We have a portable HEPA filter unit in our living area to help with my wife's COPD. We have a open plan so the kitchen and dining area are connected. It seems to work quite well. It has 3 speeds indicated by blue, orange, or red indicator lights. It runs continually on low(blue) and is almost silent. Sometimes when we are cooking, esp if we are frying, it will kick into orange or even red for a little while before reverting back to blue. I suspect that it does that faster than our furnace filter would clean the air in the whole house, which is about 3 times the volume.