Funny you mention the pneumonia thing. I spent a couple of years in my mid-twenties in construction, working outside in the winters, and got pneumonia once. That was 15 years ago. I've had bronchitis three or four times since then, as well, though the last bout was almost a decade ago. And last year I rode my bike right into October, but found I would get sore in my one lung, the one that had had the pneumonia, whenever temperatures dropped under 15 degrees. Which is kind of a problem when you cycle and you live in Canada.
Then I quit smoking.
Ha! I've ridden all fall this year, and indeed right up to now, the end of December, in single digit temps and even below zero, with no discomfort at all. I used to pooh-pooh my wife's constant whining about the smoking, saying that I didn't smoke that much so it wasn't a big deal, but it actually was, and over the past year my lungs have reaped the benefits.
Living in Taiwan is like smoking two packs of cigarettes per day. Add on the humidity, the lack of hygiene and the crowded conditions, and a simple cold that would call for chicken soup and maybe a day in front of the television on this side of the Pacific can turn into a month of suffering in Asia, if not worse. I certainly understand the desire to use some kind of mask when in Taiwan. I think I'm fortunate to be living in a smaller city in southern Ontario where it takes just five minutes to get to the countryside. Aside from pig and chicken manure, and the odd time that I get caught downwind from a chemical sprayer in a field (which is probably kinda nasty, but I don't want to know about it), the air here is pristine.
P.S. Were you going to post a photo in your previous post?