Black lung disease is the popular name for CWP (Coal Worker Pneumoconiosis).
It is cause after a long-lasting exposure to coal dust, normally ocurring in a couple of months or even years, depending on the intensity of the exposure. It is noticed mosty by strong coughs and by literally having black lungs.
The image pasted below will give you a better idea of how CWP looks like.
Hope it helped,
Happy homework/ study/ exam!