The source of dust was the subject of a recent study by Arizona scientists. Surprisingly, Science Daily reports that most of our indoor dust comes from outdoors.

Household dust is made up of a conglomeration of dead skin cells and fibers from carpets and upholstery (inside sources) as well as tracked in soil and airborne particles blown in from outdoors (outdoor sources). In fact, using a computer model that tracks distribution of outdoor contaminants into residences, the scientists found that over 60 percent of house dust originates outdoors.

What's most disconcerting is that much of the particulate matter brought into the home from outside is dangerous, including lead, arsenic, and other substances that make their way inside from outdoor air and soil. This is especially concerning if there are young children in the home, who may ingest these substances by putting dust-contaminated toys in their mouths.