Specific changes that have occurred in the housing industry over the last 25 years have contributed to making the home environment a better place for indoor allergens to thrive. These changes include higher indoor temperatures, increased humidity, greater use of wall-to-wall carpeting, “tighter” (more energy-efficient) houses, and the use of cool-water detergents. Unfortunately, since 65 to 95 percent of children and young adults with asthma are allergic to indoor allergens, the indoor environment has become more hazardous. Although commonly ignored, environmental control is one of the most successful and cost-effective means of alleviating allergy symptoms. It can reduce the need for medications, cut the number of doctor and hospital visits, and save time lost from work and school.
Although the level of indoor allergen exposure does not necessarily correlate with the severity of symptoms, there are threshold levels of allergen exposure that are likely to sensitize the individual who is at risk. The route of exposure does not seem to make a difference, regardless of whether the individual has asthma, allergic rhinitis, or atopic dermatitis. All of the major indoor allergens are capable of contributing to each of these diseases. Lowering the level of specific allergens can be helpful in either treating a patient with clinical symptoms or decreasing the chances of an individual developing allergic disease.
The major indoor allergen is now recognized to be the dust mite, which is a microscopic (0.3 mm), eight-legged, sightless relative of the spider. The mite’s fecal pellet is an important reservoir for the mite’s allergen and the major form on which the allergen becomes airborne. Because of its relatively large size, the mite allergen becomes airborne only during or shortly after a disturbance (vacuuming, walking on carpet, jumping on beds, etc.). Little or no allergen is detected in the undisturbed condition, and the presence of airborne allergen falls rapidly after disturbance. Unfortunately, patients often sleep or sit with their heads very close to reservoirs of mite allergen, such as pillows, blankets, mattresses, and upholstered furniture. Efforts to eliminate dust mites from the bedroom, where we spend one-third of our lives, are critically important. Alive and well inside the warm, humid conditions of pillows, dust mites feed on the skin scales people shed while sleeping. Allergen-barrier pillow covers can help protect the allergy victim from dust mites and other allergens. Other control measures are discussed below.
Animals, especially cats and dogs, are another major source of indoor allergens. The major cat allergen, Fel d 1, appears to be produced primarily from the skin and not from the hair or saliva. It is clear that allergic individuals are at risk of developing IgE antibodies to the major dog allergen as well detoxic vaistinese. Furthermore, high levels of both cat and dog allergen can be found in houses without animals and in the dust from schools. Most likely, the allergen is carried into these areas on clothing.
Unlike mite allergen, cat allergen (and probably dog allergen) is small enough and light enough to remain airborne for long periods of time. Although air currents can keep cat allergen from settling, increased ventilation and an air filtration system can effectively decrease the level of cat allergen in a house.
Other potential indoor allergens include cockroaches, rodent protein derived from urine, and mold spores. Cockroach allergen does not stay airborne for prolonged periods and in most cases is not a “bedroom” allergen. Rodent allergen problems are mostly related to the dry allergen in the litter. The major indoor molds are Aspergillus and Penicillium (mildew), although elevated levels of other molds (Alternaria, for example) may occur in specific situations. The level of mold spores in a particular house would be dependent on a variety of factors, including the age of the house, the type of heating system and insulation, and the degree of dampness in such areas as basements, bathrooms, and kitchens. Mold growth generally requires a level of humidity higher than that required for growth of dust mites detoxic precio.
It is well established today that exposure to indoor allergens can increase bronchial hyperreactivity and induce symptoms in patients with asthma. By effectively decreasing exposure to indoor allergens, one may be able to decrease the hyperreactivity.
Environmental control measures can be divided into those involving the bedroom and those involving the rest of the house. In the bedroom, it is necessary to cover the mattress and box spring with impermeable covers. The linens should be washed every one to two weeks at temperatures of at least 130ºF. Ideally, the floors should be wooden or linoleum. Wall-to-wall carpeting can harbor billions of dust mites, serving as a continuous reservoir of allergen. Although carpeting and upholstered furniture can be treated with a variety of chemical agents to kill mites (pyrethroids and benzyl benzoate) or denature them (tannic acid 3%), repeated treatments are necessary as none of the methods are more than 90 percent effective. Carpeting on cement floors, as is often the case in the basement and the first floor of houses built on a slab, is a special problem because of the elevated moisture in the carpeting. Even when the ambient water vapor is low, the carpeting often retains moisture, enhancing growth of mold and dust mites. If one is lucky enough to be making recommendations, wood, tile, or linoleum floors, especially in the bedrooms, and furniture of wood, leather, or vinyl are preferable to fitted carpets and upholstered furniture.
While total absence of animals in the house is the best way to limit exposure to animal allergen, this decision may not always be practical. Even when a cat or dog is removed from a home, it may take up to 20 weeks for allergen levels to return to levels normally present in houses without these animals. While keeping an animal outside is better than keeping it inside, allergen will enter the home on clothing. Using noncarpeted floors, a good air filtration system, and a vacuum cleaner with a HEPA filter may decrease levels of animal allergens enough to prevent symptoms. Washing a cat or dog thoroughly can reduce airborne allergen by as much as 85 percent. Unfortunately, the washing needs to be done every one to two weeks.
Treatment of indoor allergens such as rodents, cockroaches, and molds is based mainly on common sense. Rodent allergen is found in the urine, so careful handling of litter is necessary if the rodent is not removed completely detoxic cena. Obviously, pets such as guinea pigs and hamsters should never be in the bedroom. Eliminating cockroach allergen involves eliminating cockroaches. Sealing food, regularly cleaning the kitchen, and using bait all play a role in eliminating the problem. Mold elimination involves avoiding water reservoirs, such as flooded areas or damp carpeting.
Finally, during certain seasons it becomes important to control indoor relative humidity and to keep outdoor allergens such as pollens from getting indoors. Ideally, the relative humidity inside the house should be kept at 50 percent or below in order to decrease propagation of dust mites. Keeping windows closed, especially at night and early in the morning; drying linens indoors; avoiding whole-house fans, which pull in outside air; and using air conditioners and dehumidifiers all help maintain a better indoor environment.
While a variety of different medications have become available to help control allergic symptoms, it makes sense to first try to control allergens in the home. If environmental control is successfully accomplished, symptoms may be prevented or at least controlled with lower doses of medication.