Mask pore size being larger than the size of the virus does not mean that masks are ineffective.
Masks are filtering out droplets than contain the virus. These droplets are much larger than the virus particles.
Masks are filtering out droplets than contain the virus. These droplets are much larger than the virus particles.
https://www.nap.edu/read/11637/chapter/4#23Media used for the filtration of airborne particles do not work by the same principles as those used for the filtration of liquids. Filters used in respirators and medical masks must allow the user to breathe and thus cannot clog when particles adhere to their fibers. Respirator and medical mask filters are typically composed of mats of nonwoven fibrous materials, such as wool felt, fiberglass paper, or polypropylene (see Box 2-1). The material creates a tortuous path, and various mechanisms result in the adhesion of particles to the fibers without necessarily blocking the open spaces, still allowing air to flow easily across the filter (Revoir and Bien, 1997).
This chapter will discuss three mechanisms of removing particles from the airstream: inertial impaction, diffusion, and electrostatic attraction...
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