The city's first law to ban smoking in public places takes effect today with offenders facing fines from 50 yuan (US$7.32) to 200 yuan.
The ban applies to 12 types of public areas, including schools, hospitals, supermarkets and elevators.
The law also requires karaoke bars, dance balls and restaurants to set up designated smoking and non-smoking areas.
However, the law's critics say the penalties are no more than empty talk, as the feasibility of law enforcement has been questioned not only by the public but even by supervision officials themselves.
One of the main problems is that the smokers can easily leave the scene long before the arrival of the law enforcement officials.
That is because neither the smoking-control volunteers nor the area's supervision officials have the right to detain offenders even if they refuse to stop smoking.
All they can do is dial the public supervision hotline to report offenders, and wait for the law enforcement units to take over the case and determine the fine, but the whole procedure is complicated and time consuming.
"I don't think the law was mainly aimed at fining the offenders, but more like a warning to them," said Xiong Bianfeng, director of smoking-control at Jiangsu Road neighborhood committee.
"The law helps to create an anti-smoking atmosphere in public venues and encourage people to police themselves. It is far more meaningful than simply conducting penalties."
Xiong said he believed fewer people would smoke in public with the issue of the new law, as the smoking-control message had been well publicized.
"Only those who are too eager to get famous would dare to smoke with millions of eyes staring at them," Xiong said.
Another problem causing difficulties for law enforcement is that many restaurant owners or service industry companies are afraid of losing customers, so would refuse to report offenders.
"We would try to politely persuade a smoker to enter a smoking area, but we cannot do anything about it if the smoker refuses," said an assistant surnamed Chen at the Ever Shining Circuit Cinema.
Shanghai issued a rule banning smoking in some public places in 1994 and amended it in 1997.
That banned smoking in hospitals, schools and kindergartens, indoor stadiums and larger stores.