House Dust Nothing to Sneeze At

For millions of Americans, the world is a sneezy, wheezy place, filled with normally harmless substances that their bodies recognize as enemies. Of all the enemies, one is virtually inescapable: house dust.

“The predominant allergen is definitely house dust, there’s no question about it,” says Dr. Robert Overholt, an allergist in Knoxville, Tenn.

About 58.7 million Americans, about a quarter of the population, have some type of allergy. They sneeze or wheeze. Their noses get stuffy, runny and itchy. Many people with allergies have asthmatic reactions. They cough, wheeze and get short of breath as their bronchial passages narrow.

What makes lowly house dust such a plague to allergy sufferers is that just one speck contains a host of things that cause an allergic reaction – dust mites, human skin particles, animal dander, parts of cockroaches, mold spores, food particles and other debris.

The mighty mite

Perhaps the nastiest part of having dust bunnies around your house is that they contain dust mites, tiny critters measuring about 1/100th of an inch in length (smaller than the period at the end of this sentence). As many as 18,875 dust mites can live in 1 gram of dust, with the usual population being about 100 to 500 mites per gram, which is equal to the weight of a paper clip, according to the American College of Allergy, Asthma & Immunology (ACAAI).

A study in England showed 10 percent of the general population and 90 percent of people with allergic asthma have positive skin tests for allergy to dust mites. Studies in the United States suggest that at least 45 percent of young people with asthma are allergic to dust mites, according to the ACAAI.

There is no avoiding house dust and its little live inhabitants, Overholt says. Dust mites take up residence in our pillows, mattresses, carpeting, upholstered furniture and even books.

The more humid the environment, the better mites like it, too, he says. Dust mites grow best when humidity is greater than 40 percent. In Denver, Colorado, where it is very dry, you won’t find any dust mites.