Improving the fit of filtering facepiece respirators.

Aims To assess the effectiveness and acceptability of smartphone customised frame technology to improve the fit of disposable filtering facepiece class 3 (FFP3) respirators for dental staff who previously failed fit testing.Method In total, 20 volunteers who previously failed FFP3 fit testing were recruited to use smartphone technology (Bellus3D FaceApp) to have a 3D-printed bespoke face frame produced for them. They underwent qualitative fit testing with and without the frame with two freely available disposable FFP3 respirator designs (mask A: GVS F31000 Segre folded model; mask B: Valmy Spireor). The order of testing was random. Ease of use of the smartphone technology and the comfort of the frame were determined by questionnaire.Results Fit test passes increased from 5% without the frame to 70% and 95%, respectively, for masks A and B with the frame (p <0.01). Very few participants reported using the technology as difficult (n = 1/20) or the frame uncomfortable (n = 3/20) or difficult to wear (n = 0/20).Conclusion Customised frames produced using smartphone technology improved qualitative fit test pass rates for two commonly available FFP3 respirators. Using smartphone technology for frame design, wearing a frame and frame comfort levels were all acceptable to the majority of participants.