Ever wonder where those small-and-furries come from? Believe it or not, environmental scientists have been trying to pick apart this mystery for years. Turns out the average dust sample can contain anything from insect fecal matter and fungal spores to lawn chemicals and heavy metals—and most of it walks right in through the front door. It's enough to induce a sneezing fit in even the hardiest of humans.
Spores and Germs
Allergy- and asthma-aggravating mold spores thrive in dusty places that are also warm and humid. It's unclear how long cold and flu germs survive, but dead bacteria throw off endotoxins, another lung irritant.
More than 100 toxins have been found in household dust: PAHs (car exhaust, tobacco, barbecue grills); PBDEs (fire retardants); phthalates (plasticizers); and phased-out but still extant PCBs, DDT, and 2,4-D (herbicide).
Natural and Industrial Poisons
They'll never entirely go away: We mean things like arsenic, a by-product of burning coal (and of volcanoes), and lead, an enduring legacy of leaded gas and paint. Toxins that linger in soil and dirt linger in dust, too.
Moth wings, cockroach legs, and rodent, pet, and dust-mite feces are all part of the world around us—maybe just 2 feet away. Ask anyone allergic to the castoffs from mites, which thrive in humid rooms and unaired beds.
Dander, Lint and Hair
Skin flakes, hair and pet fur, animal dander, carpet and fabric fibers, pollen, and even greasy food bits are united with all the other dust ingredients by static electricity and propelled—under the bed and elsewhere, of course—by air currents.
They're undeniably useful in manufacturing but potentially dangerous when inhaled—we're talking cadmium, copper, nickel, and lead. Toxic metals are found in higher concentrations in dust than in garden soil, according to the EPA. Mercury used in some light switches and thermostats may be to blame.