by Nick Gromicko, CMI®
Dust mites are microscopic arachnids that thrive indoors in warm, moist places, such as the insides of pillows and mattresses. They feed on dead skin that is regularly shed by humans and their pets. The harm posed to building occupants by dust mites is slight compared to other minuscule bed-dwellers, such as bed bugs. Yet, unlike those blood-sucking parasites, dust mites live in virtually every home and in large numbers. Due to their small size, access to copious quantities of food, and an insatiable desire to breed, dust mites can number 100,000 in just one square yard of carpet. They are a known allergen and can create allergic reactions in prone individuals, so it’s important to learn dust-mite detection and population-management strategies.
Size and Identification
At just 0.42mm in length and 0.25mm to 0.32mm in width, typical dust mites are barely visible against a dark background in normal light, and a microscope is required to clearly see their features. Creamy blue in color and rectangular-shaped, they have eight hairy legs, and no eyes or antennae. While their presence can be confirmed microscopically, testing is an unnecessary expense because they virtually always show up in tests.
Dust mites are medically significant because their feces contain a protein that can cause allergic reactions in certain individuals. The following are some of the more common allergy symptoms experienced by sufferers:
- asthma and difficulty breathing;
- in a child, frequent upward rubbing of the nose;
- hay fever;
- runny nose;
- itchy, red or watery eyes;
- nasal congestion;
- itchy nose, roof of mouth and/or throat;
- post-nasal drip;
- facial pressure and pain;
- cough; and
- swollen, blue-colored skin under the eyes.
While there exists a genetic predisposition to allergic reactions, they can also develop over time, especially from childhood exposure. Eighteen to 30% of Americans are allergic to dust mites' feces, and almost half of all American homes have dust mite allergen levels that are high enough to create sensitivity in people who were not previously allergic. A doctor can confirm a dust mite allergy using skin or blood tests.
Eradication and Management
Disodium octaborate tetrahydrate powder is used to eradicate house dust mites. Non-chemical measures, such as limiting the availability of food, adjusting living conditions, and removing or killing the critters themselves can also be effective. Specifically, homeowners can practice the following management practices:
- Reduce humidity levels. Studies have shown that the use of an air conditioner or electric blanket can dehumidify sufficiently to reduce the number of dust mites found in the home.
- Dust. Before you vacuum, dust surfaces with a damp cloth, and be careful not to scatter the dust.
- Vacuum. The vacuum is the most important tool in the homeowner’s dust mite arsenal. Thorough, regular vacuuming of carpets, furniture, textiles and other home furnishings will keep dust mite populations in check. Use a vacuum with a HEPA filter to avoid re-dispersal of dust into the home. The person with the allergy should not be the one performing the cleaning.
- Use air purifiers. A HEPA filter air purifier will reduce the level of airborne dust mites. The effectiveness of these products is limited, however, as dust mites are generally not airborne.
- Isolate pets. Pets create large amounts of dander, which is a food source for dust mites. Locate these pets’ sleeping quarters far from your own and in an area that can be cleaned easily, such as on washable hardwood or vinyl floors. If possible, avoid the adoption of excessively furry pets, and groom them regularly outdoors.
- Isolate fabrics. Move all upholstered furniture, clothes, draperies, carpets and rugs away from the allergic individual’s sleeping quarters.
- Reduce air infiltration. Open doors and windows can allow the entry of pollen, which serves as food for dust mites and is itself an allergen. Damp summer air can also flow indoors and increase humidity levels, which encourages the spread of dust mites.
- Launder bedding. Research has shown that laundering with any detergent in warm water (77° F) removes nearly all dust mites from bedding. Ten minutes in a household clothes dryer at high temperatures will kill all dust mites in bedding.
Exaggeration and fear-mongering have spurred an entire industry of detergents, air filters and other products that purportedly protect building occupants against dust mites, which are harmless to those who are not allergic. These products often don’t work as advertised and are rarely as effective as the simple measures described. Do your research before buying into clever marketing, and be sure to hire an IAC2 certified InterNACHI inspector if you have any worries about household pests or air quality.
In summary, dust mites are small, house-dwelling critters that can create allergic reactions in sensitive individuals. Their numbers can be managed through relatively simple strategies.