Dust Allergies

By Pierre P. Gagnon, MD

Pierre-Paul Gagnon, MD

More Allergy, Asthma & Infectious Disease Articles

Dust Allergies

Substances that cause allergic reactions are called allergens. An allergic reaction is the body's response to a substance that many people can tolerate without difficulty. People have varying degrees of sensitivity to an allergen. Allergy sufferers who are highly sensitive will have symptoms every time they are exposed to an allergen. People who are only slightly allergic require a higher concentration of allergens to trigger symptoms.

The allergen load is the total exposure, at one time, to the allergens to which you are sensitive. Small amounts of a variety of allergens can overload your threshold as can a large amount of a single allergen. It is the total accumulation of allergen exposure which will determine if your tolerance is exceeded.

The Goal Of Allergen Avoidance

You do not need to totally eliminate exposure to allergens all of the time. In order to obtain relief, you only need to prevent overflow. It is important to know the particular allergens to which you are sensitive. You can then concentrate on those steps which are most practical and those which are most effective at reducing your exposure. Allergies are not an all-or-nothing phenomenon. Approach your allergen avoidance program by setting priorities and making informed choices, which will prevent overflow.

The House Dust Mite

Although there are many components in house dust to which people may be allergic, the most important is the dust mite. Dust mites are eight-legged arachnids, relatives of the spider. The dust mite is microscopic and therefore cannot be seen by the human eye. An adult mite is approximately 300 microns (3/10 mm) in length, having developed over approximately 25 days through egg, larval and nymph stages. Adults live for two to three months, during which time the female mite can lay 25 to 50 eggs every three weeks.

Where Dust Mites Live

Dust mites are present in nearly all homes in areas where the relative humidity is greater than 50% for some portion of the year. The photophobic mites thrive in a dark, warm and humid environment found in pillows, mattresses, box springs, blankets, carpets, and upholstered furniture. Literally millions of mites can inhabit a single bed, as it provides both a perfect condition for growth and their greatest food source the shed scales from human skin.

What Can Be Done?

It is easy to see why the bedroom provides the greatest source of dust mite allergen in the home. Emphasis is therefore placed on decreasing allergen exposure in the bedroom as it is the room where individuals spend a large percent of their time each day and where they are most likely to come in close proximity to the offending allergens.

Scientific studies have shown that taking steps to minimize dust mite allergen exposure in the bedroom leads to a decrease in allergic symptoms and a decrease in medication requirements for the dust-allergic patient. Studies have also demonstrated the effectiveness of encasing the mattress, pillows, and box spring in zippered, allergen-impermeable covers. Encasing this bedding in allergen-impermeable covers is therefore considered one of the primary steps in reducing dust mite exposure. Other bedding, which cannot be encased, should be washed in hot water every two weeks.