effective in controlling mite allergens (Burr et al., 1980; Korsgaard, 1982). In addition, several general medical tests have suggested that avoidance measures should be considered in patients who have a certain typical history. As discussed earlier, however, many allergic patients are not aware of an association between dust exposure and their symptoms (particularly the association between dust and asthma or atopic dermatitis). Today, there is considerable evidence that full avoidance (i.e., 95 percent reduction of mite allergen) can be achieved and can reduce both symptoms and bronchial reactivity. For example, moving patients to a hospital room or sanatorium has been consistently effective (Dorward et al., 1988; Ehnert et al., 1991; Platts-Mills et al., 1982; Warner and Boner, 1988); these units generally have very low levels of mites (i.e., less than 20 mites/g of dust) and mite allergen (less than 0.4 µg of Der p I/g). Recently, four controlled studies of the effects of avoidance measures conducted in the homes of patients have found significant improvement in both asthma symptoms and bronchial hyperreactivity (Dorward et al., 1988; Ehnert et al., 1991; Murray and Ferguson, 1983; Walshaw and Evans, 1986).

Avoidance measures can be divided into those for use in the bedroom and those for use in the rest of the house (Box 3-1). In the bedroom, the following have been shown to be effective: covering mattresses and pillows with impermeable covers; washing bedding at 130°F once per week

BOX 3-1 Avoidance Measures for Mite Allergen

A. Bedrooms

▪ Cover mattresses and pillows with impermeable covers

▪ Wash bedding regularly at 130° F

▪ Remove carpets, stuffed animals, and clutter from bedrooms

▪ Vacuum clean weekly (wearing a mask)*

B. Rest of the House

▪ Minimize carpet and upholstered furniture; do not use either in basements

▪ Reduce humidity below 45 percent relative humidity or 6 g/kg

▪ Treat carpets with benzyl benzoate or tannic acid

* There is a temporary increase in potential exposure to allergens associated with the vacuuming process. The net potential for exposure should be reduced by vacuuming, however, and is considerably less than the cumulative effects of not vacuuming. Wearing a mask while vacuuming should help reduce exposure while vacuuming.



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