I have to say that Dubai seems to be better for kids than HK. I have heard similar stories of people having to move within HK or just flat out leave due to high levels of pollution causing health issues.
Dubai is in such flux, it's difficult to predict even 6 months ahead. They just anncounced closure of a golf club that was home to many EK golfers for example. Beach clubs are still avail and quite good but you really need to check the place out.