first of all, i've never heard of anyone recommending dongguan before as a good place to live.

second of all, shenzhen is also renowned for bad air quality.

third of all, i read that the pollution in HK has gotten much worse over the past few years because they're getting the pollution from the factories in Dongguan. And many HK residents have moved to Singapore as a result of the increasing pollution.

So I find it hard to believe that the air in some parts of Dongguan is not that bad given that it has the highest concentration of factories in china (probably) and it's so bad that it's affecting HK air.

But you live there, so you would know better than me I guess.

Giardia isn't unique to Yunnan. It's common where I'm from in California.

geogramatt... yep beaver fever can be found in usa too. but probably harder to get unless you go camping, in yunnan you don't need to go camping in the woods.