electrostatic air filter on your aircon evaporator air intake
Let me know where you buy such things (or anything that actually works) and I am the first one to put my credit card down.
Had an air filter for some other purpose (working on PCBs/electronics) but not sure if it worked.
Most of us don't even clean our air conditions often enough. And to be honest, I am not sure if these aircon service companies in HK actually do the real cleaning or just remove visible dirt.
Found the following info on the Hedley page:
A special high-tech air filter can improve indoor air quality considerably, but obviously you will only benefit from reduced exposure for as long as you stay in the same room. Additionally, effective air filters are very expensive and require frequent replacement. Ordinary air-conditioning and dehumidifier filters will not help as they can only remove the largest dust particles, and not the ultra-fine particles or gases that are most damaging to your health.