Commented on Filter Test Kits for 3D-printed Reusable Masks 22 days ago
Turns out that to meet requirements for protection against aerosol transmissions, the BEmask design needs 2 layers of MERV 15 filter material which makes breathing too difficult to be practical, and the seal to the face must be perfect also. My opinion (from our testing) is that the filter needs to be at least 8 square inches, double the original BEmask (or the Montana Mask) size. Testing for the efficacy against aerosol COVID-19 virus requires vigorous testing protocols that are not available to do-it-yourself designers. However, I am moving forward with 8 square inches (52 square centimeters) as a rule of thumb. Larger than that will be better than that for breathability at N95 standards.
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