October 17, 2014

What is a house dust allergy?

House dust allergy is sensitivity to a mixture of substances including waste particles from dust mites. Other component substances can include mold spores, insect debris including cockroaches, bacterial toxins and animal dander.

What are dust mites?

Dust mites are microscopic creatures that live off tiny flakes of human skin that people shed each day. They require nests to live in, a source of food and sufficient humidity (generally >50%). The major reservoirs of dust mites include mattresses, pillows, bed linens, carpets, stuffed animals and upholstered furniture. Effective avoidance measures may include reducing areas that can harbor nests in the house (e.g. carpet, furniture and drapes) and controlling humidity. Dust mite allergy is sensitivity to waste particles and fragments of the mite that become airborne and are inhaled. Because these fragments are relatively large, they do not stay airborne very long after their source is disturbed. Thus, air filtration plays very little role in controlling exposure to dust mites.

How can I help control dust mite allergies?

A “dust-free” environment is obviously an unreachable goal. However, there is substantial evidence that rigorous house dust control can reduce allergen exposure symptoms and need for medicines if enforced over a long period of time. We emphasize particular attention to the bedroom to provide an “oasis” from allergens and irritants during several hours of the day spent there.

It is our experience that patients and families who carry out the suggested measures can achieve benefits, manifested by better symptom control and reduced requirement for maintenance and rescue medicine. However, these benefits are seen only with much sustained commitment to allergen control.

In the bedroom:

  1. Cover pillows and mattresses with zippered covers which are impermeable to mite and mite allergen. We will give you direction on where these might be obtained.
  2. Wash sheets, pillow cases and blankets at 130 degrees Fahrenheit weekly. The blankets should be replaced with those that can be washed.
  3. Comforters should be removed, covered or washed. Remove clutter, soft toys and upholstered furniture.
  4. Where possible, carpet should be removed or replaced with area rugs that can be cleaned/washed.
  1. Use wipeable furniture that can be easily cleaned with a damp cloth on a regular basis.

In the home & air control:

  1. When vacuuming or cleaning, the allergic patient should wear a dust mask. The allergic patient should not be in the room for 1-2 hours after cleaning as disturbed dust needs time to settle out of the air. Consider vacuuming using a cleaner with a filtration system (Hepa-type vacuum).
  2. Reduce upholstered furniture, particularly old sofas.
  3. Ideally, one should replace carpet with polished flooring where possible. Carpets on concrete slabs or over-poorly ventilated crawl spaces should be replaced with polished flooring if possible.
  4. Control humidity to less that 50% relative humidity at normal temperatures, i.e. 68-72 degrees.
  1. Room humidifiers can be a source of mold and mite growth. Air conditioning can prevent the high heat and humidity which stimulate mite growth.

Air systems for dust mites are not thought to be effective as the particles are airborne for fairly short periods of time and are not “filterable”. There is little evidence that cleaning of duct work in home or expensive air filtration systems on central heating and air conditioning systems are of clinical benefit.

There have been chemicals tested that kill or denature mite allergens. Most investigators who have tested chemical treatment of carpets believe that the killing of mites is not possible with currently available chemicals. There may be new products in the future that are more effective.

Patients who are allergic to mites or molds may have some increased exposure and symptoms if living in basements or overly damp housing. Moving from a basement to an upstairs room may be of benefit. Consider use of portable dehumidifiers in the bedroom if these changes are not possible.