An improved and highly efficient geometry for facemasks

Abstract

\n Wearing masks and face coverings helps reduce transmission of respiratory diseases. Much prior research on mask filtration efficiency has focused on fabric type, with little consideration given to mask geometry. Here, we present evidence that increasing the mouth-mask separation distance engenders an increase in the mask-fabric filtration efficiency towards expiratory aerosols emitted via vocalization, which we attribute to a decrease in the expiratory jet velocity. We further assess the performance of a new reusable cloth facemask design, originally made for professional singers and having a large mouth-mask separation distance. With proper fitting, these masks achieve overall filtering efficiencies of >93% for both exhaled expiratory aerosols from singing and speaking and for inhaled ambient aerosols, better than surgical masks and approaching N95 respirators. The mask design also provides for less inhibited mouth and jaw movement, suggesting it may provide a more palatable, high-efficiency alternative to medical-grade masks for the public.