Abstract
Background and Aims
Tobacco control policies may differentially impact smoking initiation across sociodemographic groups. We measured longitudinal associations between exposure to smoke-free laws in grade 12 (modal age 18) and patterns of smoking initiation in the U.S.
Design
Prospective longitudinal analysis.
Setting and participants
We used data on U.S. young adults sampled at modal age 18 from the Monitoring the Future Survey. Baseline data were collected between 2000 and 2017, with the last year of follow-up in 2018. The sample N varied by outcome and time point, ranging from 7,314 to 17,702.
Measurements
Smoke-free law coverage in workplaces and hospitality venues (restaurants/bars) was measured as the percent of the county population covered by each type of law. We examined associations with any past 30-day smoking initiation and daily smoking initiation at modal ages 19/20, 21/22, and 23/24, using Poisson regression and calculating average marginal effects. We explored effect modification by sex, race/ethnicity, and parental education by testing the significance of interaction terms.
Findings
Workplace law coverage at modal age 18 was associated with a lower probability of daily smoking initiation at modal ages 21/22 (-2.4 percentage points (p.p.); 95% confidence interval (CI): -3.9,-0.9) and 23/24 (-2.0 p.p.; 95% CI: -3.9,-0.2). Hospitality law coverage was associated with a lower probability of daily smoking initiation at modal ages 19/20 (-1.6 p.p.; 95% CI: -2.8,-0.4), 21/22 (-2.3 p.p.; 95% CI: -3.7,-0.9), and 23/24 (-1.8 p.p.; 95% CI: -3.6,-0.0). Findings were inconclusive with regard to associations with any past 30-day smoking initiation, and with regard to effect modification, after adjusting for multiple testing.
Conclusions
Exposure to smoke-free laws at age 18 appears to be prospectively associated with reduced daily smoking initiation 1-6 years later.