Dust. It floats lazily through beams of sunlight, it settles gently on surfaces, and it tangles with other mysterious miscellany to create inanimate creatures beneath the couch–but where does it come from, and is it harmful? Scientists in Arizona reported a surprising answer to those questions in a report, “Migration of Contaminated Soil and Airborne Particulates to Indoor Dust,” which appeared in the ACS Environmental Science & Technology journal. The verdict? Most of indoor dust comes from outdoors, and it’s not always all that innocuous.
In the study, David Layton and Paloma Beamer found that over 60 percent of house dust originates outdoors. They note that household dust consists of a mixture that includes dead skin shed by people, fibers from carpets and upholstered furniture, and tracked-in soil and airborne particles blown in from outdoors. It can include lead, arsenic and other potentially harmful substances that migrate indoors from outside air and soil. This can be of special concern for children, who can ingest these substances by spending time on a dusty floor, or by putting dusty toys and other objects into their mouths.
They estimated that nearly 60 percent of the arsenic in floor dust could come from arsenic in the surrounding air, with the remainder derived from tracked-in soil.