Gates Open Research | 2021
Assessment of mask efficiency for preventing transmission of airborne illness through aerosols and water vapor
Abstract
Background: Currently the Center for Disease Control has advised the use of face coverings to prevent transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to those who are unvaccinated. This study seeks to evaluate if cloth masks have increased efficiency with the addition of a filter material. Methods: An adult airway and test lung model were exposed to nebulized ‘coarse’ aerosol droplets (0.5-11 µm) and humidified ‘fine’ water vapor particles (0.03-0.05 µm). Aerosol was quantified based on particles deposited on the face, airway and lung model. Tracheal humidity levels characterized fine particle permeability. Both phases of testing were conducted by evaluating the following testing conditions: 1) no mask; 2) cloth mask; 3) cloth mask with Swiffer™ filter; 4) cloth mask with Minimum Efficiency Reporting Value (MERV) 15 filter; 4) cloth mask with PM2.5 filter 5) surgical mask and 6) N95 respirator. Results: All mask conditions provided greater filtration from coarse particles when compared to no mask (P<0.05). All cloth mask with filter combinations were better at stopping fine particles in comparison to no mask. A cloth mask without a filter and surgical mask performed similarly to no mask with fine particles (P<0.05). The cloth mask with MERV 15 filter and the surgical mask performed similarly to the N95 with course particles, while the cloth mask with Swiffer™ performed similarly to the N95 with the fine particles (P<0.05). Conclusions: Respiratory viruses including SARS-CoV-2 and influenza are spread through exposure to respiratory secretions that are aerosolized by infected individuals. The findings from this study suggest that a mask can filter these potentially infectious airborne particles.