To do that, she's focusing on the people who grow tobacco, not on those who use it.

"Everyone already knows the health argument against smoking, so the really important thing in China is making the economic argument," says Judith MacKay, a Hong Kong doctor who advises the World Health Organisation and World Lung Foundation.

Li is trying something new, showing "tobacco control measures need not necessarily harm its economy and the farmers".

Her idea is to start a revolution among China's 20 million tobacco growers that will deprive China National Tobacco Corp, which manufactures two of every five cigarettes consumed on the planet, of the raw materials it needs. Li figured approaching the predicament from the agriculture side would be palatable to decision-makers, who are perennially preoccupied with how to feed the country's 1.3 billion people.

In a crop-replacement pilot project she lead with farmers in Yunnan province, they made more money after switching to producing food. She figures if enough others follow suit, China National will have to turn to more expensive sources. It will be forced to raise prices, goading smokers to quit. Governments will have to find other tax revenue. The industry's influence will weaken.

It's a theory Li cautions can't be implemented too swiftly. "If tobacco farms are fully eliminated right away," she says, "it will create chaos".

China, with about 320 million smokers, is hooked in more ways than one. The country is the world's biggest tobacco producer, and tobacco taxes account for 7 per cent of the government's revenue, bringing in about US$100 billion in 2012. Some cities in farming regions rely on tobacco duties for almost half their budgets. There's a 23 per cent levy on cured leaf sales, the only crop on which farmers are taxed.

Resistance to cutting back is practically built into a government-backed web of interconnections and contradictions. China National's deputy director is Li Keming, the brother of Premier Li Keqiang, who as head of the cabinet is the official ultimately in charge of health care. The company's parent, the Ministry of Industry and Information Technology, directs the body responsible for implementing a treaty with the United Nations in which China promised to reduce the harm from tobacco.

The State Tobacco Monopoly Administration regulates the production and marketing of cigarettes - and is headed by the same group that runs China National.

"China faces intractable political, structural, economic and social barriers in tobacco control," says Hu Teh-Wei, a professor in the school of public health at the University of California, Berkeley.

The country has plenty of reasons to kick the habit. Cancer, diabetes, heart disease and other ailments tied to smoking will crimp national income by US$558 billion in the decade ending in 2015, the WHO predicts. About one million people die of smoking-related causes every year.

For Li, the millions of tobacco growers, most with plots of just a hectare or two, are as important.

"I was concerned about the tobacco farmers because how could they ever become rich with that little piece of land?" Li says on a bumpy ride in the back of a minivan in rural Yunnan. She visits twice a year to see the progress of former tobacco growers and check on other projects, including her latest, installing eco-toilets in schools.

With funding from the Hung and Jill Cheng Charitable Foundation, started by a family friend, US$15,000 of her own money and help from local government authorities, Li persuaded 458 farmers in the corner of southwestern China to spurn the fragrant leaves in 2008 in favour of grapes, mushrooms and other new food crops.

After four years, everyone was making more money, Li says on the ride through Changning. Grape growers sold US$15,000 on average from every acre planted in 2010, pocketing US$10,175 in profit, more than double the return on tobacco, according to Li. Those who switched to mushrooms reaped 80 per cent more annual net income than neighbours who stuck with tobacco. Their average annual profit was just US$4,834.

Now it's harder to get people with land on the plateaus of Yunnan to grow tobacco, says Xia Ning, deputy director of the industrialisation office at the Bureau of Agriculture in Yuxi, which worked with Li on the crop replacement pilot project.

"Other farmers saw the results and also came to us wanting to switch," Xia says. So many have abandoned tobacco since that cigarette makers hired labourers to plant the crop on farms that shunned it, he says, and the recalcitrant farmers would turn around and dig up the unwelcome seedlings in the night.

The agriculture bureau took something of a daring step when it teamed up with Li. The bureau is based in the same city as Hongta Tobacco Co, a China National unit that makes the country's top-selling brand, Hongtashan, and is a main buyer of the crops the bureau encourages farmers not to plant. Hongta's net income in 2012 was US$992 million.

The centrepiece of the garden at the base of Hongta's 23-storey office tower is a giant silver pipe that puffs out wisps of grey smoke. Near the entrance to the Hongta tobacco culture museum, open five days a week, stand eight golden pillars in the shapes of cigarettes.

This is tobacco country, but Xia says he hasn't encountered opposition to the crop-replacement endeavour "because this is still on a small scale". Come what may, he says, the government has told the bureaus to help farmers improve their livelihoods.

It helped shield the bureau, according to Li, that she lent her name and UCLA's to the project.

Some powerful locals endorse what she's doing; one is Wu Kunyi, a senior health official when Li met her as she started travelling to China in the 1980s to work on public health projects, building the connections to tackle tobacco. Li says Wu introduced her to Yuxi's top-ranking Communist Party leader, who gave the pilot project the go-ahead.

The tobacco monopoly's local bureaus might be Li's main hurdles. Beijing sets local quotas for land that can be used for tobacco production and fixes the price China National pays for cured leaves, and the monopoly bureaus are responsible for securing the raw materials.

"They can't force farmers to plant tobacco, but if the village committee is given a quota for tobacco leaves, then there is pressure," Xia says. "If I'm a village official and a farmer refuses my instruction to plant tobacco, I could say, 'All right then. If you need help in future, don't come looking for me'. And some farmers will still do it out of fear."

The tobacco bureau in Yuxi took a page from Li's book in 2010, approaching a group of farmers with a plan to boost annual yield by consolidating small plots to reap economies of scale. The bureau also offered technical assistance as part of a five- year deal to sell leaves to cigarette makers, according to Yin Wenyu, deputy leader of the group.

It lost money early on, due in part to a drought. Disappointed, Yin says he and his fellow farmers set aside 50 of their collective 250 hectares to experiment with grapes in 2011, and liked what they saw.

"The returns from grapes are looking quite good even though the initial investment was much larger," Yin says.

The group plans to increase the area planted with grapes, which may mean ending their relationship with the tobacco industry.

"The company raised the tobacco leaf purchase prices 10 to 20 per cent each of the past two years after many years of no adjustments, but it's still not enough to meet our needs," Yin says, puffing on a cigarette as he oversees workers weighing and packing freshly picked grapes.

China National's Yunnan branch is also trying incentives. Four years ago, company representatives began building curing centres around Jifei, a village of 2,000, says Yang Dewen, the village Communist Party secretary. The company funded 90 per cent of the cost, with the county government kicking in the remainder, Yang says during a tour of a 12-shed curing facility opened last year. The complex backs onto Yang's two-hectare plot, enabling him to avoid the home curing that limited how much he could grow. "When we were on our own, I could only manage to plant tobacco on less than 1 acre a year because I had a small curing room," he says. "But now I can plant tobacco on 2 acres because I don't have to worry about the curing."

Across Jifei, tobacco growing has more than doubled to about 250 hectares since the curing centres opened, Yang estimates. While some of his neighbours have experimented with fruit and flowers, he says those enterprises aren't likely to be successful because the village is too remote to get fresh produce to market.

In Beijing, the health commission is drafting a proposal for a national ban on lighting up in public that could help cut smoking rates and ease the pressure on tobacco farmers.

Wu Kunyi, the Li supporter and former leading member of Yunnan's top political consultative committee, says that she's hopeful. "Tobacco substitution is going to be very difficult, but it's something we need to try so we can develop in new ways," she says.

"As more farmers and people in government see that substitution works, we can slowly reduce China's dependence on tobacco."