House dust mites, whose technical names are Der-matophagoides pteronyssinus and Dermatophagoides farinae, are microscopic insects that are relatives of the spider family. These tiny creatures are found throughout the world and live on a diet of sloughed human skin cells. An important component of their survival is a requirement of at least 45% relative indoor humidity. The primary reservoirs for dust mites are pillows, mattresses, bedding, upholstered furniture, and carpeting. The primary allergens of dust mites are proteins found in the body and fecal pellets of these insects. These allergenic mite proteins are bound to dust particles that are relatively large and heavy, preventing them from staying airborne for prolonged periods of time. Therefore, most of the expo-sure that occurs to dust mites occurs while an individual is lying in bed or on upholstered furniture.
While it is very helpful to minimize surface dust in a person’s home by vacuuming furniture and carpeting, this will not eliminate dust mites in a person’s bed or in furniture cushions. This is best accomplished by placing plasticized cloth encasings over the pillow, mattress, and box spring and washing all linens in hot water (130°F). Encasings that are labeled “hypoallergenic” but do not contain a plastic membrane will not effectively reduce exposure to allergenic mite proteins. If a person likes to lie down or sleep on couches and chairs, leather or vinyl upholstery is far preferable to cloth. High-efficiency particulate air (HEPA) filters have not been shown to reduce indoor dust mite levels or symptoms of mite-induced rhinitis.
High-efficiency particulate air (HEPA) filter
A filter specially designed to remove greater than 90% of small (1 micron) airborne particler-