3M Mask Exhaust Filter Adapter

thingiverse

WHO recommendation is to wear a cloth mask to reduce exhalation of droplets and the chance of spreading COVID-19. Half-mask respirators have inlet and outlet valves (see the white and pale blue discs in the inside-the-mask picture) to pass incoming air through the filter and bypass warm, moist exhalation past the filters. Thus, *exhalation is not filtered*. For COVID-19, an exhaust filter should be added to prevent transmitting any (asymptomatic) infection. The initial exhaust filter is a simple fabric tube held in place by hair bands, rubber bands, tape, etc. The exhaust pressure is very low. Outlet filter choice may depend on materials at hand and your sense of humor. Any shape (bag, circle, triangle, a thickly-woven sock) would work. I used a gray fabric tube (to match the mask) as the outlet filter, with a visual effect much like an elephant's trunk. Dimensions were obtained from the particular 3M mask I had using calipers. Perhaps there are CAD models available. This is an early version, but works quite well (stays in place with one broken latch, probably because it's pressed onto a molded silicone piece). It could probably be smaller or thinner; I was aiming for rugged and minimal flow restriction. My preferred compensation is to print an extra for someone else with the same type of mask, or adapt to another model, and help save lives. Thank you, and stay safe!.