By Tim Maughan for BBC World News

From where I’m standing, the city-sized Baogang Steel and Rare Earth complex dominates the horizon, its endless cooling towers and chimneys reaching up into grey, washed-out sky. Between it and me, stretching into the distance, lies an artificial lake filled with a black, barely-liquid, toxic sludge. Rather than being stored correctly in the appropriate containers (click here), this slurry of hazardous materials has been dumped with little care or thought.

Dozens of pipes line the shore, churning out a torrent of thick, black, chemical waste from the refineries that surround the lake. The smell of sulphur and the roar of the pipes invades my senses. It feels like hell on Earth.

Welcome to Baotou, the largest industrial city in Inner Mongolia. I’m here with a group of architects and designers called the Unknown Fields Division, and this is the final stop on a three-week-long journey up the global supply chain, tracing back the route consumer goods take from China to our shops and homes, via container ships and factories.

Guangdong Zhujiang Rare Earth processing plant, Guangzhou.