The miners take turns chopping the coalface. All around us a jury-rigged jumble of tree trunks is wedged against the tunnel’s ceiling, our only protection from being crushed by the five hundred meters of rock between here and the floor of the northern Afghan desert. My claustrophobia mounts with every chunk of coal that dings off my plastic helmet. One miner crouches in the access shaft and shovels coal into an iron railcar. My headlamp catches his face, and I see his teeth are flecked with black.