In Japan, people wear surgical type masks when they have a cold or the flu. People also wear them during allergy season, and as means of protection from said illnesses. It makes sense as we are a very crowded society smashed together on subways. I too, was raised with this culture so I don't notice it when I go home and see people--until I have a foreigner with me. Everyone I brought home have gasped and/or commented on the look. I can see how it would appear creepy to have crowds of people wearing masks.
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We. Are. Mask. Wearing. Robots.
(www.news.janjan.jp)
And what's amazing is that now there are all sorts of different masks for different needs:
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Masks for men
(www.livingincairns.com.au)
Masks for women
(www.saihatei.com)
Masks for kids
(blog.qlep.com)
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Special allergy blocking masks
(item.rakuten.co.jp)
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Masks with a slight curve so it sits better on your face, and...
(www.excite.co.jp)
Masks that have a small metal piece to shape it around your nose so that if you wear glasses, they won't fog up.
(item.rakuten.co.jp)
I suppose it's natural that if you use something often and a lot, people would put effort into improving it and making money from it. I have no idea if this is effective. I don't know if wearing masks has prevented others from getting sick. The amount of people wearing them during flu season is so much, it seems a bit pointless then. Are we trying not to mix up illnesses? Who knows? At least it appears as thoughtful. It's the equivalent of sneezing into your elbow, which I bet doesn't happen in Japan.
I don't see this trend taking off in the States anytime soon.