May 22, 2001 (San Francisco) -- Invisible, breath-robbing, spiderlike creatures are nesting in the bedding of some 23 million American homes, many of them low-income homes, according to new research released here at an annual meeting of lung specialists.
Even though you can't see them, dust mites exist year-round in virtually every type of housing. They live off human skin flakes, which are constantly sloughed off. And they rapidly reproduce in moist environments.
Many studies already have established the connection between mites and asthma and allergy attacks, but Darryl Zeldin, MD, of the National Institute of Environmental Health Sciences, conducted the first nationwide survey looking for evidence of the pesky critters lurking between the sheets. He presented his results at the International Conference of the American Thoracic Society.
Zeldin and colleagues sampled bedding in 831 homes where about 2,500 people lived from 75 different locations around the country. In addition to vacuuming up dust samples, the researchers collected environmental data and information about the study participants' race, income level, and health status.
It turns out that some 86% of American homes have detectable levels of dust mite allergen, but more importantly, around 23% of homes have enough of the irritant to trigger respiratory problems. Since mites are drawn to humidity, Zeldin says you're four times as likely to have mites in the Northeast as in the West where it's drier.
In addition, low-income families' homes have a higher level of dust mites than previously thought. "Homes where the annual income is less than $30,000 per year are about twofold more likely to have dust mite allergens in their beds, and about sevenfold more likely to have cockroach allergen in their beds," says Zeldin.
The researchers found cockroach allergen in about 6% of American homes. They also have been linked to asthma.
"In environmental science, we're very interested in environmental justice, the lower socioeconomic class families are disproportionately affected," says Zeldin.
Other risk factors for dust mites are living in single-family homes, high bedroom humidity, mildew odor in the bathroom, and living in a home built before 1978.
Your chances for sharing your house with cockroaches and their accompanying allergen go up if you live in a low-income environment where food debris is present.
From their study, the researchers conclude that high dust mite allergen levels are a problem in a significant number of U.S. homes. "This information can be used to identify homes and individuals that are at greatest risk of exposure so that researchers can better target their prevention and intervention efforts," says Zeldin.
So what can you do about dust mites? Some of the fixes are relatively inexpensive.
Zeldin says the most effective fix is to wrap bedding, including the box springs, mattresses, and pillows, in zippered, allergen-proof casings. These casings can be bought at any linen store and cost less than $50.
Here are some additional tips to keep the mites from getting mightier:
- Clean your bedding frequently and thoroughly in water temperatures of at least 130°.
- Use dehumidifiers and air conditioners to remove airborne allergens and to control indoor moisture.
- Because dust mites prefer living in upholstered furniture and in carpeting, consider leather furniture and hardwood floors as an alternative. If not, regularly vacuum and steam clean upholstered furniture and carpet.
- A less expensive option is to clean upholstered furniture and carpet regularly with a vacuum cleaner with HEPA filters, which pick up particles as small as a dust mite.
- As for man's best friend, keep in mind that dogs and cats are mite magnets. Consider keeping pets out of the bedroom and washing their bedding thoroughly.
The researchers also stress that mites aren't the only household respiratory risk factors. Other bacterial substances known as endotoxins also can have an irritating effect on the lungs. More research is needed on their role.