They are generally found on the floor and other surfaces, until disturbed (by walking, for example). It could take somewhere between twenty minutes and two hours for dust mites to settle back down out of the air. Dust mites are a nesting species that prefer a dark, warm, and humid climate. They flourish in mattresses, bedding, upholstered furniture, and carpets. Their feces include enzymes that are released upon contact with a moist surface, which can happen when a person inhales, and these enzymes can kill cells within the human body. House dust mites did not become a problem until humans began to use textiles, such as western style blankets and clothing. Furniture
Furniture with wooden or leather surfaces reduces the dust mite population. Bed linen
Hot tumble drying a bed linen for 1 hour will kill 99% of mites therein.Weekly changing the bed linen reduces the risk of exposure to dust mites.Cotton covers not covered with complete mattress covers are very likely to become colonized by bacteria and molds; they must be cleaned periodically (at least every second to third month).
Symptoms
Dust mite allergy symptoms include:

Cough
Facial pressure and pain
Itchy, red or watery eyes
Itchy nose, roof of the mouth or throat
Nasal congestion
Postnasal drip
Runny nose, sneezing
Swollen, blue-colored skin under the eyesIf the dust mite allergy contributes to asthma:

Audible whistling or wheezing sound when exhaling
Bouts of coughing or wheezing that are worsened by a respiratory virus such as a cold or the flu
Chest tightness or pain
Difficulty breathing
Trouble sleeping caused by shortness of breath, coughing or wheezing

Cross-reactivity to shellfish allergy
Tropomyosin, the major allergen in dust mites, is also responsible for shellfish allergy. Exposure to inhaled tropomyosins from dust mites is thought to be the primary sensitizer for shellfish allergy, an example of inhalant-to-food cross-reactivity. Epidemiological surveys have confirmed correlation between shellfish and dust mite sensitizations. An additional confirmation was seen in Orthodox Jews with no history of shellfish consumption, in that skin tests confirming dust mite allergy were also positive for shellfish tropomyosin. In addition to tropomyosin, the proteins arginine kinase and hemocyanin seem to have a role in cross-reactivity to dust mites. Prevention
House dust mites are present indoors wherever humans live. Positive tests for dust mite allergies are extremely common among people with asthma. Dust mites are microscopic arachnids whose primary food is dead human skin cells, but they do not live on living people. They and their feces and other allergens that they produce are major constituents of house dust, but because they are so heavy they are not suspended for long in the air.