An analysis of the incidence and prevalence rates of airway obstructive diseases (AOD) has been conducted in adults in the Tucson community population under study, covering nine surveys, 1972 to 1985 inclusive. It was found that rates of diagnoses increased from initial surveys within each age group, possibly due to the effect of the study per se. The rates increased even more in each age cohort until age 65, demonstrating the effects of aging. Cohort changes in smoking were greater than cross-sectional differences between age groups. The incidence rates of diagnoses with functional impairment are about 7/1000 and are greater in smokers and in males. The new cases of AOD were defined both by functional impairment and/or physician diagnoses. They had lower pulmonary function at the initial examination. This implies a natural history of AOD that starts well before clinical diagnoses. New cases of diseases had a variegated set of associated risk factors. In addition to smoking, there were contributions made by reports of childhood respiratory disease, family history, occupational exposures, alcohol consumption, and IgE (in asthma alone or with other AOD). Use of reported diagnostic endpoints as well as functional impairment contributed more to the understanding of the possible etiology of AOD. Some increases in AOD rates may be a function of more careful study, but cohort rate increases seen in a careful longitudinal study show that a real increase in AOD is likely.