Actually it's more of a fashion trend in Japan. South Koreans just kinda copy what the Japanese are doing (which is pretty much true of all Korean pop-culture :P lol)
And I'm not even sure I fully understand why I like surgical masks, either. I just know that I've been attracted to people wearing them since I was 3, long before I knew about fetishes or even sex in general! XD
Actually it's more of a fashion trend in Japan. South Koreans just kinda copy what the Japanese are