This is the 30th tobacco-related Surgeon General’s report issued since 1964. It describes in detail the specific pathways by which tobacco smoke damages the human body. The scientific evidence supports the following conclusions: There is no safe level of exposure to tobacco smoke. Any exposure to tobacco smoke—even an occasional cigarette or exposure to secondhand smoke—is harmful.
U.S. Department of Health and Human Services. How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease: A Report of the Surgeon General [Internet]. Atlanta (GA): U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health; 2010 [cited 2013 Jan 19]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK53017/pdf/Bookshelf_NBK53017.pdf