High concentrations of dust mite allergens are a significant risk factor for the development of allergies and related diseases such as asthma and rhinitis (hay fever). Eighty percent of children and young adults with asthma are sensitive to dust mites. And studies at the National Institute of Environmental Health Sciences (NIEHS) suggest that more than 45 percent of U.S. homes have bedding with dust mite concentrations that exceed a level equated with allergic sensitization.
Dust mites are microscopic creatures (smaller than 1/70 of an inch) that thrive in warm, dark, moist places with temperatures of 68° to 84°F and humidity levels at 75 to 80 percent. They thrive in bedding because that is where they find their biggest meals: They thrive on sloughed-off human and animal skin.
Under the microscope, dust mites appear as sightless, spider-like arachnids. They breathe through their skin, and while in dormancy, they are impervious to poisons, so insecticides are worthless if you choose to use them.
You can also find dust mites in dust ruffles and bed curtains (because they trap dust easily) and on feathers, furs, protein-based textiles, and other organic fibers. Polyester bedding is also a well-known haven for dust mites because it traps moisture from perspiration.
It's the feces and body parts from the dust mites that are the allergens, so simply killing the mites won't remove the allergen, although reducing populations is always a considerable help. To minimize mite populations, you need to make changes in your daily living and cleaning routines. While you may not be able to do all of these things, just implementing a few of these techniques will reduce the number of mites in the bedroom.
Direct sunlight kills dust mites, so hang bedding in the sun whenever possible. (Be mindful, though, that outdoor allergens can collect on bedding hung outside.)
Dust mites die when the humidity falls below 40 to 50 percent; use a dehumidifier if the weather is humid.
Wash bed linens once a week in hot water — the water temperature should be 130°F or higher — to kill mites.
Steam-cleaning carpets considerably lessens dust mite populations and deters population growth. A study in Glasgow, Scotland, found an 87 percent drop in the concentration of dust mites per gram of dust after carpets were steam-cleaned.
Vapor steam-cleaning (using a small machine that heats surfaces with dry steam) kills fungus, dust mites, bacteria, and other undesirables. This is a good way to clean bedding that you can't launder, such as mattresses. Vapor contains only 5 to 6 percent water (conversely, most steam cleaners use lots of warm water to clean), so the vapor steam doesn't contribute to a moist environment. Vapor steam deeply penetrates whatever it is cleaning, and it is great for upholstery, couches, carpets, and mattresses.
The natural lanolin in wool repels dust mites — another reason to buy wool bedding.
Studies at NIEHS found significant reduction of dust mites when allergen-proof covers were combined with properly laundered bedding, dry steam-cleaning, and vacuuming. Vacuuming alone didn't work as well as the combination of vacuuming with dry steam-cleaning of carpets and upholstery.
Buy a new pillow every 6 months (dust and dust mites live in pillows).
Eliminate wall-to-wall carpet (especially over concrete floors because concrete generates moisture/humidity). Decorate with washable throw rugs instead.
Freeze stuffed animal toys in the freezer (in a tightly closed plastic bag), and shake vigorously outside after removing them from the freezer. Or, wash stuffed toys often.
Keeping a bedroom clean is important for mite control. Use a HEPA vacuum in the room, and run a HEPA air filter near the bed when the room isn't occupied. Make sure the bedroom curtains or window coverings are washable. Horizontal venetian blinds can be wiped clean with a damp cloth (but they do collect a lot of dust), and if you have shades that can't easily be washed, they should be of a type that's easily vacuumed. Be sure to avoid fuzzy fabrics and bed linens and fluffy pillows; they'll attract and capture dust.
Cut the clutter. It is very hard to dust well when surfaces are covered with dust-collecting objects. Rough, raw pine and fabrics are also hard to keep free from dust. If you can't bear to get rid of certain possessions, use covered storage containers for papers, magazines, and other bric-a-brac to reduce dust-catching surfaces.