Assessment of Mask Efficiency for Preventing Transmission of Airborne Illness Through Aerosols and Water Vapor

Studies in-vitro were carefully designed to evaluate
protective attributes based on the efficiency and permeability between simple
cloth masks commonly worn in the community and those applied in hospital
settings. We evaluated efficiency
with the addition of filters that have been used in combination with cloth masks .

Initially, we evaluated efficiency on prevention of inhaled
‘fine’ particles (0.03-0.05 µm) by assessing mask
permeability of water vapor generated by a humidifier (See Water Vapor). These water vapor
particles, also capable of transmitting airborne viruses, are generated in the
exhaled breath of infected individuals while talking and present a significant
risk for infection. We then applied the nebulizer to a
spontaneously breathing 3D printed airway affixed to an adult lung model and
quantified particle deposition to the masks and filters (when applicable) and
at the level of the face, airway model, and lung model filter (see Course Particle Deposition). For this study,
we considered nebulized aerosols as “coarse” particles within the range of
particle sizes known to generate infectious airborne droplets generated through
coughing or when performing aerosol generating procedures (AGPs) by caregivers
in clinical settings.