Are E-Cigarettes Substitutes or Complements to Combustible Cigarettes Among Youths? Evidence From Canada.

Existing evidence on whether e-cigarettes are substitutes or complements to combustible cigarettes is limited and mixed. We revisit this question using nationally-representative Canadian survey data over 14 years (2004-2017) and difference-in-differences methods that exploit the staggered adoption of e-cigarette Minimum Legal Age (MLA) laws in Canadian provinces between 2015 and 2017. We study the laws' effects not only on youth smoking but also on smoking initiation and cessation to shed light on the mechanisms through which these laws affect youth smoking. We find that the relationship between e-cigarette use and combustible cigarette use depends on smoking status of youths. While the MLA laws reduced smoking initiation among youth non-smokers, they made existing youth smokers less likely to quit smoking. Our results highlight the tradeoffs between lower smoking initiation and lower smoking cessation associated with policies that aim to reduce youth e-cigarette use.