The occurrence of pneumoconiosis in blue collar workers with minimal exposure to occupational respiratory hazards was assessed. Personal evaluations included smoking history, occupational history, and posteroanterior chest radiography. A total of 1,422 readable films were analyzed by readers blind to the subjects' ages, smoking history, and occupations. The population makeup was 50.6 percent male, 49.4 percent female, 52.5 percent white, 44.2 percent black, 47.0 percent smokers, and 38.5 percent nonsmokers. Subject ages ranged from 16 to 70 years with a mean age of 33.8 years. Three of the 1,422 radiographs showed evidence of pneumoconiosis having a profusion of small opacities of at least 1/0 according to ILO criteria. All three of the pleural abnormalities were unilateral and uncalcified. Two of the cases were males with a history of prior chest trauma. One case involved a female with no apparent cause for the abnormality. The results were discussed with regard to interpretation of the radiographs, intraobserver variability, and population bias. The authors conclude that there is no evidence for a relationship between smoking and pneumoconiosis in the absence of significant dust exposure, and that using three independent radiograph readings should prevent interpretations of "positive" for pneumoconiosis in workers without significant dust exposure.