Radiologic screening of 688 inhabitants of the Metsovo area in Northwest Greece revealed that 323 (46.9 percent) had pleural calcifications. The percentage of positive examinations rose with age. Calcifications were observed in all four villages of the area where a material ("luto" soil) had been extensively used for whitewashing until 1940 to 1950. In four other villages in the immediate vicinity, where "luto" had never been used, pleural calcifications were not observed. Results suggest that Metsovo tremolite may have caused pleural calcifications to all individuals born in Metsovo before 1940. This is the first study indicating that environmental asbestos exposure can cause abnormalities in everyone exposed to it.