[exDemMom]

A cotton quilt with batting provides 96 ± 2% (10 nm to 300 nm) and 96.1 ± 0.3% (300 nm to 6 μm) filtration of these droplets.

Cotton is absorbent. That is a huge help to removing viruses that you exhale. (I think the filtration is achieved by factors in addition to the pore size between threads. A less absorbent material would not work as well.)

[Mom MD]

cotton is absorbent u til it is saturated by moisture from your breath. about 20 minutes. Not that any breathable material protects from the virus anyway