The disease, also called coal workers' pneumoconiosis, is caused by the inhalation of coal dust over a long period. Accumulated coal dust irritates lung tissue and may destroy it. But defense mechanisms in the lungs remove nearly all the dust. Thus, black lung seldom develops in people who have worked in coal mines for less than 10 years.
Physicians diagnose black lung mainly by means of chest X rays.
The disease has two main forms, simple and complicated. The simple form affects only small, scattered areas of the lung and generally has no symptoms. The complicated form damages or destroys a large part of the lung. It results from heavy exposure to coal dust, plus an unknown factor, and causes severe chest pain and shortness of breath. Complicated black lung may worsen even if the victim is no longer exposed to coal dust.