MADELEINE BRAND, host:
I'm Madeleine Brand, and this is DAY TO DAY.
Back in 1988 a little-known medical study suggested something completely counterintuitive: Vacuuming your home may actually make your allergies worse. The answer has to do with a little-known culprit, the dust mite. I spoke earlier with Dr. Sydney Spiesel, who's on the faculty of the Yale Medical School and writes on medical news for the online magazine Slate.
Dr. SYDNEY SPIESEL reporting:
Dust mites are these little microscopic creatures. They have eight legs like spiders instead of six legs like insects and they don't fly, but these are tiny, tiny, tiny creatures which I guess is why they're called mites. In fact, they're microscopic. The way you can see them--in fact, we all have seen them--is that if you were to slam your hand down on a mattress in a room where sun was streaming in the window, you'll see these little particles kind of dancing around, floating in the air. And those are either living or the dead bodies of dust mites.
BRAND: So we all thought that that was just dust circulating in the air, but it's actually living, breathing, feasting dust mites.
SPIESEL: Feasting, actually, on little tiny flakes of skin that we all shed. That's what they live on. I think they're one of the two most serious causes of allergies in humans.
BRAND: So we have heard that keeping a scrupulously clean house will help with allergic reactions, and this study disproves that to some extent.
SPIESEL: Yes, this is good news for people who are not so compulsive about keeping their houses perfectly clean. The man who did the study decided to find out how much vacuuming it would take to clear the mites out of a carpet, a perfectly plausible question. And so he kept vacuuming and vacuuming and vacuuming, and what he found was that other dust ingredients were reduced, but the mite count really didn't drop. In fact, ultimately it kept getting higher and higher toward the end of the study.
BRAND: Higher and higher. Why is that?
SPIESEL: It turns out that there's another kind of mite called the cheyletus mite which is predatory on dust mites. The cheyletus mite eats the little dust mites. And they don't hold on--the cheyletus mite doesn't hold on as tightly as the dust mites do to fibers. So we're vacuuming out the predators, which are our friends, and we're leaving behind the dust mites which are our--well, I wouldn't like to call them enemies, but they're not nice to us. But maybe the answer is what in fact I hate to say but allergists have been saying a long time, which is it's probably better not to have carpets, that vacuuming is something that's long been known to be a problem in the houses of people with allergies because mostly what vacuuming does anyway, even without the increased number of dust mites, is it just raises the mites up from the carpet and puts it in the air and puts these little bodies or fragments of the bodies in the air and they hover there for a long time for people to inhale.
BRAND: Well, what about bedding? 'Cause as you say, that's where a lot of them live.
SPIESEL: Well, bedding is also a problem because, you know, when you throw yourself down on the mattress, you can see those little dust particles, which, as I say, are dead bodies of mites or living ones; you see them floating up. So for people who have serious allergies, what we sort of recommend is encapsulating them. Just put a vinyl encasement around your mattress so that the bugs, these tiny little mites, are caught inside the mattress. And then put a mattress pad, 'cause who wants to sleep on plastic, that's filled with artificial fiber instead of natural fibers. One of these things about these little creatures is they have better taste than we do often and they really like only natural fibers; they're not happy in artificial fibers. Sadly, it also means for many people getting rid of that wonderful, wonderful down pillow that they just love to put their heads on.
BRAND: Dr. Sydney Spiesel is a pediatrician in Connecticut and he writes on medical news for the online magazine Slate.
And DAY TO DAY returns in a moment. I'm Madeleine Brand. Transcript provided by NPR, Copyright NPR.