By Jill McGivering
Smoking is deep-rooted in Chinese culture
A ban on smoking in most public buildings has come into force in the Chinese capital, Beijing.
The move is an attempt to discourage some of China's 350 million smokers and also part of wider efforts to clean up the city in the run up to the Olympics.
For every three cigarettes lit worldwide, one is smoked in China. Almost 25% of the Chinese smoke.
Smoking is also contributing to a rapid rise of cancer and heart disease in the world's most populous country.
In Beijing, the smokers are everywhere - and it feels like it. But now that may change.
The city authorities have imposed a ban on smoking in most public buildings.
They say they are organising 100,000 existing employees to act as an enforcement team.
The authorities had wanted restaurants and bars to be mostly smoke-free as well, but there was too much resistance.
Instead, they must provide non-smoking areas or rooms.
"If measures are not taken, with so many smokers in China, in 10, 20, 30 years, the health system will have even higher burden to manage patients with cardio-vascular diseases, with cancer and so on," says Dr Hans Troedsson, the China representative for the World Health Organization.
"So it's a kind of sub-acute health threat here in China," he says.
The imminent Olympic Games have also strengthened motivation.
China wants to promote Beijing as a progressive, modern and clean city.
Less smoke and fewer cigarette butts could really help.
Smoking is deep-rooted in Chinese culture and there is still a general lack of awareness about the impact on health.
The WHO is discussing further measures with the government, like an increase in taxes on cigarettes.
But smoking is big business, and some officials are worried about damaging that.
However, financial loss now could be more than off-set by savings on health care in the future.