Very small rocks in the air

I've discovered something truly monumental about Japan and Hong Kong: their air is filthy, by which I actually mean really, really, really dusty.

Before I say much else, let's also consider this:

a. Japan and Hong Kong are both small countries, about the size of California and nearly the size of New York City, respectively. So, there can't be much pollution going on, right?

b. Japan is an island. Hong Kong is a coastal city... er..., I mean country... uh, state... region, whatever. So, should mean lots of clean ocean air to sweep away all the dirty stuff, right?

c. I'm guessing, from having lived in Japan and now living in Hong Kong, that it rains a good deal in both places. More so in Hong Kong, I'm sure. It should seem intuitively obvious to people like me (without advanced degrees in meteorology and whatnot) that so much rain should keep the dust in the air at bay.

Regardless of what I think I know about weather patterns and geography, I do know one thing: that I can spend all day thoroughly cleaning my apartment, leave my window open for one afternoon, and after a few hours have a fine layer of dust covering anything and everything with a flat surface. I've experienced this in Japan and am experiencing it now here in Hong Kong. And I can understand this happening if I lived in the city centre of Hong Kong, but I live in New Territories. It's the countryside. The jungle. The boonies. Behind my building is a mountain with enough foliage to be a small rain forest. I expect toucans and parrots (which I've seen) to leave toucan and parrot turds on my balcony (no such luck; only dead lizards baked dry by the sun). Just a few train stops away from my station, people continually have trouble with monkeys getting into their rubbish bins. Not cats, mind you. Monkeys.

However, it makes sense too. I've postulated a bit, and have come up with my own reasons why the air in Japan and Hong Kong are so dusty. For Japan, it has nothing to do with pollution or overpopulation (especially now, since Japan is experiencing it's first decreasing population in over 100 years); the dust comes from a single source: lint from futons being hung out on patios and balconies to air out. You see this everywhere you go in Japan: futon blankets and mattresses slung over patio and balcony railings, and indeed, anywhere they can be hung up. Cripes, you can even buy special laundry clips (they look more like vise clamps or those special forceps with which doctors use to yank stubborn babies out of the womb). It's an epidemic.

In terms of Hong Kong... well, it should have been obvious to me from the start. One word: C-H-I-N-A.