The questions studied included whether the above named risk factors reduced the maximally attained level of pulmonary function in early adulthood, foreshortened the postulated stability of level of pulmonary function between age 18 and 35 and/or unfavorably affected subsequent decline in level of pulmonary function. FEV1/h2, VC/h2 and FEV1/IVC were studied, using graphic smooth techniques and regression analyses techniques on both cross-sectional and longitudinal datasets. In addition, the investigators tested the hypothesis stating that early adult symptoms of asthma, increased bronchial responsiveness, markers of allergy influenced who became a smoker, influenced the amount smoked and/or influenced who stopped smoking relatively early in adult life, using logistic regression analyses and survival analyses.