Beijing's authorities have confirmed they are planning to keep a million cars off the city's roads next month to test what effect it has on pollution.
China's government wants to ensure air is clean for the Games
The trial is designed to check whether it would be worth limiting the traffic during the 2008 Olympics in Beijing.
The figure is said to represent about a third of Beijing's car population and the trial will last two weeks.
The International Olympic Committee has welcomed the plan, amid concerns about the levels of air pollution in Beijing.
"Concerns [over pollution] within the IOC executive board were eased," the committee's director of communications, Giselle Davies, told reporters on Monday, after receiving a progress report from Beijing organisers earlier in the day.
"They have a plan from 7-20 August this year: one million cars will be off the road," she said.
The ban follows successful results from a smaller trial last year, during a summit of Chinese and African leaders.
Many analysts believe China could overtake the US this year as the world's largest emitter of greenhouse gases.
China is already reported to have spent about $15m on a massive clean-up in the run-up to the Olympics, including moving steel mills and power plants outside the city limits.