I bought an air-purifier for my daughters room so that at least at night and for sleeps I know she is breathing clean air. My daughter is 3, has lived her whole life in HK and never had respiratory problems - other friends have not been so lucky. I think you should also look at where you live - if you are concerned about the polution where you are there are some nice "country" areas of HK where the air quality is much better than on the island. This could mean a longer commute for the workers in the family - but worth considering if things like asthma run in the family. Baby #2 is on the way - I know for us the decision to have kids here was more economic than anything else. There is no way we could have had a family living in Australia - childcare would have crippled us, and as much as I love my daughter I'm not ready to give up work.