How Widespread is the Use of E-Cigarettes Among Adults in the United States Who Have Never Smoked? A Tale of Three Studies

E-cigarettes are intended to be used by adults who are currently smoking combustible cigarettes as a means of quitting combustible cigarette use or substantially reducing the number of cigarettes smoked.Therefore ANS are an unintended user population. The public health impact associated with e-cigarette use by ANS depends on whether these adults are using e-cigarettes to displace combustible cigarette use (harm avoidance) or whether they would otherwise not have initiated nicotine use if e-cigarettes were not available (harm exposure).