Tobacco smoke contains numerous compounds, the important substances of medical significance being the carcinogens (such as polycyclic aromatic hydrocarbons), irritant substances, nicotine, carbon monoxide and other gases. Cigerette smoking is a well-known major risk factor for premature mortality due to cancer, cardiovascular disease, and chronic obstructive pulmonary disease. There is also evidence that passive smoking may contribute to atherosclerosis by sensitizing neutrophils, causing their activation and subsequent oxidant-mediated tissue damage. To achieve a meaningful reduction in the burden to society of coronary heart disease, both passive and active cigarette smoking must be targeted. Many children are regularly exposed to cigarette smoke at home or in other environments, such as child-care facilities and schools. The only safe way to protect nonsmokers from exposure to cigarette smoke is to eliminate this health hazard from public places and workplaces, as well as from the home.