An estimated 20 million people in the U.S. are sensitive to dust mites and about 84% of all households have dust mites above detectable levels. Dust mites are virtually everywhere and can cause some really unpleasant symptoms like a congested or runny nose, sneezing, swollen watery eyes, and even eczema in people allergic to them. If you are allergic to dust mites, you probably wonder, what you can do to control dust mites in your house and especially your bedroom.
Where do dust mites live? High levels of live and dead dust mites, their body parts, and feces can be found in all places where their main food source, the thousands of skin cells we shed every hour accumulate. This includes in particular our mattresses, pillows, comforters and blankets, carpets, fabric upholstered furniture, and plush toys. Since we spend up to a third of our life in our bed, our bed and bedroom tends to have a high concentration of mites and their allergens.
Dust mites like it humid. They don’t drink water, but rather extract water from their environment. This means that if the environment is too dry, they dehydrate and die. The minimum relative humidity they need to survive depends on the temperature. That is, the warmer the environment, the higher the required minimum relative humidity (RH) they need to survive.(from 55% RH at 15°C to 73% RH at 35°C for the species Dermatophagoides farina1). It is important to note that some places (e.g. mattresses and carpets) tend to be more humid then others.
Here are some specific measures to control dust mites in your bedroom:
- Dust Mite Covers: Encase your mattresses, pillows, and box springs with dust mite proof covers. For your mattress and pillow preferably use dust mite covers made from a woven fabric with pore sizes so tiny that mites and their droppings cannot pass through. These covers tend to be breathable and can be washed. For your box springs, cheaper, low-maintenance vinyl covers are a good choice. For more information on covers please also read the article Which Dust Mite Covers Are Right for Your Bed.
- Wash sheets and blankets every week in hot water with temperatures of > 55°C (130°F).2 Many front loading washers (European style) have an internal heating element and can easily heat water up to the required temperature. The recommended temperature setting is 60°C (140°F). Some white cotton sheets and covers can even tolerate 95°C (203°F). Please check the label and manufacturer’s specifications to ensure the fabric can tolerate the temperature you set.
- Typical American top loaders do not always achieve the 130°F or higher necessary to kill dust mites. If you are allergic to dust mites, a washer with an integrated heater might however be worth the investment. As an alternative, washing your bedding in warm water with detergent and bleach can also significantly reduce the number of mites and their allergen.3
- Reduce the relative humidity in your bed room (and if possible the whole house) to ideally less than 50%.4 Since the required humidity for dust mites is dependent on the temperature, reducing the humidity to below 60% can already be effective in warmer climates. Get a digital hygrometer/thermometer combination to make yourself familiar with the humidity and temperature conditions in your bedroom.
- To effectively control the humidity and temperature, you probably will have to use air conditioning and possibly a dehumidifier.
- Also consider removing carpets from your bedroom. Opt for a wooden or tiled floor instead. Carpets directly laid on concrete lead to condensation and thus high levels of mites and even mold. For this reason, they should be removed in any case.
- If your child is allergic to dust mites, limit the number of plush toys in the bedroom. You can put plush toys in the freezer (for about 16 hours at -15°C) which kills dust mites. However, this doesn’t remove them or their allergen, so after freezing you need to wash them to remove the dead mites and the allergen.5
How to vacuum carpets in your house without spreading dust mite allergens: Some vacuum cleaners allow dust mite allergens to pass through the dust bag. To prevent this, get a vacuum cleaner with a HEPA filter. People allergic to dust mites should only be going back to the room 30 minutes after vacuuming to allow for the dust to settle. If you are allergic to dust mites and need to vacuum the carpet yourself, wear an N95 face mask. N95-masks filter out 95% of all particles as small as 0.3 microns.
,Arlian, L, J Neal, M Morgan, D Vyszenskimoher, C Rapp, and A Alexander. “Reducing Relative Humidity Is a Practical Way to Control Dust Mites and Their Allergens in Homes in Temperate Climates.” Journal of Allergy and Clinical Immunology 107, no. 1 (January 2001): 99–104.
 McDonald, Lindy G., and Euan Tovey. “The Role of Water Temperature and Laundry Procedures in Reducing House Dust Mite Populations and Allergen Content of Bedding.” Journal of Allergy and Clinical Immunology 90, no. 4, Part 1 (October 1992): 599–608.
Arlian, Larry G., DiAnn L. Vyszenski-Moher, and Marjorie S. Morgan. “Mite and Mite Allergen Removal During Machine Washing of Laundry.” Journal of Allergy and Clinical Immunology 111, no. 6 (June 2003): 1269–1273.
Chang, Chin-Fu, Francis Fu-Sheng Wu, Chi-Ying Chen, Julian Crane, and Rob Siebers. “Effect of Freezing, Hot Tumble Drying and Washing with Eucalyptus Oil on House Dust Mites in Soft Toys.” Pediatric Allergy and Immunology: Official Publication of the European Society of Pediatric Allergy and Immunology 22, no. 6 (September 2011): 638–641.