4th on 21 interesting Facts About the U.S.A: Exposure to Secondhand smoke causes nearly 50,000 deaths each year in the U.S. alone.
Overall mortality among both male and female smokers in the United States is about three times higher than that among similar people who never smoked.
The major causes of excess mortality among smokers are diseases that are related to smoking, including cancer and respiratory and vascular disease.
Smokeless tobacco is a known cause of cancer. In addition, the nicotine in smokeless tobacco may increase the risk for sudden death from a condition where the heart does not beat properly (ventricular arrhythmias).
Source: http://www.cdc.gov/tobacco/data_statistics/fact_sheets/health_effects/tobacco_related_mortality