INDOOR ALLERGY SURVIVAL TIPS
As many as 10 percent of the general population and (in some regions) 90 percent of people with allergic asthma are sensitive to dust mites. Recent studies in the United States suggest that at least 45 percent of young people with asthma are allergic to dust mites.
Dust mite particles are just the right size to be inhaled. They 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. A dust mite allergic patient who sleeps for eight 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.) Egg-laying females can add 25 to 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, and cannot spread diseases. They are harmful only to people who become allergic to them. While usual household insecticides have no effect on dust mites, there are ways that allergic people can reduce exposure to dust mites in the home.
Why is mold present in house dust?
Molds are commonly found in outdoor air, and they come in any time you open a door or window. 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: (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.
Molds 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.
Does house dust contain cockroaches?
As unappealing as it seems, cockroach particles can be a component of house dust. This is most common in older, multifamily housing and in the southern United States where complete extermination of cockroaches is very difficult. Allergic individuals, particularly those with asthma, will tend to have increased symptoms when they go into such houses. Cockroaches require food and moisture to survive, so eliminating sources of each can help reduce exposure. In cockroach endemic areas, the services of a skilled professional exterminator will be required to keep cockroaches under control.
Is house dust allergy seasonal?
Yes. In the United States, dust mite populations tend to peak in July and August, and their allergen levels stay high through December. Mite allergen levels are lowest in late spring. Some dust mite-sensitive people report that their symptoms get worse during the winter. That's because mite fecal particles and pieces of dead mites, both of which trigger dust mite allergy, are still present. Mold levels tend to peak during the summer months depending on where you live since some tropical areas have molds year-round. There is also evidence that cockroaches have a seasonal pattern, peaking in the late summer.
Forced-air heating systems tend to blow dust particles into the air. As they dry out over time, even more of the particles become airborne. This does not account for the seasonal pattern, however, since air blows through the same ducts during the summer when air conditioning is used. People may have fewer symptoms from house-dust exposure during the summer because they spend more time outdoors.