Dust mites are not insects; they're more closely related to spiders, chiggers and ticks. They're not visible to the naked eye; up to 0.3 mm (1/100th of an inch) in length, which is smaller than the period at the end of a typed sentence.
. . They feed on the dead skin that falls off the bodies of humans and other animals and on other organic material found where they live. Dust mites are second only to pollen in causing allergic reactions. When dust mites grow, they shed their skin. The shed skin and feces are what cause allergic reactions in people.
. . They do not live in air ducts... they need about 70 percent relative humidity or higher to live, and they need food.
. . Your bedroom should have a hardwood, tile or linoleum floor instead of carpet. Dust mites can grow rapidly in carpet. Their droppings contain left-over enzymes which the mites use to digest the skin dust. It is these enzymes which are the most important part of mite dust in causing asthma and other allergic diseases. Every time someone walks over a carpet, mite dust is spread into the air, and will take 2 hours to settle. Babies and young children crawling on the carpet are surely especially at risk.
. . The geometric mean mite count in the BRE study was 186 mites/m2 in the living room carpet and 174 mites/m2 in the bedroom carpet, with a marked seasonal variation due to temperature and humidity changes. As many as 18,875 mites were counted in a gram of dust (the weight of a paper clip), each producing up to 20 faecal pellets per day. The pellets are about the same size as our red blood cells.Old mattresses easily carry up to a million live dust mites. Given enough food supply, each mite can process and package four faecal pellets per day. With four million allergenic particles disturbed when people are active in bed, it is no wonder there is not only shortness of breath but an associated wheezing and hard breathing!
. . House dust mites cannot drink. They obtain water partly from their food but the bulk of the water needed is obtained by a mechanism using hygrophilic (water-loving) crystals in their armpits. These finely structured crystals can obtain enough water for the mite when the relative humidity in the air is above 60 per cent. The mite must tone down its activity if the relative humidity drops below this.
. . In England, where 95 per cent of homes studied have wall-to-wall carpets, about one-third of the children studied have confirmed dust mite allergy. However, in Scandinavia, very few households have carpet and almost none of the children studied have mite allergy.
. . Bath or shower before going to bed. Do not eat on the bed or on soft furnishings. Fixed carpets, especially those with thick underlay, provide excellent protection for the dust mites. Even the strongest vacuum cleaners cannot produce enough draft in the depth of the carpet piles to dislodge them. Rugs are the best way to go.
. . Soft toys should be frozen in the freezer (this breaks down the hygrophilic crystals in the dust mite's armpits) and then followed by sunning for six hours or more every two to three months.