The study was cross-sectional and used a subgroup of the Normative Aging Study, a longitudinal study of aging in men established by the Veterans Administration in 1963. The study used data normally collected during NAS examinations and included smoking history, socio-economic status, anthropometry, respiratory symptoms and illnesses, and pulmonary function. New data were collected on: indices of inflammation as indicated by histamine, leukotriene, and serotonin in urine; autonomic activity as indicated by urinary catecholamine excretion and heart rate variation induced by deep breathing; autonomic responsiveness as measured by pupillary alpha-adrenergic and cholinergic responses.