During China's uphill battle against its appalling air pollution, a consensus is urgently needed that inaction is no longer an option.

Smog has been shrouding large swathes of northern China, including Beijing, since early this week. The affected area reportedly extends 1 million square kilometers.

Even worse, this is the fourth smog this winter that has reduced visibility to such a level that, as one online wit suggested, a couple cannot even see each other's face when they stand hand in hand.