Very nice diagram.
Why wear a mask, if the virus is too small for the mask to stop it?
The usual reasoning is that the mask stops respiratory droplets, which are 10-20 times the size of the virus, and that gives us a chance to stop the virus before it can leave those droplets and make it to our mouths, noses, or eyes.
Put on a clean mask with clean hands, change your mask frequently, don’t touch the mask thereafter until you are ready to take it off, don’t touch anything else in your environment if you can help it (and don’t touch your eyes, nose, or mouth with “dirty” hands), put on a new fresh mask using clean hands every 60-90 minutes, and wash your hands frequently, and then you can decrease both the chance of getting the virus particles into your lungs (or eyes, or mouth, etc.) and the chance of transmitting virus-laden respiratory droplets from your mouth and nose to your environment (to others).
Now, how many people do you think really do all the above? How many children in school will do even a pittance of that?
Right! Basically, none.
If you are sick, especially if you are coughing, sneezing, having a runny nose or runny eyes, use a mask to help prevent transmission, but if you are not sick, why wear a mask, especially if you won’t be doing it effectively (as outlined above)?
No, masks for the healthy is just a superstitious thing, like wearing a crystal or amulet or poultice or religious symbol, and masks do nothing but provide a false sense of security for the overly anxious.
IMHO
Like using a chicken-wire helmet to protect against mosquitos and bees.