My wife and I have lived in a new construction house for 2 years and the entire time we have noticed that there seems to be a large amount of dust in our house. I replace the furnace filter roughly every 3 months, and it is always very dirty (seems caked with dust). I began to think that since it is new construction, that lots of dust accumulated in the ducts and is blowing into the house. My wife has also seemed to get sick more frequently since we moved in. I was wondering if anyone has had experience with air duct cleaning? If so, how did it go? Did you notice any difference?