Tracy, I've been testing different materials which can substitute coffee filter while offering better protection as a DIY face mask/respirator. I have reasons to believe 'Qualitative Filter' based face mask does that.
You can read the Research, Design, Caveats on my website (DIY Qualitative Filter Face Mask) - https://abishekmuthian.com/diy-qualitative-filter-face-mask/.
Stay Safe.