Changing concepts of allergic disease: the attempt to keep up with real changes in lifestyles

In the past 100 years, changes have occurred in the outdoor environment and in houses that have contributed to the increased prevalence of hay fever and asthma. Much evidence indicates that exposure to indoor allergens is an important cause of asthma. Changes in housing that have contributed to the increased prevalence and severity of asthma include increased temperature, decreased ventilation, and permanent carpeting. In addition to these changes, geographic differences in allergens, deficiencies in cleanliness, poor health care, passive smoke, and lack of exercise also contribute to the increase in severity of asthma that has occurred. The management of asthma includes controlling exposure to indoor allergens and seeking additional treatable causes of asthma (e.g., fungal allergens). Changes will continue to occur, and physicians who treat allergic diseases should become involved in the design of houses to limit exposure. Many questions regarding allergen measurement and control remain.