Effectiveness of different types of mask in aerosol dispersion in SARS-CoV-2 infection. (Special Issue: Coronavirus (COVID-19) collection.)

Objective: To compare the effectiveness of different mask types in limiting the dispersal of coughed air. Method: The Schlieren method with a single curved mirror was used in this study. Coughed air has a slightly higher temperature than ambient air, which generates a refractive index gradient. A curved mirror with a radius of curvature of 10 m and a diameter of 60 cm was used. The spread of the cough wavefront was investigated among five subjects wearing: (1) no mask;(2) a single surgical mask;(3) a double surgical mask;(4) a cloth mask;(5) a valveless N95 mask;and (6) a valved N95 mask.