BEIJING, June 5 (Xinhua) -- A quarter of a million drivers in Beijing are thought to have left their cars at home on Monday in a bid to help improve the air quality on World Environment Day.

The "no car day," started by 132 automobile associations and the local environmental protection authorities, made the usual 50 traffic jam routes in the rush hours in early morning drop to 48, producing no apparent changes.

Despite fewer cars in some parts of the city, many office workers were still late for work - ten minutes to even one hour.

"I didn't notice the change. The roads were jammed with cars in the morning, just as always," said Sun Jing, a publishing house staff.

Nevertheless, officials and participants cited the move as "a good beginning".

"That is a demonstration of modern, civilized awareness for driving," said Meng Xianlong, director of the Control Center with the Beijing Municipal Traffic Control Bureau.

There are 2.68 million motor vehicles in Beijing and 250,000 fewer won't bring fundamental changes to the traffic congestion, Meng acknowledged.

"But it will play a positive role for easing traffic jams and for long-term environmental protection," he said.

Li Yunwei, a young teacher of the Tsinghua University and a starter of the "no car day" move, has left his car at home since May 28.

"It may help a little to ease the traffic jams, but it will produce real results to reduce emissions of pollutants and will exert a far-reaching influence on promoting the idea of 'green outing'," he said while handing out pamphlets on environmental protection to drivers at a parking lot in front of a garment department store.

"We hope more drivers can learn about 'green outing' and drive cars as little as possible in the future," he said.

The "no car day" move encouraged the drivers in the city to leave their cars at home at least one day a month in a hope to ease traffic jams, reduce noise and improve air quality in the Chinese capital.

Motor vehicle emission has been blamed as the leading cause of Beijing's air pollution,

According to the city's environment department research, Beijing's vehicles spew out 3,600 tons of pollutants each day.

But if each car owner leaves his or her car at home one day in a month, then a total of 36,65 tons of pollutants will be prevented from emitting into the air, according to the calculations of the local environmental protection authorities.

Also Monday, China issued a 45-page white paper "Environmental Protection in China (1996-2005)," the second since 1996, saying that the situation of environmental protection in the country is still "grave."

Air pollution control is among the major tasks for environmental protection work over the next five years, said Zhu Guangyao, deputy director of the State Environmental Protection Administration, at a press conference.

Environmental officials have warned Beijing, the venue for the 2008 Olympics, that it is highly unlikely that the city will hit its target of 238 "blue sky" days this year.

The capital needs at least 22 such days per month from June to December to achieve its aim but that will be very "tough," said DuShaozhong, deputy director of the Beijing Municipal Bureau for Environmental Protection.

Beijing launched the program called "Defending the Blue Sky" in 1998, when the city had only 100 days of blue sky.

Beijing saw only 11 "blue sky" days, or days with fairly good air quality, in April, the least in five years, Du said.

From January to April, Beijing reported only 51 "blue sky" days, 16 less than the corresponding period last year, he said.

"The environmental protection will give long-term support to the 'no car day' campaign," he said. Enditem