Hitting N95 grade filtration
Study I was involved with:
- You can sew a mask that can get 96% or higher particle filtration effectiveness from incredibly cheap fabric that's abundant (spunbond polypropylene - no electrostatic charge needed)
- A regular sewing machine can do it, and there's no hemming involved.
- Don't wash it though as it'll lose filtration. Instead wear it for a few weeks before replacing it.
- If China halts exports of melt-blown polypropylene for PPE use, the world had a 30 cents each contingency mask.
- more studies needed
While people should seek N95, FFP2, FK94 and KN95 to protect themselves, some will not be able to afford those or find them for sale. Home sewn is an imperfect option. Seamstresses would need to source the spunbond polypropylene fabric and some wire. A regular sewing machine is fine. While the pattern uses a zig-zag stitch, it is possible with just a straight line stitch.