The pollution in China can be time of year dependant. I have...

The pollution in China can be time of year dependant. I have been 6-7 times and I have been in Beijing and Guangzhou when the visibility is only a few hundred metres (seriously in the city I could not see a skyscraper a few blocks away) and my ex's asthma was so effected she could not go outside. I been to Hong Kong probably 10 times and most of the time the skies have been clear, but the last two times the pollution was horrific.

There is a lot of social unrest in China because of this problem and they are spending hundreds of billions of dollars trying to fix it (I was told that figure by a consultant working on a project there).