Quantitative Fit and Breathability Testing to Evaluate and Improve Homemade Mask Design Configurations
Homemade masks are commonly used as an alternative to commercial masks to protect the general public from the spread of infectious respiratory diseases such as COVID-19. However, very little is understood concerning the influence of mask designs and the fit of masks on different face shapes and sizes. In this study, standardized quantitative fit testing was conducted with 5 participants to evaluate 48 mask design configurations. The fit of common homemade mask designs was investigated, as well as the influence of variations of nose bridges, elastic or tie options, and 23 material combinations. Relative to a surgical mask alone, double masking with a two-layer quilt cotton mask on top of a surgical mask resulted in only a 0.6% improvement in the average overall fit factor (OFF), while embedding surgical mask material layers in a homemade mask resulted in an OFF that was 58% higher than that of the original mask and was the third highest of all of the masks tested. An outer brace worn over a mask was shown to improve the average OFF of all participants by 24%. Fourteen homemade mask design configurations ranked higher than a surgical mask in regards to their average OFF, removing between 65.5 and 81.3% of particles from ambient air, 11 of which ranked higher than a KN95 mask. The pressure drop of different material combinations was also measured over a range of face velocities to evaluate their breathability. These results suggest that there are many homemade mask options that can provide just as much protection as commercially available options.