Research has shown that masks offer inward protection by filtering out droplets:
Filtering effect for small droplets (aerosols) by various masks; home-made of tea cloth, surgical mask (3M “Tie-on”) and a FFP2 (N95) respirator mask. The numbers are scaled to the reference of 100 (source of droplets) for illustrative purposes, calculated from the PF (protection factor).”
Cambridge scientists tested 0.02 micron Bacteriophage MS2 particles (5 times smaller than the coronavirus) & compared homemade masks made of different materials to surgical masks.
Surgical mask blocks 89%
Vacuum cleaning bag 85%
Dish Towel 73%
T shirt 70%#macgyvercare pic.twitter.com/RFEbhH1V5D
— C. Michael Gibson MD (@CMichaelGibson) March 17, 2020
“CDC recommends wearing cloth face coverings in public settings where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies), especially in areas of significant community-based transmission.
CDC also advises the use of simple cloth face coverings to slow the spread of the virus and help people who may have the virus and do not know it from transmitting it to others. Cloth face coverings fashioned from household items or made at home from common materials at low cost can be used as an additional, voluntary public health measure.”
“What the [Wake Forest Baptist Health’s] test team found was that the masks’ effectiveness varied widely. The best homemade masks achieved 79% filtration as compared to surgical masks (62% to 65%) and N95 masks (97%). But other homemade masks tested performed significantly worse, sometimes demonstrating as little as 1% filtration, Segal said.
The best-performing design was constructed of two layers of high-quality, heavyweight “quilter’s cotton” with a thread count of 180 or more, and those with especially tight weave and thicker thread such as batiks.”