The Impact of Layering Tobacco 21 Laws and Smoke-Free Laws on U.S. Adolescent Smoking Behaviors

Smoke-free and Tobacco 21 laws are complementary tobacco control strategies that reduce adolescent cigarette smoking. To test for policy layering, this study examined the impact of county-level Tobacco 21 laws on adolescent smoking in counties with different smoke-free policy environments.

This study used repeated cross-sectional data from the Monitoring the Future study (2014-2020) to examine interactions between county-level Tobacco 21 coverage (<100% vs 100%) and smoke-free workplace and hospitality law coverage (<100% vs 100%) on past 30-day cigarette use, smoking initiation, and smoking intentions among 10th (ages 15-16 years) and 12th (ages 17-18 years) graders. Universal coverage was defined as 100% coverage for both Tobacco 21 and smoke-free laws. Interaction terms were estimated using grade-stratified modified Poisson regression models and interpreted as marginal effects on the basis of predicted probabilities.

Universal coverage was associated with a lower probability of cigarette smoking initiation among 10th graders (marginal effect= -0.011, 95% CI= -0.037, -0.006) than in counties with less than universal coverage for both Tobacco 21 and smoke-free workplace laws. Among 12th graders, universal coverage was associated with a lower probability of past 30-day cigarette use (workplace marginal effect= -0.035, 95% CI= -0.054, -0.016; hospitality marginal effect= -0.039, 95% CI= -0.060, -0.019) than in counties with less than universal coverage.

This study found that layering Tobacco 21 law coverage with smoke-free workplace and hospitality law coverage was associated with lower adolescent smoking. Although the patterns were not consistent among 10th and 12th graders for all smoking outcomes, the results suggest that policy layering may be an effective tobacco control strategy to reduce adolescent smoking.