“One of the common criticisms of face coverings centers around particle size. People will say that wearing a cloth mask to stop a virus is like “using a chain link fence to stop a mosquito.” It’s not!
Here’s why: first of all, a mosquito has its own mean of locomotion. It can fly directionally and intentionally to avoid any portion of the fence that would impede its motion, whereas SAR-CoV-2 is completely dependent on being projected by its host (the human) and being transported via fomite transmission (surface contamination and touch transference to another host) or via air currents.
Secondly, the large gaps in the fence and tiny mosquito portion of the analogy fails as well.
While it’s true that the weaves of face covering vary in size and coronaviruses are extremely small (0.1-0.5 µm), the purpose of a face covering is mainly to reduce respiratory droplet spread and droplets are significantly larger than the virus itself at 5-10 µm.”
https://www.cihc.info/covid-101-is-a-mask-like-a-chain-link-fence/