The study was renewed in 1992 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. Data were available in two populations: the Childhood Respiratory Disease Study in East Boston (CRD) and the Normative Aging Study Population (NAS). This group has shown that increased airway responsiveness was associated with altered patterns of lung growth (in children) and reduced levels of lung function (in adults). They also have shown that airway responsiveness was cross-sectionally associated with chronic respiratory symptoms in both children and adults. However, asymptomatic airway responsiveness was extremely common, occurring in 20 percent to 60 percent of responsive subjects, depending on how responsiveness and chronic symptoms were defined. Asymptomatic bronchial responsiveness was thought to represent subclinical or mild airway inflammation. Alternatively, it may have represented differences in mechanical factors leading to airway narrowing.