Also, it keeps the brand out there

Chinese state media come up with a whole list of the various benefits of smog.

On Monday the website of China's state broadcaster CCTV published a list of five "unexpected benefits" brought by the crippling smog.

It said the haze had unified Chinese people, as they find solidarity in their complaints; equalised them, as both rich and poor people are vulnerable to its effects; enlightened them, as they realise the cost of rapid growth; and "made Chinese people more humorous", as smog-related jokes proliferate on the internet.