Environmental control measures help eliminate triggers that initiate the allergic reaction and reduce the conditions that sustain it. The most frequent offenders are the ubiquitous dust mites, which are ideally suited to living in the home environment. Control measures consist of minimizing their reservoirs in the patient's bedding, carpets, and upholstered furniture; decreasing humidity; and using acaricides. Cats are the source of another important indoor allergen that becomes and stays airborne as small particles. Removal of the animal (or washing it weekly) and the use of high-efficiency particulate air filters for air ducts and vacuum cleaners are useful in reducing dust mite and cat allergens. Dogs and rodents also produce allergens offensive to the sensitized patient and should be removed or relegated outdoors. Cockroaches have become an increasingly prevalent source of allergens responsible for asthma and rhinitis. Their removal is the focus of research, because current control measures are usually inadequate. Molds, which thrive in any moist environment, produce allergens. Closed windows prevent further influx of outdoor molds and pollens, whereas those harbored indoors, including those residing on plants, should be eliminated.
