Hangzhou, China - Ahead of the G20 summit set to begin here this weekend, more than 2 million residents of this eastern Chinese city have gone on holiday - subsidised by the government.

The city government ordered one week of vacation and distributed travel coupons worth more than $1.1 billion.

As a result, about one-third of the city's population has left ahead of the meeting of world leaders, which is set to take place on Sunday and Monday, Chinese travel agency Ctrip estimated.

It's the first time China will host the annual summit, and Beijing is keen that it goes off without a hitch.

City streets won't only be devoid of people, but also of cars, with the government banning about half of car transportation. Production at factories in a 300-kilometre radius around the city was also shut down, allowing the smog to clear.