Why is my home so dusty?

If you have a fairly good (rated) filter in your hvac system it is unlikely that dust is entering your home from your supply registers. Many homes are equiped with a variety of exhaust fans.  These include the kitchen exhaust, all of the bath fans, and your cloths dryer.  Running these fans frequently puts some homes into a negative pressure condition.  (more air leaving the home). This may be allowing dust from outdoors to enter through windows, doors, and any other gaps in the building envelope. ...