Chinese men now smoke one-third of all the world’s cigarettes, and a third of all young men in China are doomed to eventually die from the habit, scientists in China and Britain have concluded.

Their study, published last week in The Lancet, estimated that two-thirds of all males in China smoked, more were still taking up the habit and more were starting as teenagers, which adds risk.

With population growth stagnant, the number of men 60 or older is expected to double by 2030, and the number dying of smoking-related ailments each year will triple, hitting three million a year by 2050.

More smokers are stopping by choice, the study found, but still only 9 percent did so.

By contrast, smoking rates among women in China have dropped sharply; about 10 percent of older women smoke, but only about 1 percent of middle-aged women do. However, another recent study detected rapid increases among teenage girls in some regions.

Before China achieved prosperity, the Lancet study said, smokers typically started at age 25, more smoked pipes and many could not afford multiple cigarettes every day.

The study estimated future smoking-related deaths from many causes, including lung cancer, obstructive pulmonary disease, stroke, heart failure and other cancers. Lung disease rates are already high in China, even among nonsmokers, owing to urban air pollution and to indoor wood fires used by the rural poor.

The study was led by scientists from China’s Center for Disease Control and Prevention, the Chinese Academy of Medical Sciences and the University of Oxford.

Antismoking efforts in China face a difficult political situation: The central government has a monopoly through the Chinese National Tobacco Corporation, and more than 7 percent of government revenue comes from it.

According to an editorial accompanying the study, myths about smoking persist in China: that Asians are less susceptible to its dangers, that it is an ancient Chinese tradition and that quitting is easy.