Beijing banned more than one million cars from its roads yesterday in a test run to improve air quality for the Olympics, easing gridlock but failing to lift a curtain of smog from the capital.
More than 6,500 traffic police were on duty across the city to ensure car owners observed the ban, while an extra 2 million more trips were expected to be taken on subways and buses during the day, officials said.
The four-day test is geared as a prelude for a similar ban to be put in place for the duration of next year's Olympics, as part of a range of measures to temporarily improve air quality for athletes and visitors.
Beijing is one of the world's most polluted cities and poor air quality, blamed partly on the city's 3 million cars -- a number growing by 1,200 a day -- has long been a top concern for athletes and officials.
Those worries were exacerbated as a weeks-long haze that reduced visibility to just a few hundred meters at times marred the build-up to last week's one-year countdown to the Games.
International Olympic Committee president Jacques Rogge, in Beijing for the countdown, said then some events could be postponed if pollution was extremely bad in a move to protect athletes' health.
City officials said they expected the ban to have a big impact, with vehicle emissions to be cut by 40 percent.
"This is a sweeping traffic ban, so the effects on pollution levels are expected to be dramatic," said Du Shaozhong, deputy director of Beijing's Environmental Protection Bureau.
"Today is a good day in terms of pollution. You can go out and do sports or whatever you want," he said.
However by yesterday afternoon the smog, which has become as much a feature of the city as construction workers and new skyscrapers, remained thick.