MSM is always quoting some Mask engineer online. He’s on twitter too I can’t remember his name. He does tests on masks. Looks to me as though he’s got anhome air purifier and works from his closet at home. Not exactly lab conditions. I thought his test looked so preposterous that I couldn’t even watch his boring presentations. They just looked like an add for MSM stupidity. But this is supposed to be his expertise? I don’t know.