We have performed cross-sectional surveys on the prevalence of symptoms of obstructive lung disease and on lung function in about 7000 residents aged 7 years and older of one urban and two rural communities, in Connecticut and in South Carolina. The results provide data on normal lung function in relation to age, sex, race and smoking habits, as well as comparison of symptom prevalence and of lung function in urban vs. rural residents and in black vs. white children and adults. We plan to use this extensive data base in longitudinal studies of lung function increase and incidence of asthma and of respiratory symptoms in children and adolescents, and of lung function decrements with age in adults, as a function of smoking habits, residence and occupation. There is emphasis on the study of women, adolescents and blacks, about whom few such data are available. The results will be related to data on outdoor and indoor air pollution, to evaluate the significance of these as risk factors in obstructive lung disease.