Safety warnings were not issued before tragedy in which 21 runners died in Gansu, China
One word in a weather forecast could mean the difference between life and death.
In May, ultramarathon runners were crossing a stretch of the Yellow River Stone Forest Park in north-west China when the temperature dropped suddenly and they were struck by gale-force winds and freezing rain. The runners were wearing only shorts and T-shirts. They had foil blankets for protection from hypothermia, but these were insufficient and 21 runners died of cold and exposure.