These little bugs are so small that between 100 and 500 individual mites live in a single gram of dust. Despite their size, dust mites cause some big problems. Or more specifically, their feces do.

Related to spiders and ticks, dust mites live in fabrics like bedding and carpeting that collect dust. While we used to believe that people were allergic to dust, researchers now know it's not the dust itself, but the mites that live in it that cause the problem. Dust mite droppings (feces) contain a protein that is an allergy trigger for the majority of allergic individuals. And these mites live everywhere dust accumulates, particularly in bedding, upholstered furniture, carpeting and stuffed animals. They grow best where it's warm and humid. About the only places they don't flourish are where it's very dry or the altitude is more than 3,000 feet above sea level. Mites live on a diet of skin scales naturally shed by humans, and each mite produces between 10 and 20 waste pellets each day. Each egg-laying female can increase the population by 25 to 30 mites every three weeks.

These mites are no danger to nonallergic people because they don't bite humans or spread disease. But their numbers have increased dramatically in the past 20 to 30 years, especially during winter months, as more focus has been spent on building energy-conserving homes in which ventilation is limited and temperatures tend to be warmer. Here's how to take the might out of dust mites:

Wage battle in the bedroom
In most homes, the highest concentration of dust mites is in the bedroom, where they love to get cozy in mattresses, pillows and carpeting. The bedroom also happens to be a place that you spend a lot of your time. When you lay down to sleep, you bring your nose within inches of some of the most popular gathering places for mites. Dust mite proteins are reasonably heavy particles, so they only stay airborne for a short while after you stir them up. If you shift your position on your mattress, a large quantity of these proteins can drift into the air just above your mattress surface, which is the air you breathe during the night. Making adjustments to reduce exposure to mites in your bedroom and especially your bed can be your most powerful way to fight dust mite allergy.

• Wash all bedding — including mattress pads, comforters and blankets — in hot water every seven to 10 days.



• Consider covering mattresses, box springs, and pillows in allergen-proof encasements, so the mites and their debris can't pass through. These mattress and pillow covers are made with tightly woven material. They have been found to reduce dust mite allergen in the air, but a measurable improvement in asthma symptom severity has not been seen in several studies that have attempted to show such a benefit. However, many experts still believe that these covers may be worth their modest cost.



• Keep a bedspread on your bed all day to collect dust, but carefully remove it from your bedroom (without shaking it) before you go to sleep.



• Avoid feather or down pillows. Instead, use polyester fiber-fill such as Hollofil or Dacron. Dust mites like synthetic pillows as much as feathers or foam, but synthetic pillow can be washed. No matter what you use, all pillows should be encased in allergen-proof covers.



• Don't use fuzzy blankets unless they can be regularly washed. They tend to collect more dust than blankets with a thin weave. Other dust collectors include stuffed animals, wall-to-wall carpeting, rugs that are not easily washable, and bed canopies. These items should be removed from the bedroom or avoided altogether.

Dry up
Mites like it warm and moist, so dehumidifying your home can help. Air conditioning helps reduce humidity, but you may also want to invest in a dehumidifier, especially if you live in a southern climate. Dust mites do best when the relative humidity is above 55 percent, and grow poorly when it's below 45 percent. When indoor temperatures are close to 80° F, humidity should be lowered below 40 percent. Meanwhile, clean your air-conditioning filters every month.

Wooden it be nice
Big, overstuffed furniture provides the perfect comfort zone for dust and mites. So if you're shopping for new furnishings, choose sleeker, pared-down wooden products with less stuffing. Whenever possible, replace wall-to-wall carpeting with wood or sheet-goods flooring and with area rugs that can be laundered easily. Of course, you'll need to use dust-removing polishes on wood furniture and floors.

The only good mite is a dead mite
Poisoning of dust mites with benzyl benzoate (Acarosan) dry foam carpet and furniture cleaners once every six months may help if you do not remove rugs.

Think twice before filtering them out
Installing air cleaners and air filters to remove dust is a costly solution that may not be worth the investment. Air cleaners are available as attachments to your heating system or as portable units that can be moved from room to room. The most effective ones have high-energy, particle-arresting (HEPA) filters capable of trapping very small particles. Others use electrical charges, static electricity or ionizers to trap particles. None work well enough to substitute for other steps you can take to cut down on indoor allergens. Air cleaners that generate ozone gas have no effect on allergens in the air and may worsen allergy symptoms because the ozone they emit can irritate the respiratory system.

Avoid panic with tannic
No one is able to completely eliminate mites from a home. If you want to do everything you can to prevent dust mite allergy, it may help if you repeatedly treat places where dust mites gather with a substance (tannic acid) that chemically changes the protein that is the source of dust mite allergy so it can no longer act as an allergy trigger. Try treating carpets and furniture with a spray containing tannic acid.

This treatment may not help control dust mite allergy, probably because it is difficult to use it frequently enough to provide a noticeable benefit. Tannic acid must be regularly reapplied because it does not kill mites, and mites will quickly produce new feces pellets.