I took the picture that I used to create this visualization, ~ ~ ~ But even in this low-power configuration, it is easily capable of showing and measuring the gaps through the high-quality, genuine -3M-brand N95 mask that I put under it.
Yes, I saved your photo a long time ago and have shown it to others! Maybe a point worth making also is that you point out the
largest size of a coronavirus as 0.2 microns. That is equivalent to 200 nanometers. The center wavelength of visible light is about 550 namometers, the yellow-green we are most sensitive to. As such, if a medium were denser than 500 nanometers, light itself would be largely obstructed and held up, would be opaque to light! Has anyone taken their mask and put a flashlight against it in a darkened room to see if it stops light? No? Even if it did, it could still be WAY larger an openings than a virus!
In your left photo, the hash marks on the graticule as well as your circle represents about 10 microns, or 10,000 nanometers. It might actually be closer to 12 microns or 1/10th the numbered scale. Careful measurement shows that your circle would hold about 48 red dots across its diameter. Measurement of the N95 fibers show gaps in the material up to 8X larger and maybe bigger than your red circle, so let's say: gaps up to 96,000 nanometers or about 100 microns in round numbers.
That makes the LARGEST area of a coronavirus about 0.03 microns.
The area of the largest fiber gaps I see is around 4,600 microns.
So the largest gaps have openings around 150,000 times larger than the largest coronavirus and about 600,000 larger than the smallest! So up to 600,000 virus could pass through the opening at a time in a layer only 0.05 to 0.2 microns deep!
Now think of the volume of air in just ONE breath. It only takes a few thousand flu viruses to infect you. Literally millions or billions could pass through the mask in one breath.
Unless EVERY virus being inhaled or exhaled is trapped within a water droplet to be captured by a fiber AND those droplets don't evaporate in continued use releasing most of them again into dry air, the masks are a total joke for protecting against viruses and you'd have much better luck trying to catch rain using your tennis racket.