The scope of the burden of disease and death that cigarette smoking imposes on the public's health is extensive. Cigarette smoking is the major focus of this chapter because it is the central public health problem, but the topics of secondhand smoke exposure, smoking of other combustible tobacco products, smokeless tobacco, and electronic nicotine delivery systems (ENDS) are also considered. The magnitude of the public health threat posed by cigarette smoking stems from two factors: (1) the prevalence of cigarette smoking is so high, and (2) smoking causes so many deleterious health effects. A policy change that reduces the prevalence of cigarette smoking will result in a commensurate reduction in the population burden of disease and death caused by cigarette smoking. The associations between cigarette smoking and the adverse health effects caused by smoking are dose-dependent (HHS, 2014). Thus, a public health benefit would be realized if a policy change led to reduced exposure to cigarette smoke via means other than reducing the prevalence of smoking. For example, additional reduction in the population burden of smoking-caused disease and death will be generated if the policy also results in delayed initiation of cigarette smoking. The population health benefit from delayed initiation, although potentially large, will be less than the benefit from a commensurate reduction in smoking prevalence because delayed initiation is associated with reduced exposure to cigarette smoking rather than with the complete prevention of the exposure. A decrease in the prevalence of cigarette smoking will have additional downstream benefits by reducing the potential for nonsmokers to be exposed to secondhand tobacco smoke.
Cigarette smoking causes chronic diseases that appear at older ages, such as lung cancer, as well as adverse health effects that occur in the short run. The immediate and short-term adverse health effects of cigarette smoking are less likely to be directly fatal than the long-term health effects. Nevertheless, they are important public health indicators because they lead to suboptimal health status throughout the life course in smokers and because many of the short-term physiologic effects mechanistically contribute to the etiology of smoking-caused diseases that usually do not become clinically apparent until later adulthood.
The short-term adverse health effects caused by cigarette smoking can be observed in smokers immediately or soon after they begin smoking. The health effects of cigarette smoking thus begin at or near the age of initiation of cigarette smoking, which is usually in adolescence. To highlight the immediacy of the adverse impact of smoking on health, this report uses a life-course perspective by considering health effects of smoking according to the various stages of life, which include childhood, adolescence, and young adulthood as well as middle and late adulthood, when most of the chronic disease burden imposed by smoking occurs. A particularly vulnerable time during the life course is pregnancy (for both mother and fetus) and the months following birth (for the infant); for this reason, this stage of life is considered separately. In this report, the term “immediate health effects” refers to effects that occur within days of cigarette smoking, while “long-term health effects” refers to the clinical morbidity and mortality that occur primarily in middle and late adulthood, and the term “intermediate health effects” is used to refer broadly to the health outcomes that occur between the immediate and long-term health effects.