It's estimated that tobacco causes about one in five (the equivalent of about 443,000) deaths each year. Of these, around 49,000 smoking related deaths are the result of exposure to secondhand smoke.
Source: Centers for Disease Control and Prevention. Smoking-Attributable Mortality, Years of Potential Life Lost, and Productivity Losses—United States, 2000–2004. Morbidity and Mortality Weekly Report 2008;57(45):1226–8. Retrieved Oct 22. 2011.
