SY 1581 was hard at work dragging a train of ore empties from the smelter complex at Baiyin to the copper mine at Shenbutong, around 17 km to the north, on 26 November 2005. The train wasn't the only thing heading north that morning. A cloud of pollution swept up the valley as well, severely affecting the visibility. In the five days we were in the area, this was the only occasion the ore empties ran at a suitable time.