Four decades of rapid economic growth in China has come at a huge price to the environment, from smog-ridden skies to contaminated rivers, toxic soils and “cancer villages”. These increasingly intolerable costs have emerged as a major source of social unrest in recent years. Premier Li Keqiang acknowledged this in his opening address to the National People's Congress (NPC) on 5 March 2015: “China's growing pollution problems are a blight on people's quality of life and a trouble that weighs on their hearts”.