Some passengers were observed eating in Shanghai's subway cars on Thursday, the first working day after a measure frowning on the practice took effect.

The Shanghai Municipal Transport and Port Authority is asking passengers to avoid eating while riding, but also to refrain from other behavior that could annoy their fellow travelers.

The new measure covers skating in stations, carrying super-size luggage, smoking and a host of other acts. It was approved in December and took effect on Jan 1.

Of all the topics, eating was the most controversial. After heated debate about whether a ban should be written into regional regulations, which carry the force of law and include penalties, the authorities compromised.

As enacted, the new rule asks passengers to avoid eating in train cars as a matter of courtesy to others. It does not require them to refrain, nor is any penalty imposed for noncompliance.

Eating inside subway stations was not banned.

Supporters said that passengers who eat on train cars annoy others with unwanted odors and make messes with spilled food or beverages.

Opponents, by contrast, said the fast pace of big cities squeezes people's time and makes it hard to get a proper meal. Authorities should be more tolerant of those who need to dine on the train, they said.

Nationwide, cities such as Beijing, Guangzhou and Nanjing have enacted similar rules to ban eating in subway cars. Wuhan, capital of Hubei province, is the only city so far to use a regional law to clamp down on the practice.

In Shanghai, a random survey by China Daily on Thursday morning found that people were largely unaware of the new guideline, though many said they were willing to abide by it.

Not everyone thought it was a good idea.

"Society should be more tolerant of those having to eat on the train," said Wu Fangcheng, 27, an IT company employee who was having bread and milk inside the Changshu Road station on Line 1.

He said he preferred to spend more time sleeping in the morning, even if that meant crunching his time for breakfast. But the arrangement is less than ideal.

"If possible, who would not sit down with their loved ones to have a decent breakfast? It's not comfortable to eat in a swaying train," he said.

Another passenger, who was having a sandwich and yogurt on Line 7, said he was not aware of the rule but would like to follow it.

"The request won't cause much problem for me. I usually finish my breakfast at the station in a very short time," said the man, who declined to be identified.

Bert Quintens, a tourist from Belgium, said he doesn't find eating by fellow passengers offensive.

"In Belgium, eating on public transportation is also prohibited, but people keep ignoring the rule," he said. "Nobody would stop them, and it is very hard to do so. I think it is acceptable as long as you don't leave any garbage."

A dispatch operator at the Changshu Road station, surnamed Yang, said on Thursday that he will intervene to block some discourteous acts in the subway such as smoking or boarding with a pet, but he will not step into a car to stop someone from eating.

Shanghai Shentong Metro Group, the sole operator of the city's subway network, gave no specific directions as to enforcement of the new rule, Yang said. "It is OK as long as no one complains about it."

Wu Junshang, a manager of passenger service at the Shanghai Metro Operation Management Center, said the no-eating rule may not be very effective since it is not compulsory. At the same time, it would hard to enforce if it is included in the regional law, Wu said.

On Thursday morning, shops and vendors selling food inside or near subway stations in Shanghai were still popular.

One vendor near the Zhaojiangbang Road station on Line 7, who gave her name as Zhang, said she was sold out of rice rolls (she started with 40) by 9 am.

"It's because there is a large passenger flow on the first working day after a holiday, and the warm weather makes people willing to stop and buy food," she said.

Qian Zhaocheng, a commentator, said authorities should consider the needs of different groups of passengers. He does not support a law that reaches too far — such as a broad ban on eating in subway cars — he said.

"It's not people's own choice," he said. "The great pressure of living requires many people to spend their dining time on the subway."

wangzhenghua@chinadaily.com.cn