It's a widely repeated factoid that dust consists primarily of human skin. For instance, one can find this piece of information in the first paragraph on the
wikipedia page about dust. But Paloma Beamer, a dust expert at the University of Arizona, disputes this claim.
From NPR.org:
Beamer says there are really only two places dust can come from: outdoors and indoors. We are an important part of the process of getting the outdoor stuff indoors. We bring it with us when we enter a house — through "soil particles that come in on your shoes," says Beamer, or tiny particles suspended in the air when we open the door and walk in.
Then there's the indoor component of dust. "Like pieces of your carpet fiber or your furniture, your bedding, or anything like that that starts decaying," she says. Then there are organic contributors. "Skin flakes and the dander off your pets, and other insects or bugs that might be in the home."
Now, as anyone who's looked under a sofa knows, there's dense dust and there's fluffy dust.
"A lot of the fluffy things, I think, tend to do more when you get a lot of fibers. In my house, it comes from cat hair," Beamer says.
Beamer's interest in dust stems comes from her effort to measure people's exposure to toxic substances. In a recent paper in the journal Environmental Science and Technology, she calculates the proportion of dust that's from indoor sources, compared with the amount from outdoor sources. She figures that one-third comes from indoor inorganic sources like carpet fibers. "Two-thirds comes from both soil tracked in, and the outdoor air particles," Beamer says.
I'm inclined to think Beamer is right. I find it hard to imagine that the volume of dust in my house comes primarily from the dead skin cells of my wife and I.
Comments
Even that seems highly suspect, though. Numerous as people are, they make up a rather small percentage of the total amount of material on the earth's surface, so it would be rather amazing if they could produce more dust than everything else.
Based on what I get when I sweep, I'd say most of the dust in my house is made of cat fur and bits of cat litter.
And we use Afrosheen so we don't have to smell like nada.
Do skin particles contain DNA? if so, in theory, i'd visit another person's house and then THEIR skin would get on me and thus their DNA would be on me...
Dan
http://www.sharefile.com
I think he might have been onto something there.
(Quoting from memory here....) '"By no means," replied the Funambulist, with the zeal that characterises his kind. "We assert that the exhaled moisture in human breath has raised the sea by a precisely equal amount."
It's a great book. That last bit reminds me that I've also heard it stated as fact that the water we city-dwellers drink has all passed through the human body several times.