I'm at a layover at the Helsinki airport, and there a bunch of Chinese chicks, and they all have face masks on. I have noticed this in St. Pete a lot as well. The men don't seem to wear them, although maybe I only check out the chicks.
(Of course, I could be wrong about the ethnicity as East Asians look almost the same, but I think I can tell the difference between the Han Chinese, Japanese & Korean.)