" About sixty percent of Shin’s class was assigned to the coal mines, where accidental death from cave-ins, explosions, and gas poisonings was common. Many miners developed black lung disease after ten to fifteen years of working underground. Most miners died in their forties, if not before. As Shin understood it, an assignment in the mines was a death sentence. "

― Blaine Harden , Escape from Camp 14: One Man's Remarkable Odyssey from North Korea to Freedom in the West