Bureaucratic fighting between the environment ministry on the one hand and China National Petroleum Corp and Sinopec on the other has thwarted stricter emission standards for diesel trucks and buses – a main cause of air pollution blanketing dozens of China’s cities.

Mainland refiners, like many before them, now realise that parties don't last forever and eventually everyone has to sober up. The decision by state-controlled giant PetroChina to put off two new refineries and delay expansion of another is the latest, most dramatic signal that the mainland's refined fuels capacity has expanded too fast.