key: cord-0966305-2sqtqf65
authors: Scott, A.R.; Hu, J.; Gan, C.; Morris, J.A.; Meacham, K.W.; Ballard, D.H.
title: Safety concerns for facial topography customized 3D-printed N95 filtering face-piece respirator produced for the COVID-19 pandemic: initial step is respiratory fit testing
date: 2020-09-14
journal: Int J Oral Maxillofac Surg
DOI: 10.1016/j.ijom.2020.08.017
sha: ca374e016a5c1cf2abc3b7818047663fe4c22507
doc_id: 966305
cord_uid: 2sqtqf65

nan

their determination in providing rapid solutions to personal protective equipment (PPE) shortages during times of crisis. However, we feel that it is misleading to provide a face mask solution without discussion of proper fit testing (quantitative or qualitative), which importantly may put individuals trying to replicate it at increased risk.

The authors aptly note in their discussion that filter efficiency and individual fit are essential components of mask performance in practical usage, however poor fit is responsible for greater particle penetration than poor filtration for commercially available solutions 2 . The authors subsequently provide an image of a sterilization nurse wearing the 3D mask prototype as evidence, stating "Note the good clinical fit of the 3D-printed face mask". Such statements are potentially misleading to the reader; poor fit may be imperceptible to both users and observers without quantitative metrics, and to rely on subjective measures of fit creates undue danger for the mask user 3 . The authors moreover imply that further testing of their solution is only "ideally required" rather than a necessary component of a mask solution implementation. Even commercially available masks are affected by poor fit; a single institution study in Japan noted that 30% of commercial N95 users experienced poor fit, which was reduced to only 4.5% with proper testing and user instruction 4 Administration-certified 7-minute quantitative fit testing; however, this directed letter is not the medium to fully present or discuss those data. Regulatory agencies such as the US Food and Drug Administration acknowledge the efforts of attempts at 3Dprinted PPE 5 , but state doubt regarding their effectiveness; "For example, 3D-printed PPE may provide a physical barrier, but 3D-printed PPE are unlikely to provide the same fluid barrier and air filtration protection as FDA-cleared surgical masks and N95 respirators" 6 .

We would welcome the authors' clarifications on these points of additional testing, particularly if the 3D-printed N95 alternative successfully passed fit testing, and hope that their continued work will help provide effective real-time PPE solutions in times of further crisis.

Custom-made 3D-printed face masks in case of pandemic crisis situations with a lack of commercially available FFP2/3 masks

Performance of an N95 filtering facepiece particulate respirator and a surgical mask during human breathing: two pathways for particle penetration

Health care workers and respiratory protection: is the user seal check a surrogate for respirator fit-testing?

Evaluation of quantitative fit-testing of N95 filtering facepiece respirators using Mask-Fitting Tester and improvement of mask fitting by instruction

COVID-19 Supply Chain Response Collection. NIH 3D Print Exchange

FAQs on 3D printing of medical devices, accessories, components, and parts during the COVID-19 pandemic. Food and Drug Administration Website

None.