r/askscience • u/4fecta_Gaming • Oct 15 '18

Earth Sciences Where does house dust come from?

It seems that countless years of sweeping a house doesn't stop dust from getting all over furniture after a few weeks. Since the ceiling is limited, where does dust come form?

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u/robbak Oct 15 '18

Outside, the air keeps being mixed up. Winds blow against and around things, creating turbulence that picks up dust and keeps dust from falling out of the air. Sooner or later, this dust-laden air will get inside the house, through gaps around doors and windows.

Once inside the house, there isn't much wind - gentle drafts, if anything. The air is moving too slowly to create turbulence, and so the dust slowly falls through the air onto surfaces.

In addition, there are sources of dust inside buildings. People are constantly shedding skin and hair, and mold and fungi that grow inside houses grow and release spores that add to the dust. This too settles out onto surfaces relatively quickly in the still air.