Over 40 years ago, almost half of all miners who worked over 25 years old contracted black lung, a harrowing disease that constricts air flow, making it hard for victims to eat and breathe and eventually taking their life.
But in 1969, Congress made a promise: Mining companies would have to keep dust levels down, and black lung would be virtually eradicated.
Forty years later, black lung has come back with a vengeance. And its victims are younger and the cases more dire, despite having worked fewer years in the coal mines.