CHARLESTON, W.Va. (AP) — A half-century ago, the nation's top health experts urged the federal agency in charge of mine safety to adopt strict rules protecting miners from poisonous rock dust. The inaction since — fueled by denials and lobbying from coal and other industries — has contributed to the premature deaths of thousands of miners from pneumoconiosis, more commonly known as “black lung." The problem has only grown in recent years as miners dig through more layers of rock to get to less accessible coal, generating deadly silica dust in the process.