Complicated coal workers' pneumoconiosis (CWP) is defined by the presence of lung lesions measuring greater than 1 cm in diameter on the chest x-ray. Fewer than 5% of miners with simple CWP develop this complication, also called progressive massive fibrosis (PMF). Symptoms of PMF include productive cough and dyspnea. The prognosis of PMF is poor. [LaDou, p. 381; Harber, p. 365-6] "From the mid-1970s through the late 1990s, the prevalence of CWP among long-tenured coal miners decreased from more than 30% to 5%, and the most severe form of CWP, called progressive massive fibrosis, was nearly eradicated." [PMID 31820465
] See "Coal workers' pneumoconiosis."