The home-grown masks I've been seeing suggest HEPA filters are suffocating, and the sweet spot [protection/breathability] is a layer of cotton-polyester T-shirt material and a layer of 'anti-microbial' cloth. I don't know if that would be high-denier or having silver threads.
edit:
Jack Rikard gave his Corona virus take — CoronaVirus Stuff - Stock Picks Going Forward - EVTV; at
https://youtu.be/-IGtmgYkq0w?t=3696 he suggests approaching-N95 levels with a disposable baby diaper worn
pantsu -style plus a pair of goggles.
It could be the new thing. I also hear that Everclear is a good hand sanitizer .