LAUSR

AIMS To estimate whether and to what extent extending indoor smoking restrictions to include electronic cigarettes (ECs) impact the use of ECs and cigarette smoking among adults in the US. DESIGN Observational study using a linear probability model and applying a difference-in-differences analysis SETTING: USA PARTICIPANTS: People aged 18 to 54 who lived in US counties where comprehensive indoor smoking laws in bars, restaurants, and private workplaces have been in place prior to 2010 (N = 45,111 for EC use analysis, N = 75,959 for cigarette use analysis). MEASUREMENTS Data on cigarette smoking, use of ECs, and place of residence from the Tobacco Use Supplement of the Current Population Survey (TUS-CPS 2010-2011, 2014-2015, and 2018-2019) were combined with the American Nonsmokers' Rights Foundation (ANRF) database of state and local indoor smoking and vaping restriction laws. FINDINGS Indoor vaping restriction (IVR) coverage was not significantly associated with the likelihood of adult EC use (coefficient estimate = 0.001; 95% confidence interval [CI] =-0.009, 0.013, P-value = 0.783). In addition, IVR coverage was not significantly associated with adult cigarette smoking (coefficient estimate = -0.00; 95% CI = -0.016, 0.015, P-value = 0.954). The non-significant results appeared in different socio-demographic subgroups. CONCLUSIONS Indoor vaping restrictions do not appear to decrease electronic cigarette use among US adults. There is no evidence that indoor vaping restrictions increase or decrease cigarette smoking among US adults.