Return to Previous Page

House Dust

What’s in it. And what you can do about it.

Allergy image

House dust is a mixture of many substances. Its content may vary from home to home, but the most common allergy triggers contained in house dust are dust mites, cockroaches, fungi (mold), and animal dander. Exposure to even small amounts of the offending allergen can cause allergy symptoms. House dust exposure can also trigger asthma symptoms, such as wheezing, coughing, chest tightness, and shortness of breath.

Dust Mite Allergy
Dust mites are the most common cause of allergy from house dust. Dust mites are hardy creatures that live and multiply easily in warm, humid places.

High levels of exposure to dust mites are an important factor in the development of asthma in children. People who are allergic to dust mites react to proteins within the bodies and feces of the mites. These particles are found mostly in pillows, mattresses, carpeting, and upholstered furniture. They float into the air when anyone vacuums, walks on a carpet, or disturbs bedding, but settle out of the air soon after the disturbance is over. Dust mite-allergic people who inhale these particles frequently experience allergy symptoms.

Cockroach Allergy
Many houses have dust that contains parts of cockroaches. This is most common in older, multifamily housing and in the southern United States, where complete extermination of cockroaches is very difficult. Individuals allergic to cockroach protein, particularly those with asthma, tend to have increased symptoms if they live in such houses.

Dust mites are the most common cause of allergy from house dust.

You do not have to actually see cockroaches to have a problem. The allergen is derived from saliva, fecal material, secretions, skin casts, and body parts. It is usually at the highest levels in kitchens, but may be found throughout the home. The levels in bedrooms may be most associated with allergic disease. Cockroaches require food and moisture to survive, so eliminating sources of each can help reduce exposure.

Indoor Mold Allergy
Molds found indoors come from the outdoors. Any house can develop a mold problem given the right conditions. You might not see it growing on the walls, but it may still be present in your home. Molds require two factors to grow indoors: free moisture from condensation, leakage from pipes or foundations, or any ongoing source of water; and something to grow on that provides them a food source.

Molds spread by producing spores that can become airborne when they are disturbed directly or by air currents. These spores end up on surfaces where they grow. Dust from mold-contaminated houses can cause allergy symptoms if a person who is allergic to the mold inhales them.

Animal Allergies
Cats and dogs are the most common cause of animal allergy, but any warm-blooded animals can trigger allergy symptoms. It’s not just the hair or skin particles that contain the allergens, but also the urine and saliva. Mice can also trigger allergies if present in sufficient numbers. Allergens from domestic animals, especially cats, may be carried on the clothing of pet owners outside the home into the workplace and schools. In fact, cat allergen is one of the most common allergens found in the dust in schools.

Relieving House Dust Allergy Symptoms
Once your doctor has identified your allergy triggers, steps should be taken to avoid them. Research has confirmed that targeted avoidance can be as effective as medications in reducing symptoms. The usual case requires targeted avoidance, medications prescribed by your doctor, and in many cases, specific allergen immunotherapy (allergy shots) to bring the problems under control.

The following are tips for reducing house dust allergens:

  • Measure the indoor humidity and keep it below 55 percent. Do not use vaporizers or humidifiers. You may, however, need a dehumidifier. Use vent fans in bathrooms and when cooking to remove moisture. Repair all water leaks.
  • Remove wall-to-wall carpets from the bedroom if possible. Use a central vacuum or a vacuum with a HEPA filter regularly. If you are allergic, wear a N95 filter mask while dusting, sweeping, or vacuuming. And remember, it takes over two hours for the dust to settle back down, so if possible, clean when the allergic person is away, and don’t clean the bedroom at night.
  • If you must keep your pet, keep it out of the bedroom at all times. However, it is best to remove the animal from the home.
  • Encase mattresses and pillows with “mite-proof” covers. Wash all bed linens regularly using hot water.
  • Do not leave out uncovered food at night. Dispose of food wastes (including fast food wraps) in a tightly sealed garbage can. Use roach traps. Schedule regular professional pest control.

Source: American College of Allergy, Asthma & Immunology,

This article was originally published in Coping® with Allergies & Asthma magazine, Spring/Summer 2010.