I would really appreciate some advice. I have a 2yr 8month old and a 5 1/2 month old son. We just moved back after spending 2 years in the US to Bel-Air in Pokfulam for about 3 months. Both my sons have has extended colds and now although they both don't appear to you ill, still have runny nose (my older son) and constant coughing at night (the baby). My 2yr old has a runny nose all day long. My baby wakes up and you can hear so much phlegm in his throat when he coughs in the morning. My husband, who also spends most of his time at home, has post nasal drip. I am wondering if it is the air conditioner. I have an IQ air and another air filter running around the clock. And after moving back in, we had our air conditioners professionally cleaned. I personally don't have any problems but I do wake up occasionally with some phlegm. And to note, there has been some water works construction going on outside and we live on a low floor level. Have you had any similar conditions? Any doctors you would recommend that I visit? I am very stressed out about this!!