  Layered systems of commonly available fabric materials can be used by the
public and healthcare providers in face masks to reduce the risk of inhaling
viruses with protection about equivalent or better than the filtration and
adsorption offered by 5-layer N95 respirators. Over 70 different common fabric
combinations and masks were evaluated under steady state, forced convection air
flux with pulsed aerosols that simulate forceful respiration. The aerosols
contain fluorescent virus-like nanoparticles to track transmission through
materials that greatly assist the accuracy of detection, thus avoiding
artifacts including pore flooding and the loss of aerosol due to evaporation
and droplet break-up. Effective materials comprise both absorbent, hydrophilic
layers and barrier, hydrophobic layers. Although the hydrophobic layers can
adhere virus-like nanoparticles, they may also repel droplets from adjacent
absorbent layers and prevent wicking transport across the fabric system.
Effective designs are noted with absorbent layers comprising terry cloth towel,
quilting cotton and flannel. Effective designs are noted with barrier layers
comprising non-woven polypropylene, polyester and polyaramid.
