According to an article by CDC researchers published online ahead of print in Tobacco Control, the proportion of U.S. adults who have ever used electronic cigarettes more than quadrupled from 0.6% in 2009 to 2.7% in 2010. The overall proportion of adults who had used electronic cigarettes in the past 30 days in 2010 was 1.2%.
Since the adult U.S. population in 2010 was approximately 209 million, the estimated number of current (past-month) electronic cigarette users is about 2.5 million.
The Rest of the Story
These data are important for three reasons. First, to the best of my knowledge, this is the first scientific estimate of the number of electronic cigarette users in the U.S. It helps to define the magnitude of electronic cigarette use, which is useful in public policy discussions regarding vaping and its regulation.
Second, these data demonstrate that taking electronic cigarettes off the market - as recommended by a number of anti-smoking groups - would have devastating effects on the public's health. We now know that there are literally hundreds of thousands of vapers who are using electronic cigarettes to reduce their cigarette consumption or to quit smoking entirely. Taking electronic cigarettes off the market would force most of these individuals to return to smoking, which would have devastating health effects.
Third, the fact that the number of electronic cigarette users has more than quadrupled in just one year suggests that smokers are finding these devices helpful. If they were ineffective - as suggested by some anti-smoking researchers - one would not expect the market to take off as it is.