Qu Jun, an official with the Standing Committee of the Shanghai Municipal People's Congress, said the law introduced a system of co-peration between 10 government departments involved in tobacco control enforcement and inspection.

"The work cannot be done by a single department," he said.

The People's Congress also strengthened inspection of the enforcement of the ban on smoking.

"We generally review the implementation of laws and regulations after they have come into effect for one or two years. But in this case, we carried out the first inspection in August," Qu said.

However, problems still exist. For example, Zheng Pinpin's research showed that the situation was not 100 per cent satisfactory in the outdoor non-smoking zones, as smokers were still found in 18 of the 26 outdoor rest areas at the Expo park.

One of the world's largest tobacco-producing and consuming nations, China manufactures about 100 billion packets of cigarettes each year. Further, it has a smoking population of 350 million, about one-third of the world's total smoking population.

Xu Guihua, vice president of the Chinese Association on Tobacco Control, said Chinese smokers still have little understanding of the risks of smoking, as many of them believed that there was "no danger if you smoked less" or smoked "low-risk cigarettes with low tar concentration". Both assumptions have already been proved wrong.

"There's still a long way to go towards controlling tobacco use in China," said Xu.

Nevertheless, China, which ratified the WHO Framework Convention on Tobacco Control in 2005, has certainly made great efforts to control tobacco use.

Sarah England said smoke-free Expo set a good example and proved that a smoke-free environment could be achieved in China.

"It's a ray of hope for a smoke-free China," she said.

She said the model of continuous review and improvement and making step-by-step progress was good and should continue in the future.

Li Xinhua, an official with the Ministry of Health, said the Ministry planned to ensure that officials learned from the experience of Shanghai, so that they could improve on their nationwide efforts to curb tobacco use.