Umar, the underwear bomber.

For those who don’t know it, the underwear bomber, Umar Farook Abdulmutallab, wore his pair of explosive underwear for 3 weeks straight before trying to detonate them while flying over Detroit in 2009. They didn’t go off, leaving him scarred for life. It’s quite possible that the nasty little mites that live in underwear stopped the underwear bomber. They are a main source of US allergens too.

Dust mite, skin, and pollen seen with a light microscope. Gimmie some skin.

If you’ve ever used an electron microscope to look at household objects, you’ll find them covered with brick-like flakes of dried out skin-cells: yours and your friends’. Each person sheds his or her skin every month, on average. The outer layer dries out and flakes off as new skin grows in behind it. Skin flakes are the single largest source of household dust, and if not for the fact that these flakes are the main food for mites, your house would be chock full of your left over skin. When sunlight shines in your window, you see the shimmer of skin-flakes hanging in the air. Under the electron microscope, the fresh skin flakes look like bricks, but mite-eaten skin flakes look irregular. Less common, but more busy are the mites.

The facial mite movie. They live on in us, about 1 per hair follicle, particularly favoring eyelashes. Whenever you shower, you shower with a friend.

Dry skin is mostly protein (keratin), plus cholesterol and squalene. This provides great nutrition for dust mites and their associated bacteria. In warm, damp environments, as in your underwear or mattress, these beasties multiply and eat the old skin. The average density of dust mites on a mattress is greater than 2500/gram of dust.^[1]  The mites leave behind excrement and broken off mite-limbs: nasty bits that are the most common allergens in the US today.

An allergy to dust shows up as sneezing, coughing, clogged lungs, and eczema. The most effective cure is a high level of in-home hygiene; mites don’t like soap or dry air. You’ve go to mop and vacuum regularly. Clean and change your clothing, particularly your undergarments; rotate your mattresses, and shake the dust out of your bedding. Vacuuming is less-effective as a significant fraction of the nasties go through the filter and get spread around by the vacuum blower.

As it turns out, dust mites and their bacteria eat more than skin. They also eat dried body fluids, poop residue, and the particular explosive used by Umar Farook, pentaerythritol tetra nitrate, PETN (humans can eat and metabolize this stuff too — it’s an angina treatment). The mites turn PETN into less-explosive versions, plus more mites.

Mighty mites as seen with electron microscopy. They eat more than skin.

There are many varieties of mite living on and among us. Belly button mites, for example, and face mites as shown above (click on the image to see it move). On average, people have one facial mite per hair follicle. It’s also possible that the bomber was stopped by poor quality control engineering and not mites at all. Religion tends to be at odds with a science like quality control, and followers tend to put their faith in miracles.

Chigger turning on a dime

larger than the dust mite is the chigger, shown at left. Chiggers leave visible bites, particularly along the underwear waste-band. There are larger-yet critters in the family: lice, bed bugs, crabs. Bathing regularly, and cleaning your stuff will rid yourself of all these beasties, at least temporarily. Keeping your hair short and your windows open helps too. Mites multiply in humid, warm environments. Opening the windows dries and cools the air, and blows out mite-bits that could cause wheezing. Benjamin Franklin and took air-baths too: walking around naked with the windows open, even in winter. It helped that he lived on the second floor. Other ways to minimize mite growth include sunlight, DOT (a modern version of DDT), and eucalyptus oil. At the very minimum, change your underwear regularly. It goes a long way to reduce dust embarrassing moments at the jihadist convention.

Dr. Robert E. Buxbaum, Sept 21, 2014. Not all science or life is this weird and wonderful, but a lot is, and I prefer to write about the weird and wonderful bits. See e.g. the hazards of health food, the value of sunshine, or the cancer hazard of living near a river. Or the grammar of pirates.