I'm pretty aware of how large a TB bacillus is, thanks. The NIOSH definition for an N95 is a device able to filter at least 95% of airborne particles that have

I'm pretty aware of how large a TB bacillus is, thanks. The NIOSH definition for an N95 is a device able to filter at least 95% of airborne particles that have a mass median aerodynamic diameter of 0.3 micrometers. While SARS-CoV-2 is around 0.1 microns in size, naked COVID-19 viruses in air are rare as they would be torn up nearly immediately, so they are almost always within aerosols. Typical respiratory aerosol range is around half a micron or so [0], and as the aerosol particle size gets smaller, so necessarily must be the amount of virus that is present. Is this perfect filtration? No, but no one gets sick from a single virus they inhaled either, even with as communicable as the current Omicron variants are. There's a minimum infective dose and they help keep exposure under it. [0] https://www.nature.com/articles/s43856-022-00103-w https://www.nature.com/articles/s43856-022-00103-w