Dust comes from several sources and is difficult to eliminate completely. Increased dust could be a sign that it is time to change a dirty furnace or air conditioner filter or vacuum cleaner bag. Activities that produce dust (such as sanding) can also be a source an increase. Dust can also be introduced into your home through air leaks in ducts, or air infiltration through leaky doors and windows.
Change or clean your furnace and air conditioner filters once a month or according to the filter manufacturer's instructions. Temporarily seal the filter in place with metal-back duct tape. Write the date on the tape with a marker so your know when it was last changed.
Your clothes dryer should be vented directly to the outside. Inspect the vent duct. Make sure it is attached securely to the dryer. Check that it is clear of obstructions (e.g. lint). Check for holes that leak air. If vent duct is damaged replace it with a metal duct. The vent duct should be cleaned at least once a year. The Consumer Products Safety Commission additional safety tips for dryer vents .
Consider leaving your shoes at the door so you don't track outside debris-often the largest source of dust -into your house.
Sealing air leaks (Home Sealing) can help to reduce air infiltration that could be a source of dust.
Sealing duct air leaks, especially the return duct, can help prevent dust from being circulated throughout your house.
If you are concerned that dust is coming from your ducts please refer to Should You Have the Air Ducts in Your Home Cleaned? (an EPA publication) for information about duct cleaning.