Examining the effects of custom 3D-printed respirator frames on the seal of KN95 masks: A pilot study

During most of the COVID-19 pandemic, N95 respirators were in short supply, creating a need for alternative solutions to protect healthcare workers and others from infection. The current pilot study was conducted to determine whether using a KN95 respirator with a custom respirator frame would be an effective alternative to an N95 respirator. Using the Bellus3D Dental Pro application on an iPhone, a 3D face scan was obtained for six adult volunteers (three women, three men), and a custom mask frame was 3D printed in gray resin. Next, a PortaCount Fit Tester was used to test the fit of a KN95 respirator, a KN95 respirator with the custom mask frame, and an N95 respirator. The three respirator configurations were compared for overall fit and fit during four day-to-day movements (bending over, talking, and moving the head side to side or up and down). Fit factor values could range from 1-200, and a value of 100 was considered the minimum to meet established safety specifications. The mean (SD) overall fit factor was 12.1 (1.8) for the KN95 respirator, 195.4 (11.2) for the KN95 respirator with the custom mask frame, and 170.0 (38.3) for the N95 respirator. Differences were found between the three configurations for all outcomes (all p < .004). Post hoc comparisons indicated differences between the KN95 respirator and KN95 respirator with the custom mask frame for all outcomes (all p < .02) and between the KN95 respirator with the custom mask frame and N95 respirator for moving the head side to side (p = .04). Results of the pilot current study suggested using a KN95 respirator with a custom mask frame significantly improved the fit factor to meet existing safety specifications. In the future, healthcare workers and organizations should consider this configuration as an effective alternative to N95 respirators.