Perceptions and Use of E-cigarettes across Time among Emerging Adults.

Objectives: We present prevalence estimates of e-cigarette use and conventional cigarette use, and their co-occurrence, among emerging adults across 2 assessments, 11 months apart, conducted in 2013 and 2014. We also report on perceptions of using e-cigarettes and motives for using e-cigarettes and, among e-cigarette users, present data reflecting order of use of conventional tobacco products and e-cigarettes.

Methods: Participants (N = 884) in a longitudinal study, the Oregon Youth Substance Use Project, completed at least one of 2 questionnaires, at average age 22.9 and 23.8 years. Following each assessment, a subsample of e-cigarette users completed interviews using timeline follow-back strategies.

Results: The prevalence of e-cigarette use increased significantly across the 11 months. Compared to other nicotine products, risk perceptions associated with e-cigarettes are low. Data suggest co-occurrence between smoking conventional cigarettes and e-cigarette use, and that for most individuals, e-cigarettes are added to emerging adults' tobacco use repertoire.

Conclusions: Findings emphasize the need for common nomenclature for e-cigarettes, for counter advertising targeting emerging adults who are or were smokers, men, and those with less education. Findings also suggest that smoke-free policies designed to target conventional cigarettes incorporate e-cigarettes, as well.