Wearable Masks

“…This is not difficult to comprehend, as those who have experienced COVID-19 are well aware that the pain behind the ear induced by wearing the mask for extended periods of time is a source of discomfort that the majority of people find intolerable. On the subject of reducing discomfort behind the ear, one might refer to the study by Xinyi Niu et al [49] in which the ear loop strap system (ELSS) was shown to prevent pain behind the ear. Using the Ergonomics Function Deployment (EFD) method, Prahesti, A., et al suggested four conceptual designs, with the adjustable ear loop and head loop rating the highest [50].…”

“…We believe that the reason matching face shape has a lower priority than adjustable ear straps is that this element has a weaker impact on daily life, and the users affected by it are primarily concerned with the psychological aspect of the user or wear glasses. The innovative facial seal (NFS) technology [49], which has been proven to improve the fit of masks to the face, is proposed for adoption [51]. Lightweight has the lowest priority in terms of comfort, most likely because the mask is not widely available and because this element is unique to smart wearable masks versus ordinary masks, which may have led to incorrect judgments by some testers.…”

Overview of tight fit and infection prevention benefits of respirators (filtering face pieces)

“…Indirectly, however, this study demonstrated an inadequate tight fit for an additional 12 respirators of the coffee filter shape with ear loops from different manufacturers. The disadvantage of fastening respirators by ear loops was confirmed experimentally by converting some respirators from fastening by means of head straps to length-adjustable ear loops with the respirator body remaining unchanged, and subsequently an adequate tight fit could no longer be achieved despite the ear loops being adjustable to the anatomy [ 25 ]. For this reason, some governmental occupational safety organizations indicate that respirators with ear loops do not provide adequate protection as tight fitting respiratory protective equipment [ 26 ].…”

Innovate and Stockpile: Respiratory Protection for Essential Workers in a Catastrophic Pandemic

“…In addition, KN95-style flatfold respirators with ear loops became popular, especially among the public. Replacing head straps with earloops, however, decreases fit significantly, as investigated by Niu et al 11 …”