My bro pointed out the outcome of air pollution in HK. IMO, it seems to depend on the direction of the wind and if it's blowing from the Mainland, then the smog seems to be worst.
I am pretty sure it has gotten a lot worse since, I was back in 2007 (and 2008, me thinks), definitely a lot more smog. Was there for summer and month of Jan/Feb. (I know I have some pics somewhere.)
My cous got married early this year and she had her pics taken at the harbour and HK was pretty smoggy, a pity though.
Thanks, bro, for pointing it out.