Dr. Howard Koh, former Assistant Secretary for Health at the US Department of Health and Human Services and professor at both the Harvard Chan School of Public Health and the Kennedy School, counters the popular perception that the fight against tobacco has been won, stressing that every day in the United States, thousands more teenagers pick up the habit. He discusses the new frontier opened up by e-cigarettes, recent efforts across the country to raise the smoking age to 21, and new regulations that have banned smokeless tobacco in several major league baseball stadiums.