From 1981 to 1991, to characterize the role of allergy and airways responsiveness in modifying growth of lung function in children and young adults in a community-based random population, the Childhood Respiratory Study in East Boston. From 1992 to 1997, to examine the relationship of respiratory symptoms and illnesses, cigarette smoking, airways responsiveness, and markers of inflammation to growth and decline in lung function in two well-characterized and investigated community-based populations of children and adults, the Childhood Respiratory Study in East Boston and the Normative Aging Study.