Marveled by the futurist architecture, Jiang lit up a cigarette as he disembarked a tourist bus in front of the National Center for the Performing Arts (NCPA), situated in the heart of Beijing.

"It is my first time to the grand theater," said the 60-year-old farmer from east China who only gave his surname Jiang, referring to the French-designed new icon of the Chinese capital.

Jiang, excited to explore, strode into the hall, with the burning cigarette still in hand. No one bothered to stop him as he puffed away.

Such an example demonstrates the huge challenge Chinese health authorities face in imposing a smoking ban in all enclosed public venues in a country with the world's largest number of smokers -- 350 million -- and a deep-rooted tobacco culture.

Smoking-related diseases kill roughly 1.2 million Chinese every year and the death rate is expected to keep climbing in the coming decades, according to estimates of the World Health Organization and Chinese health authorities.

The new ban to be effective on May 1, issued by the Ministry of Health in March, is the latest government response to curb tobacco use.

But experts say the ban is more likely to be ignored by smokers, public venue operators, and the general public due to its vague content, namely it fails to specify adequate supervision measures and punishments for violations.

"I don't know about the ban," said Jiang, a smoker for nearly 40 years. "I'm very addicted to the habit, but I would not have smoked here if someone told me not to."

At the NCPA entrance and its main hall where Jiang lit up, no obvious No Smoking signs are in sight. Outside the NCPA, the pedestrian walk leading to the Tian'anmen Square is littered with cigarette butts.

Tourists are also seen lighting up in the crowds between Tian'anmen Square and the Forbidden City, facing the giant portrait of late leader Chairman Mao Zedong who was a heavy smoker himself.

The Health Ministry's smoking ban also stipulates that business owners of places frequented by the public should set up conspicuous non-smoking signs, carry out promotional activities to warn people of the dangers of smoking, and dispatch personnel to dissuade smokers.

Further, designated outdoor smoking areas should not be located on public pathways and cigarette vending machines should be excluded from public places, according to the ban.

Calling it an important progress, Yang Gonghuan, deputy director of the Chinese Center for Disease Control and Prevention, said the ban is however hastily enacted as no significant improvement has be achieved in the two months after the ban was announced.

Yang, a leading Chinese tobacco control expert, said "it takes a long time" to train smoking ban enforcers, set up active supervision hotlines, and raise the public's awareness to the point that mass supervision and smoker self-restraint can effectively work.

Yang said the ban's major weakness is that its current form does not stipulate punishments for violations and the part of enforcement and supervision also needs to be backed by strong and concrete clauses in future revisions.

China does not have a comprehensive national law on tobacco control. Smoking is most strictly banned by government regulations in hospitals, schools, and on public transport vehicles.

But a visit to Beijing Children's Hospital reveals that banning smoking is not easy.

Migrant construction workers are seen lighting up occasionally in the men's toilet of the otherwise apparent smoke-free hospital compound.

"I know smoking is bad, especially in a hospital, but I just could not resist the urge," a migrant worker told Xinhua while smoking in the toilet. "The toilet is the only place in this building where I can smoke without being interfered with," said the migrant worker who did not want to be named.

In Beijing, high-end hotels, department stores and restaurants have imposed strict bans on smoking, while owners of many back-street eateries say they would risk bankruptcy if the smoking ban is enforced.

Restaurant owners in Xidan, the central shopping district of Beijing, say they have not received any order from government administrators to ban smoking in their premises by May 1. And they will follow others when the ban eventually takes effect.

China rectified the WHO Framework Convention on Tobacco Control in 2003, but implementation of the treaty was slow over the past few years, health experts say in a report published earlier this year.

Yang, a lead writer of the report, said government policy is one but not the only important part of tobacco control initiatives. Raising public awareness remains the key to success.

A survey conducted by the China CDC shows that only 25 percent of Chinese know exactly the harms posed by smoking and second-hand smoke.

"Without a successful mass campaign, tobacco control is doomed to fail," she said.