Infection by a virus like coronavirus is often through the nasal passages or the eye. At time it may be inhaled via the mouth or transferred via food.
However, if one looks at the masked Chinese one see glove-less hands and cell phones. The cell phone is the petri dish for corona. The device is swung about, exposed to everything, holds virons, transfers them to hands and from there to eyes. The mask at best prevents expelling outwards. The eyes are unprotected but they are great sites for internal infection.
When in a potentially infectious site, I would focus first on eyes, then hands, then nose, then mouth, then whatever else can be covered. But when looking at pictures from China the eyes and hands are all exposed and most are carrying cell phones. They become walking transmitters of the virus.