3M 7500 Exhalation Filter (Improved)

thingiverse

Finding N95s pretty uncomfortable, I bought a 3M 7500 for COVID protection in environments where the muffling of my voice wouldn't be that big a deal. But the 3M 7500 does not have an exhalation filter. Searching here, I found this design's ancestor by limhueysing, but thought I might be able to do better. I took that design as inspiration, but flipped it over so that the mount doesn't need to be removed from the mask in order to access the filter, added a flange around the mount "window" to accommodate slight variations in filter material cut without allowing air leakage (in theory), and added a cross bar on the top edge of the filter "window" to prevent air leakage/bypass on that edge of the filter material. Neither my design nor it's parent's are suitable for medical environments (there will still be a tiny amount of air leakage around the filter mount, as there is nothing to seal it to the respirator interior) but *should* be pretty good I think. Note: This should work with whatever filter material chosen. With N95 material it *will* make exhalation harder/slower, as it's a pretty small aperture (this is a byproduct of the respirator's geometry)