SANAA With bloodshot eyes and brown-stained teeth, the suit-clad civil servant gazes at the floor, his right cheek bulging with a tennis ball-sized wad of bright green leaves.
Every day after lunch, 38-year-old Ali returns to his office at the Passport and Immigration Authority in Sanaa to spend the rest of the day with colleagues chewing qat.
"It is the flower of paradise," he says, one of four lounging on cushions on the office floor amidst a clutter of laptops, soft drinks, ashtrays and water-pipes. "As Yemenis, it runs in our blood, it's what makes us tick."
Like others plastered on the walls of libraries, mosques, coffee shops and cafeterias across Yemen's capital, a poster on the wall reads "Lead by Example".
"No more chewing in the office."
Chewing on qat, or 'takhzeen' in Arabic, has been a national pastime in Yemen for centuries.
But a few activists are determined to stamp out the practice, convinced that the chewing and production of qat, which is dominated by the country's tribal leaders, military officers and politicians, is stifling Yemen's potential while depleting the country of its few remaining natural resources.
One in every seven working Yemeni is employed in producing and distributing qat, making it the largest single source of rural income and the second largest source of employment in the country after the agriculture and herding sector, exceeding even the public sector, according to the World Bank.
Many of Yemen's poorest families admit to spending over half their earnings on the leaf.
"Qat is the biggest market in Yemen, bigger than oil, bigger than anything," said Abdulrahman Al-Iryani, Yemen's former water minister and founder of ‘qat uprooting', a charity which supports farmers in replacing qat shrubs with coffee plants.
"There are rich and powerful people in the government and behind the government, who control it, who benefit from it.
"From the parents who buy qat instead of paying for their kids' education, to the men in hospital with throat and mouth infections draining the health service, to the unemployed who spend eight hours chewing every day instead of searching for work - qat is entwined in all of Yemen's problems."
Yemen's ruler for three decades, Ali Abdullah Saleh, stepped down earlier this year after months of protests, part of the Arab Spring that ousted leaders in Tunisia, Libya and Egypt.
Although some stability has returned, the state is near collapse, its economy is stagnant, al Qaeda militants are expanding their foothold in the south and Houthi rebels have taken over a chunk of the country's north.
The country's most immediate crisis is its dwindling water supply. The capital city Sanaa is predicted to become the first in the world to run out of water, but the cultivation of qat - the least taxed, most subsidized and fastest-growing cash crop in Yemen - consumes 40 percent of irrigated farming land.
One "daily bag" that can be consumed by one person in one day requires hundreds of liters of waters to produce.
Classified as a "drug of abuse that can produce mild to moderate psychological dependence" by the World Health Organization, qat's physical symptoms can include high blood pressure, tooth decay, constipation, hemorrhoids, hallucinations and depression.
Surveys suggest that more Yemenis than ever - at least 80 percent of men, about 60 percent of women and increasing numbers of children under 10 - settle down most afternoons to chew.
"Qat is to Yemenis what coffee is to Americans and tea is to the British," said young qat merchant Faris al-Raymi. "It's part of everyday life."
The latest anti-qat effort was adopted by the government on April 12 after months of pressure from female activist Hind Al-Iryani who, using Twitter and Facebook, managed to push the issue on to the national agenda and marshal substantial support amongst young Yemenis in favor of a total ban.
Iryani and a group of Yemeni lawyers have presented a draft law to the prime minister that would impose penalties on those expending public resources on or consuming qat in governmental offices.
"If the law was passed it would send an immediate and clear message to all Yemenis that qat chewing is neither acceptable nor appropriate in the world of work," said Iryani.
"The government should start by getting their own house in order, being role models to other citizens."
The campaign, through state broadcasters, handouts, posters and workshops, is the first concerted effort by the state to tackle the drug's use in more than a decade.
But many Yemenis say they can't help but feel this campaign will fail, like others before it.
In 1972, then-Prime Minister Mohsin Al-Aini forbade qat-chewing by public servants during working hours and banned its cultivation on lands run by state-controlled religious trusts.
He received death threats from tribesmen and qat farm owners around Sanaa. Many Yemenis suspect his eventual dismissal from office three months later was in large part due to his push.
"The reason previous attempts to curb the drug have failed is because they run up against the political establishment, many of whom have invested interests in the lucrative qat industry themselves. They preach but they refuse to practice," said Abdullah al-Faqih, professor of politics at Sanaa University.
Like a runaway train hurtling towards a precipice, many worry that there doesn't seem to be any way to stop qat pushing Yemen into disaster.
"It's a vicious circle," said Mohammed Al-Saidi, an American-educated economist and former head of the country's water authority.
"As water prices go up, the competition drives more and more people toward farming qat which in turn uses up even more water. If the spread of qat farms continues like this soon all our arable land will be used to grow qat."
Al-Iryani said government officials were too involved in the industry to be enthusiastic about stamping it out.
"They don't want to fight it, they want to encourage it," he said. "I have never met a government official who is wholeheartedly against qat."
In the bustling qat souks tucked behind the ancient tower houses of old Sanaa, mention of the government's latest efforts is met with guffaws.
"Qat is a way of life. It determines the rhythm of the city, from the time people leave work, to the intensity of traffic jams," said qat-seller Ahmed Zafer, flicking a rug over a mound of pink plastic bags stuffed with the leaves. "It is part of who we are as Yemenis and has been for centuries.
"It is the only thing gluing Yemenis together. It doesn't matter if you're rich or poor, young or old, male or female, everyone chews."
(Editing by Sami Aboudi and Sonya Hepinstall)