Unfortunately they are not doing themselves any favors walking around with masks on. I get that they are worried but unless you're currently in China they are not needed.
They may not be infected but the masks are the new plague doctor outfits. It gives some people the creeps.
I actually asked someone last night at my work about why they wear one and the short answer is that they were worried about catching the disease. I then promptly explained that a surgical mask does virtually nothing to protect them from the disease.
I get that they are worried but walking around with a surgical mask won't solve anything.
I will say though, I wonder if population density in Asia is making for a fertile breeding ground in terms of outbreaks. It seems as though the most recent outbreaks have come from China. You never hear of major outbreaks starting in Saskatoon for example.
I think population density has a lot to do with it but so do things like public health and food safety policies. The Chinese version of communism evolved years ago to allow entrepreneurialism - something Stalinist communism would never countenance - so you get non-corporate residents trying to eke out a living buying/growing/raising/selling products domestically with virtually no state involvement.
Interestingly, it seems that there have not been epidemic outbreaks from the Indian sub-continent and other places with seemingly similar conditions (high density, weak public infrastructure, etc.), at least none that I can recall.