General Medical Information

Environmental Control

Richard L. Mabry

Animal dander should be completely avoided. However, patients with allergies often are too attached to their pets to give them up. At least six antigens from saliva, cat hair, dander, and pelt have been incriminated in cat allergies. Most of these are contained in cat dander. These small, light particles linger in a carpet for 3 to 6 months or more after the cat is gone, and they often are carried on clothing, to be found eventually in public places where no cat is known to have been. If animals to which a patient is sensitive cannot be avoided, they should at least be kept out of the patient’s primary living and sleeping areas. Reservoirs such as rugs and upholstered furniture should be cleaned frequently with a high-efficiency particle-arresting (HEPA) filter vacuum.

Dust is ubiquitous. “House dust” as a unique antigen does not exist. It contains antigens such as animal dander, mold, cockroach, and house dust mite. The major species of house dust mite are Dermatophagoides farinae and Dermatophagoides pteronyssinus. Dermatophagoides microcerus and Euroglypha spp. are a minority with uncertain clinical significance. The antigen of the dust mite is contained in its dung balls. Dust mites thrive in moist areas, feeding off the scales from human skin. Application of benzyl benzoate to carpets and upholstered surfaces followed by vacuum removal effectively kills mites for variable periods. Tannic acid denatures mite antigen but does not kill dust mites. No substance currently available performs both functions. Antigens from cockroach bodies are clinically important. Thorough environmental control is needed to minimize exposure of a sensitive patient.

Molds are both outdoor and indoor sources of antigen. Outdoor molds are common from spring until the first hard freeze. They are especially prevalent in compost bins, leaf piles, flower beds and gardens, and grass clippings. Indoor molds are present all year, especially in damp, warm environments. Mold often is found in old shoes, luggage, books, old newspapers, plants, wallpaper and carpet, especially if previously wet, refrigerator drip pans, shower curtains, and bathroom tile. Houseplants are an important source of mold, as are dried flowers, and both should be kept out of bedrooms and major living areas.

Pollen avoidance is almost impossible short of giving up all outside activities. However, pollen masks help patients during mowing and gardening, and appropriate filtration systems in heating and air-conditioning systems produce a pollen-free indoor environment to which the patient can retreat. Besides learning to avoid specific inciting antigens, a patient with allergic rhinosinusitis should be instructed in measures that minimize nonspecific irritation of the nasal mucosa. A saline nasal spray should be used to cleanse the nasal passages. Avoidance of tobacco smoke and irritating fumes should be emphasized. Proper ambient humidity should be maintained; wintertime nasal dryness is detrimental to nasal function, whereas humidity higher than 50% allows mold and house dust mite to flourish.