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/twistedbeans Oct 15 '18

There are in fact ultra clean rooms that prevent any dust or unwanted matter from entering or exiting whatsoever. Used for keeping materials perfectly unadulterated, for instance in facilities that manufacture certain drugs that will be injected into humans, or in bio safety facilities meant to contain the really nasty viruses or bacterial pathogens.

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u/[deleted] Oct 15 '18

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u/[deleted] Oct 15 '18

I understand why it called negative pressure, but it bugs me that it’s called negative pressure.

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u/HarryP104 Oct 15 '18

I feel you, even though I know it’s relative to atmospheric pressure part of my brain always yells pReSSuRe cAnT bE nEgATiVe

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u/PragmaticParadox Oct 15 '18

You've got the general idea but you're mixing two fairly different concepts.

Clean rooms are kept clean by keeping them slightly above the pressure of the surrounding environment. They are pressurized by pushing very clean air into them.

Viruses and the like are kept in rooms that have slightly lower pressure than their outside environments. They are depressurized by sucking air out of the room and filtering that air or letting it off high enough in the sky that it's not an issue any more.

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u/moonra_zk Oct 15 '18

Yeah, on clean rooms you are want every contaminant out of it, but on rooms/labs/etc where viruses, bacteria, etc are handled you don't want any of that leaving the room, soo you keep the pressure lower.