Tobacco
Both direct inhalation of tobacco smoke and inhalation of second hand smoke have significant negative effects on health. The World Health Organization estimated in 2002 that in developed countries, 26% of male deaths and 9% of female deaths were attributable to smoking. Similarly, the United States Centers for Disease Control and Prevention describes tobacco use as "the single most important preventable risk to human health in developed countries and an important cause of premature death worldwide."
