Why is this girl sitting across from me wearing a surgical face mask?

I'm in a library. She is sitting there doing homework in this mask. Every 5 minutes she takes the mask off, inspects it, and puts it back on. This has been happening for about an hour.Why is this girl sitting across from me wearing a surgical face mask?
She may have a sensitive immune system that requires her to wear one, or she may just have a bad cold or illness that she doesn't want to spread.Why is this girl sitting across from me wearing a surgical face mask?
She is afraid of germs or has a weak immune system
why do you want to know?
Some people wear them because they are intolerant of fragrances. She's probably inspecting it because you're staring at it and she thinks you're staring because there's something wrong with it. Of course, she may not realize that it makes her look like a nut.
She may be on chemotherapy and needs to protect herself from germs since getting sick can cause problems. Or maybe she has severe allergies.
She's a vampire.
perhaps she has an infectious disease and she doesn't want to contaminate the air...or





maybe shes just a germaphobe.