April is the traditional month for spring cleaning: opening doors wide for the first time in months, polishing things till they gleam, possibly beating on rugs with some kind of stick or club? In honor of this season of good housekeeping, we've asked Jeopardy! mastermind Ken Jennings to help us out with a little mental spring cleaning. He'll be dusting away some persistent around-the-house myths and spraying the sweet-smelling Lysol of Truth over all your remaining brain clutter.

The Debunker: Is Most Household Dust Really Human Skin?

Do you feel "comfortable inside your skin," as the saying goes? Well, just wait a few hours. You may feel like your skin is a permanent part of you, but in fact, the body is constantly replacing its billions of skin cells as they wear out. Every hour, you lose over half a million dead skin cells. In fact, eight hundred of the little guys just flaked off while were reading this sentence.

So it seems plausible, right, the common claim that as much as 80 percent of household dust is human skin? There is organic material in dust—all that discarded "you" has to go someplace—but it turns out that there's so much tiny stuff floating around your room (about 10 million particles in every cubic meter of household air!) that skin isn't even a drop in the bucket. In 2009, Paloma Beamer of the University of Arizona catalogued household dust for the journal Environmental Science and Technology, and found that two-thirds of it blows in from outdoors: dirt tracked in on floors, as well as particulate matter from the air. The other third is mostly carpet fiber. Not much skin.

There's a similar scare statistic that gets passed around about mattresses. In 2000, The Wall Street Journal quoted academics and industry experts to the effect that a mattress will double in weight after just ten years of use, as a result of the accumulated carcasses and poop of tiny "dust mites." Let's get the nightmare fodder out of the way: yes, "dust mites" are real. They're microscopic arachnids of subclass Acari that live by chowing down your dead skin. But it's not true that there's a hundred pounds of them living inside your Posturepedic. The researcher cited in the article later complained to Cecil Adams that he had never said any such thing, and that there's no academic basis whatsoever for this factoid. It's time to send this stuff to the dustbin of history.

Quick Quiz: The band that sang "Dust in the Wind" formed in 1970 in which U.S. state capital?

Ken Jennings is the author of six books, most recently his Junior Genius Guides, Because I Said So!, and Maphead. He's also the proud owner of an underwhelming Bag o' Crap. Follow him at ken-jennings.com or on Twitter as @KenJennings.