Miners get coal workers’ pneumoconiosis, known as black lung, by breathing tiny dust particles generated when powerful machines cut through coal and rock. Over time, dust collects in miners’ lungs and causes breathing difficulties. In the early stages, miners may not notice any symptoms. As the disease progresses, the lungs become scarred, shriveled and black, and miners often develop a cough or shortness of breath. In the late stages of the most severe form of the disease, known as progressive massive fibrosis, miners have to struggle for each breath. Read more at NPR.