Secret tunnels and unregistered workers: China's coal mine disaster is a reminder of darker days

In Shanxi, the province that sits at the heart of China's coal-mining industry, there's long been a saying: "Only go down a coal pit when you have no other way out." For decades, life in these pits was intertwined with tragedy. It became so common that it gave rise to other sayings: about how miners were "exchanging their lives for money" or "staking their lives for tomorrow" when they ventured into underground tunnels where they died from gas explosions, flooding and shaft collapses.