More than 400,000 Beijingers have joined an online discussion about whether to keep traffic restrictions introduced for the Olympic and Paralympic Games.

Nearly half of those taking part wanted to see the restrictions - an alternating odd-even license plate system - become a permanent fixture.

Unsurprisingly, motorists account for most opponents of the measure that has been in force since July 20.

"I support long-term car restrictions. We have made some mistakes in the past. Now we should correct them and return blue skies to our children," wrote He Luzhu on a forum on www.ynet.com, the website of Beijing Youth Daily.

Air pollution and traffic jams emerged as key problems in 2001 for Beijing's bid to host the Games, said Sun Daguang, who was once vice-secretary of Beijing 2008 Olympic Games Bid Committee.

Highlights of the city's seven-year effort to cut pollution were the relocation of giant steel company Shougang and the traffic measures that have kept around 2 million vehicles off the road.

Taxis, buses and other public-service vehicles were exempt from the restrictions. "The sky was blue during the Olympics. It's so much better than those foggy days," said a repair worker surnamed He.

But people who opposed a long-term car ban argued it was a sticking-plaster solution.

"Only after the government makes great progress in improving public transportation should we discuss whether to keep the restrictions. I love blue skies very much. But I had to drive a car because I could not stand being packed in a bus for six hours a day," said an anonymous netizen.

Official statistics showed the city's roads were extending at an annual rate of 3 percent while the number of vehicles was increasing at about 15 percent per year.

"When cars run at low speeds in traffic jams, they emit many more pollutants and usually consume more fuel," said Hao Jiming, a member of the Chinese Academy of Engineering.

Many people who had initially expressed annoyance over the restrictions are now unwilling to return to days of choking smog and rush-hour congestion when the restrictions end after the Paralympics.

Beijing's traffic authority said it has received many submissions from car owners comfortable with the restrictions and hoping they will continue.

The city will continue to improve its public transport service by expanding transport networks and keeping fares low after the Olympics, said Zhou Zhengyu, deputy director of the Beijing municipal committee of communications.

"We aim to create a more convenient and comfortable environment for people traveling in the city," he said.

The car ban might be a cure for congestion but not necessarily the best one, said Yang Kaizhong, an economist from Peking University.

He argued there were a variety of methods, such as congestion charges and raising parking fees that have proved effective in some foreign countries.