According to the Center for Disease Control and Prevention, smoking is the leading preventable cause of death in United States. The World Health Organization list tobacco use as a risk factor for the leading causes of death, accounting for some 6 million deaths per year worldwide. Smoking increases the risks of diseases such as coronary heart disease, stroke and several types of cancers in addition to being responsible for overall diminished health and fitness. In many countries in the developing world smoking rates are now declining. However, cigarette smoking remains a major public health challenge and reduction or elimination of tobacco smoking is a priority for public health.