In a genetic-epidemiologic study of chronic obstructive pulmonary disease (COPD) observations adjusted for age, sex, race, and smoking indicate certain factors to be associated with increased pulmonary function aberrancy, and suggest that they are risk factors for COPD. These presumptive "risk factors" include not only cigarette smoking, but also alpha1-antitrypsin (Pi system) variation, one or more other familial components, low socioeconomic status (SES), and, in whites, ABO blood type (either absence of "B" or presence of "A").