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Tobacco 21 policies in California and Hawaii and sales of cigarette packs: a difference-in-differences analysis
  1. Fatma Romeh M Ali1,2,
  2. Ketra Rice1,
  3. Xin Fang3,
  4. Xin Xu1
  1. 1 Office on Smoking and Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
  2. 2 Faculty of Economics and Political Science, Department of Economics, Cairo University, Giza, Egypt
  3. 3 College of Business, Hawaii Pacific University, Honolulu, Hawaii, USA
  1. Correspondence to Dr Fatma Romeh M Ali, Office on Smoking and Health, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA; fatma_romeh{at}


Objective To measure the association of raising the minimum legal age of tobacco sales to 21 years (T21) statewide with monthly sales of cigarette packs in California and Hawaii, the first two states to implement T21 statewide.

Methods State monthly cigarette tax revenues from state departments of taxation were analysed for 11 states from January 2014 through December 2018 (n=660). Monthly cigarette packs sold were constructed using cigarette tax revenue and cigarette tax rate in each state. A difference-in-differences regression method was used to estimate the association of statewide T21 policies with monthly cigarette packs sold in California and Hawaii, separately, compared to the western states that did not implement such policies. Both models were controlled for year–month fixed effects, cigarette tax rates, smoke-free air laws, Medicaid coverage of smoking cessation, minimum legal sales ages for e-cigarettes and state marijuana laws, in addition to state demographic characteristics (sex, age, education, race/ethnicity and population size).

Findings Implementation of T21 statewide was associated with a reduction of 9.41 (95% CI=–15.52 to –3.30) million monthly packs sold in California and 0.57 (95% CI=–0.83 to –0.30) million monthly packs sold in Hawaii, compared to regional states. These translate to a reduction of 13.1%–18.2%, respectively, in monthly packs sold relative to mean values before the implementation of T21.

Conclusions Raising the minimum legal age for tobacco sales to 21 years could reduce cigarette sales as part of a comprehensive tobacco control strategy that complements and builds on proven approaches to achieve this goal.

  • addiction
  • prevention
  • nicotine
  • economics

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  • Contributors FRMA brought ideas, conducted the analysis, interpreted the results and drafted the manuscript. KR brought ideas, collected the data and contributed to the analysis and the writing of the manuscript. XF provided valuable comments and contributed to the analysis and the writing of the manuscript. XX brought ideas, supervised and revised the analysis, interpreted the results, and contributed to the writing of the manuscript. All coauthors provided substantial contributions to the design of this work and took full responsibility for it.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Disclaimer The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.