We worked on this report about Health Insurance and the cost of smoking in 2012.
The conclusion of this report was that cigarette smoking is a health hazard of sufficient importance in the United States to warrant appropriate remedial action. The evidence proved that cigarette smoking contributes substantially to mortality from certain diseases and to the overall U.S. death rate. In the 47 years since this report was published, hundreds more studies have been released building upon and re-confirming the original findings. The main conclusion of these studies is that tobacco and tobacco products are dangerous to smokers and persons who are subject to secondhand smoke.
Read the full document here