On a recent weekday afternoon in Ho Chi Minh City, the passengers bouncing along on one of the city's green buses breathed in mouthfuls of carbon monoxide, hydrogen cyanide and other chemicals that add to Vietnam's notorious pollution.

The toxic smoke did not come from the bus itself, but from the man driving it — one hand supporting the wheel, the other holding a cigarette.

Vietnam bans smoking on public transit, but that does not stop some of the bus drivers from lighting up on a daily basis. Amid this loose compliance and enforcement of tobacco rules, as well as an increase in overall smoking in the country, the government is looking at another policy option: taxes.

The Ministry of Health has recommended tacking on a levy of 2,000 Vietnam dong (9 cents) to each pack of cigarettes.

Cheap cigarettes

While incomes in Vietnam have gone up in recent years, cigarette prices have been slower to rise, making the tobacco product relatively more affordable than before. For example, per capita income jumped 370 percent in 2005 and 2006, but cigarettes cost just 120 percent more in that period, the government's Vietnam News Agency reported.

FILE - A young motorcyclist stops to buy a pack of FILE - A young motorcyclist stops to buy a pack of cigarettes from a street-side vendor in Hanoi, May 12, 1999. FILE - A young motorcyclist stops to buy a pack of cigarettes from a street-side vendor in Hanoi, May 12, 1999.

Supporters of higher tobacco taxes say that's why the Southeast Asian country must do more to help people kick the habit.

"To quit smoking is not easy," Luong Ngoc Khue, director of the Tobacco Control Fund at the health ministry, said on national broadcaster VTV. "However, sanctions in Vietnam have not reached the level hoped. In other countries, there are strict penalties. But in Vietnam, enforcement is difficult, even though we have the laws."

Restaurants, bars and clubs are a case in point.

Authorities prohibit smoking in these and other public places, but business owners continue to provide ashtrays to customers.

40,000 deaths

This flouting of the law contributes to the 40,000 tobacco-linked deaths that Vietnam sees each year, the World Health Organization estimates.

A single pack can cost about 10 times less in Vietnam than it does in nearby Singapore.

The defiance of the law underscores how hard it has been for Hanoi to curb the country's nicotine addiction. The government has tried other ways to influence public behavior, including a ban on tobacco sales to those under 18 years of age; no sales near hospitals and schools; not allowing industry advertising; and the introduction of graphic health warnings on labels.

There have even been groups of young campaigners donning blue shirts and biking through the Vietnamese streets to raise awareness, a common form of public service announcements in the country.

'Tobacco breaks hearts'

Worldwide, nearly a third of deaths stemming from heart problems are connected to smoking, the WHO said.

FILE - A cigarette seller, right, waits for custom FILE - A cigarette seller, right, waits for customers by Hoan Kiem lake in Hanoi, Vietnam, June 27, 2017. FILE - A cigarette seller, right, waits for customers by Hoan Kiem lake in Hanoi, Vietnam, June 27, 2017.

"In Vietnam and other places, many people might be aware that smoking can harm their health, particularly associating smoking with lung cancer and respiratory diseases. Many smokers and nonsmokers alike, however, still lack awareness of the impact of smoking on heart health," said Kidong Park, the WHO representative in Vietnam, explaining why the agency chose the "Tobacco Breaks Hearts" theme for this year's anti-smoking efforts.

The WHO also warned that tobacco hurts economies through the cost to public health and lost workforce productivity.

TPP and tobacco

If nothing changes, Vietnam could see an increase in smoking.

Vietnam is one of 11 countries that remained in the Trans-Pacific Partnership after President Donald Trump withdrew the U.S. from the trade deal in 2017. The World Bank said in a 92-page report in March that the tobacco industry will be one of the big beneficiaries of TPP tariff reductions, along with the food, beverage and agriculture sectors.

While the U.S. is not in the TPP, it is still benefiting from trade growth. The U.S. exported $10 million worth of tobacco to Vietnam in 2016, an increase of more than 250 percent compared with shipments in 2012, according to the U.S. Department of Agriculture.

Last year, the Southeast Asia Tobacco Control Alliance criticized the U.S. embassy in Hanoi for including the Philip Morris tobacco company in a trade mission with the Vietnamese prime minister.

"It is unfortunate that although the U.S. is only one of two countries in the world [Britain is the other country] that has good laws to prohibit their diplomatic missions from being used to promote tobacco, a tobacco company can still meet with a country's top leadership through an event promoted by the U.S. embassy," SEATCA said.