Hazardous smog - that has for days blanketed north, central and east China - makes plain the scale of the environmental challenge Xi Jinping's incoming government faces. Air quality readings have been pushed off the charts by the foul-smelling, metallic-tasting pall that has cut visibility to a few hundred metres and less. Airports, highways, schools, offices and factories have been closed and thousands of people taken to hospitals. There could be no better way for a new administration to show it means business than by bringing back blue skies and breathable air.

Those should be basic rights for all people, no matter where they live. Unfortunately, cities struggle to attain them, especially those in fast-developing countries like China. Xi's pledge of economic sustainability offers hope. The nation has prospered under a growth-at-all-costs model, but the environment has suffered enormously as a result. Air pollution in Beijing that is the worst in at least a decade has to provide an impetus for tough action.

Pictures of the capital's skyline - buildings mere shadows amid the ghostly grey smog - do not make us think of a nation that is confidently forging into the future. But clearing the air will not be as easy as during the Olympic Games in 2008, when normal life was all but brought to a halt. Ringed by mountains that trap pollution, its roads choked by traffic and, in winter, locked in a chill, it represents a significant challenge. If clean-up measures are to be resolutely taken on, though, there is no better place to be a showpiece.