Researchers expect that within a few decades, the pro-portion there will rise to about one in three, as it did in the United States. In contrast, smoking among young Chinese women has not increased markedly in the past two decades, and most of those women who do smoke are older. Thus, on current smoking patterns, female tobacco-attributable deaths in China may actually drop from their current level of about 2 percent of the total to less than 1 percent. Researchers calculate the excess risk of death in smokers through prospective studies that compare the health outcomes of smokers and nonsmokers. Smokers in the United States are 20 times more likely to die of lung cancer in middle age than nonsmokers and three times more likely to die in middle age of vascular diseases, including heart attacks, strokes, and other diseases of the arteries or veins.
Smoking is also the leading cause of chronic bronchitis and emphysema.
It is associated with cancers of various other organs, including the bladder, kidney, larynx, mouth, pancreas, and stomach. A person's risk of developing lung cancer is affected more strongly by the amount of time that they have been a smoker than by the number of cigarettes they have smoked daily. Put differently, a threefold increase in the duration of smoking is associated with a 100-fold risk of lung cancer, whereas a threefold increase in the number of cigarettes smoked each day is associated with only a threefold risk of lung cancer. Thus those who start to smoke in their teens and who continue face the biggest risks. The data from China suggest that deaths from ischemic heart disease make up a much smaller proportion of the total number of deaths caused by tobacco than in the West, while respiratory diseases and cancers account for most of the deaths.