In the wake of a spell of hazardous smog, Beijing's traffic authority announced on Thursday the city is likely to trial a congestion charge for road users.

Unfortunately, such a statement is little more than cold comfort for local residents, as this is not the first time that a congestion charge has been put on the government's agenda.

As a metropolis with more than 20 million residents and about 6 million cars, Beijing began considering congestion fees in 2010. In its last five-year action plan on controlling vehicle exhaust emissions, the city planned to introduce a congestion charge for the downtown area this year.