Minimizing Aerosol Leakage from Facemasks in the COVID-19 Pandemic.

Background: Aerosol therapies with vented facemasks are considered a risk for nosocomial transmission of viruses such as severe acute respiratory syndrome coronavirus 2. The transmission risk can be decreased by minimizing aerosol leakage and filtering the exhaled air. Objective: In this study, we determined which closed facemask designs show the least leakage. Methods: Smoke leakage was quantified during in- and exhalation in a closed system with expiration filter for three infant, six child, and six adult facemasks (three times each mask), using age-appropriate anatomical face models and breathing patterns. To assess leakage, smoke release was recorded and cumulative average pixel intensity (cAPI) was calculated. Results: In the adult group, aircushion edges resulted in less leakage than soft edges (cAPI: 407 ± 250 vs. 774 ± 152) ( p  = 0.004). The Intersurgical ^® Economy 5 mask (cAPI: 146 ± 87) also released less smoke than the Intersurgical ^® Clearlite 5 (cAPI: 748 ± 68) mask with the same size, but different geometry and edge type ( p -value <0.05). Moreover, mask size had an effect, as there was a difference between Intersurgical ^® Economy 4 (cAPI: 708 ± 346) and 5, which have the same geometry but a different size ( p -value <0.05). Finally, repositioning masks increased the standard deviations. Mask leakage was not dependent on breathing patterns within the child group. Conclusions: Mask leakage can be minimized by using a closed system with a well-fitting mask that is appropriately positioned. To decrease leakage, and therewith minimize potential viral transmission, selecting a well-fitting mask with an aircushion edge is to be recommended.