This was posted on the US national library of medicine, national institute of health:

link to article

 

copied from the text:

 

Efficacy of facemasks

The physical properties of medical and non-medical facemasks suggest that facemasks are ineffective to block viral particles due to their difference in scales ^{[16], [17], [25]}. According to the current knowledge, the virus SARS-CoV-2 has a diameter of 60 nm to 140 nm [nanometers (billionth of a meter)] ^[16], [17], while medical and non-medical facemasks’ thread diameter ranges from 55 µm to 440 µm [micrometers (one millionth of a meter), which is more than 1000 times larger ^[25]. Due to the difference in sizes between SARS-CoV-2 diameter and facemasks thread diameter (the virus is 1000 times smaller), SARS-CoV-2 can easily pass through any facemask ^[25].

 

Maybe re-think the face-daiper strategy? fire away crowd ????

Fact check:

https://www.poynter.org/fact-checking/2021/do-masks-really-work-here-are-politifacts-answers-for-mask-skeptics/

 

Please note:

The diameter of the virus per se is one thing, the diameter of the aerosols to which the the virus is bound when a person infected with SARS-Cov-2 exhales, coughs or sneezes is another.