The Dirt On Dust Where does all that dust under your couch come from? It turns out that most household dust comes from outside — and may contain some pretty harmful stuff. How the toxins in dust get into your body depends on the size of the dust particle.
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The Dirt On Dust

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The Dirt On Dust

The Dirt On Dust

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  • <iframe src="" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
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Next, we're going to give you the dirt on dust. Even the most well-scrubbed homes will have some dust buildup somewhere, and the reason to remove dust is not just aesthetic. As NPR's Joe Palca reports, dust has some potentially harmful stuff in it.

JOE PALCA: As they used to say in Elizabethan times: How dost thou?

(Soundbite of vacuum cleaner)

PALCA: I tend to favor a vacuum. On the other hand, nature abhors a vacuum. But before we get into removing dust, let's talk a bit about what dust is and how it gets into your house.

Dr. PALOMA BEAMER (University of Arizona): Outdoor soil particles that come in on your shoes.

PALCA: Paloma Beamer is on the faculty of the University of Arizona in Tucson and something of a dustologist. Outdoor soil is one element in dust. Another is the tiny particles in air that float in when you open a window or door. And then there's the indoor component of dust.

Dr. BEAMER: Like pieces of your carpet fiber or your furniture, your bedding or anything like that that starts decaying.

PALCA: The indoor components also include certain bits of organic matter.

Dr. BEAMER: A lot of our skin flakes and dander off your pets and other insects or bugs that might be in the home.

PALCA: Now, as anyone who's looked under a sofa knows, there's dense dust and there's fluffy dust.

Dr. BEAMER: So 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.

PALCA: Beamer is interested in dust because it's one way people can be exposed to toxic substances. For example, for someone living near a toxic waste site, some of those chemicals can end up in house dust. The question is how much. In a recent paper in the journal Environmental Science and Technology, she calculates the proportion of dust that's from indoor sources compared to outdoor.

Dr. BEAMER: The indoor percentage would be around 34 percent, and then the two-thirds from outdoor comes both from soil tracked in and the outdoor air particles.

PALCA: But to understand the potential for exposure, it's also crucial to understand how dust can get into your body. Turns out, for dust, size matters.

Dr. ANDREA FERRO (Clarkson University): The big thing about particles and breathing particles is the size of those.

PALCA: Andrea Ferro is also a dust expert. She's at Clarkson University in Potsdam, New York. She says some of the particles are small enough that they can float in the air, and we can breathe them into our lungs. Others are larger and tend to sink more rapidly to the ground. One thing that's remarkable about dust is that it sticks around. Ferro says without vacuuming, it can stick around for a long time.

Dr. FERRO: And we're finding things like DDT in many indoor dust samples. We haven't had - you know, we banned that decades ago, but it's still there.

PALCA: In addition to breathing in dust though your nose, you can also swallow it. Duke University's Heather Stapleton is an environmental chemist. She says you may not be in the habit of licking the floors or carpets in your home, but some younger members of your household might be doing essentially that.

Dr. HEATHER STAPLETON (Environmental Chemist, Duke University): Being the parent of a six-month-old, I can't tell you how many times I look at my son and I see him with his hands in the mouth all the time, or picking up a toy and putting it in his mouth. So it's incredibly difficult to quantify what mass of dust you're actually exposed to and any contaminants associated with that dust. But it definitely occurs.

PALCA: Stapleton says it's really hard to estimate just how much exposure a person has to the chemicals in dust. But, obviously, reducing the amount of dust will reduce your exposure.

Dr. BEAMER: Keeping a well-dusted home, a well-vacuumed home will reduce the dust in your home the most.

PALCA: Paloma Beamer says you want to get a good vacuum, and if it has one, change the bag before it gets too full.

Dr. BEAMER: I think it's important to remind yourself to not just vacuum your floor, but also your upholstered furniture.

PALCA: Yeah. Oh, dear. OK. More work to do.

(Soundbite of laughter)

(Soundbite of vacuum)

PALCA: Joe Palca, NPR News, Washington.

(Soundbite of music)

INSKEEP: Dusting the globe. This is NPR News.

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