Combating Dust Mite Allergies

An estimated 60 million Americans suffer from allergies. Even in tiny amounts, house dust, which is a collection of debris from many sources including fabric fibers, human skin scales, human and animal dander, bacteria, cockroach parts, mold spores, food particles, and organic and synthetic materials, can set off symptoms. House dust alone does not cause problems. Rather, the most serious offenders are the "house dust mites," whose particles and fecal waste are the main causes of year-round problems.

House dust mites are diverse small arthropodsthat are microscopic--1/4-1/3mm long, about the size of a sharp pencil dot. The only harm they cause is to those who are allergic to them, sparking the typical symptoms of allergy--sneezing, sniffling, itchy and watery eyes, scratchy throat, stuffy nose, eczema and rash. House dust mites have also been implicated in asthma, causing wheezing, coughing, and shortness of breath. Susceptibility to house dust mites is increasing as people spend more time indoors. Newer houses are more air tight than older constructions are contributing to increased dust mite allergies.

House dust mites live all over the world. Mites need food, heat and humidity to thrive. Their diet includes human skin scales, fungi growing on skin, molds, insect bodies or fragments, pollen grains, bacteria, plant material and house dust. Optimum growth conditions are 20-25C and 70-80% humidity.

Dust mites are hardy creatures who live where skin is most prevalent. They can be found in old clothing, blankets, upholstery, heavy curtains and stuffed animals.

Carpeting is susceptible to dust mite infestation, especially long, loose-pile carpets, where food and moisture can accumulate and mites can burrow deep into the fibers, protecting themselves from vacuum removal. Bed mattresses and pillows (particularly foam and feather) provide the ideal environment for mites. Typically, 2-3 million dust mites reside in mattresses and box springs.

House dust mites have nothing to do with cleanliness or the presence of animals in the home. More likely, the factors contributing to their presence are humidity and the amount of fabric placed in susceptible areas.

One gram of house dust contains an average population of 100-500 mites, with the possibility of thousands being present. Egg-laying females add 25-30 new mites every three weeks. Each mite produces about ten to twenty waste particles a day. Mite fecal pellets are so tiny and light that they float easily into the air when disturbed by someone walking on carpet, sitting in an upholstered chair, rolling over in bed, or vacuuming or dusting. It is inhalation of these pellets that causes problems in the mite-allergic person, and even after the mite dies, its fecal particles remain in the home and its disintegrating body parts are still allergenic and easily airborne.

So if you are one of the more than 60 million people suffering from dust-related allergies, what can you do to help protect yourself? Quite simply, you must avoid the allergen, and the best way to accomplish this is to modify the home environment, particularly the bedroom.

Following are tips to get you started:

1. Use cotton, zippered, dust-proof, hypoallergenic covers to encase pillows, mattresses, and box springs. Most mites are in the bedding, and this encasement cuts off their food supply.

2. Use washable blankets, spreads and polyester or Dacron pillows. Avoid feather pillows, down or padded comforters, wool blankets and chenille spreads.

3. Launder ALL bedding and stuffed animals weekly. Use hot water (130-158) and dry in the hot cycle. Mites can survive in warm water. Cold water will kill only 50%. Dry cleaning also kills dust mites.

4. Replace heavy, lined drapes with shades or blinds. Lightweight, washable curtains can be used.

5. Use an upstairs bedroom, if possible.

6. Keep indoor moisture low. Ideal indoor humidity is between 30-40%.

7. Ventilate the bathroom after taking a shower, and always keep the bathroom door closed.

8. Avoid humidifiers and vaporizers. They create a favorable environment for dust mites.

Long-term solutions to dust mites are those changes that reduce bedroom dust and relative humidity:

1. Remove all carpeting and pads. Install hardwood or vinyl flooring (dust mites will not live on these), and use washable area rugs. If you insist on carpeting, use short, tight-piled carpets.

2. Install floor insulation vapor barriers, where feasible.

3. Remove upholstered furniture from the home. Use wood, leather, or vinyl furniture instead.

4. Install H.E.P.A. air filters in the central air/heating system . Use a portable air filter to remove dust, smoke and pollen from the air.

5. Install vents in the bathroom. A primary source of moisture is shower steam from unvented bathrooms.

Chemical solutions are not usually helpful in controlling dust mites.

To rid the home of dust mites, heat may be applied. Carpets can be treated with superheated steam. Laundry can be tumble-dried. Direct sunlight exposure, autoclaving, and dry heating with electric blankets may also be useful.

Pesticides are not an appropriate alternative for dust mite control. The concentrations that can kill mites are also toxic to humans.

Because dust mites are so pervasive, identifying a dust allergy can be difficult. Early morning congestion can be one sign of a dust allergy. If you have allergies that persist year-round and you think they may be dust-related but the control measures specified here does not improve your situation, consult an allergist. To obtain relief from severe allergies, you may need to supplement your environmental control with medication and allergy shots.






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