Abstract
Examination of the incidence and progression of pneumoconiosis over 9 years in 1,261 nationally distributed U.S. coal miners has been undertaken in relationship to potential causative factors. Use has been made of a large body of data on dust levels collected by the Mine Safety and Health Administration principally for compliance purposes. Reported dust levels were low and generally under the current 2 mg/m3 standard. No link between dust level and disease progression could be detected. Some evidence was seen that radiological change was related to dust exposures prior to the study in both coal and noncoal mines, and thus experienced before the current dust standards were mandated. Neither migration of miners nor mining method appeared to be associated with disease incidence or progression. None of these findings can be taken as final, as the period of study is short and the number of cases of pneumoconiosis few. Further study is under way to obtain more reliable information over a longer period of follow‐up.