A group of lawyers has filed a lawsuit against the Chinese government for failing to prevent the severe smog that has covered the north over the past week, underlining the discontent voiced by tens of millions of citizens online. Beijing and many other cities in north China are entering their sixth day running of pollution “red alerts”, which have closed down schools, roads and factories. More than 350 flights were grounded in Beijing on Tuesday due to poor visibility. “Progress on air pollution has been lots of talk and hardly any action for the past few years,” wrote Cheng Hai, a Beijing-based lawyer, in the preface to the lawsuit. He is one of five lawyers bringing a case against the local governments of Beijing, Tianjin and Heibei — three major regions in the smog-afflicted north — for failing to implement their own environmental laws. “This is the first time that lawyers have used an administrative lawsuit to protest the government’s treatment of air pollution,” said Wu Qiang, a former lecturer in politics at Beijing’s Tsinghua University who writes on political protests. “It marks a new stage in the environmental movement.