<%-- Page Title--%> Health <%-- End Page Title--%>

<%-- Volume Number --%> Vol 1 Num 147 <%-- End Volume Number --%>

March 26, 2004

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House Dust Allergy

House dust allergy is common even in clean homes. It is a major cause of year-round runny or stuffy nose, itchy, watery eyes and sneezing for allergy sufferers. Dust can also make people with asthma experience wheezing, coughing and shortness of breath.

<>Why does house dust cause allergic reactions?<>
House dust is a mixture of many substances. Its content varies from home to home, depending on the type of furniture, building materials, presence of pets, moisture and other factors. A speck of dust may contain fabric fibbers, human skin particles, animal dander, microscopic creatures called mites, bacteria, parts of cockroaches, mold spores, food particles and other debris. Of these, animal dander, house dust mites, and cockroaches are the most common culprits. A person may be allergic to one or more of these substances, and, if exposed to the dust, will have an allergic reaction.

Is dust allergy a sign of a dirty house?
No. A dirty house can make a house dust allergy problem worse, however. Normal housekeeping procedures may not be enough to get rid of house dust allergy symptoms. This is because many of the substances in dust cannot be removed by normal cleaning procedures. For example, no matter how vigorously you dust or vacuum, you will not reduce the number of dust mites present deep within carpeting, pillows, and mattresses. Vigorous cleaning methods can put more dust into the air making symptoms worse.

What are dust mites?
Tiny microscopic creatures called dust mites are an important cause of allergic reactions to house dust. They belong to the family of eight-legged creatures called Arachnids. This family also includes spiders, chiggers and ticks. Dust mites are creatures that live well and multiply easily in warm, humid places. They prefer temperatures at or above 70°F with a relative humidity of 75-80 percent and die when the humidity falls below 40-50 percent. They are rarely found in dry climates.

People who are allergic to dust mites react to proteins in the bodies and faeces of the mites. These faecal particles are found in the highest concentrations 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 once the disturbance is over. Dust mite-allergic people who inhale these particles frequently experience allergy symptoms. In fact, a dust mite allergic patient who sleeps for 8 hours every night spends one third of his life with his nose in direct contact with a pillow loaded with dust mite particles!

There may be many as 19,000 dust mites in one gram of dust, but usually between 100 to 500 mites live in each gram. (A gram is about the weight of a paper clip.) Each mite produces about 10-20 waste particles per day and lives for 30 days. Egg-laying females can add 25-30 new mites to the population during their lifetime.

Mites eat particles of skin and dander, so they thrive in places where there are people. Dust mites don't bite, cannot spread diseases and usually do not live on people. They are harmful only to people who become allergic to them. While usual household insecticides have no effect on dust mites, there are ways to reduce exposure to dust mites in the home.

Why is mold present in house dust?
Mold is commonly found in outdoor air. However, 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. Mold require two factors to grow indoors: (1) free moisture that can occur in the form of relative humidity above 50 percent, leakage from pipes or foundations, or any ongoing source of water, and (2) something to grow on. Molds particularly like to grow on wallboard, wood, or fabrics, but will grow virtually any place if they are given a chance.

Mold spread by producing spores that can become airborne. These spores end up in house dust where they grow. Dust from mold-contaminated houses can cause allergy symptoms if a mold-sensitive person inhales it.

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