Smoke-free laws and disparities in secondhand smoke exposure among nonsmoking adults in the United States, 1999-2014

Nicotine Tob Res. 2021 Mar 5:ntab038. doi: 10.1093/ntr/ntab038. Online ahead of print.

ABSTRACT

INTRODUCTION: Little is known about the relationship between smoke-free laws and persistent disparities in secondhand smoke (SHS) exposure among nonsmoking adults in the U.S.

METHODS: We constructed time-varying smoke-free law measures representing whether or not at least 50% of each U.S. county’s population was covered by smoke-free laws in workplaces and hospitality venues (restaurants/bars). We merged this data with restricted data on cotinine-derived SHS exposure among nonsmokers from the National Health and Nutrition Examination Survey, 1999-2014 (N=25,444). Using logistic regression, we estimated associations between smoke-free law coverage and SHS exposure among all nonsmokers, and within age strata (25-39, 40-59, 60+). We explored differential associations by gender, race/ethnicity, education, and poverty income ratio (PIR) by testing the significance of interactions terms for the full sample and within age strata.

RESULTS: In adjusted models, hospitality coverage was associated with lower odds of SHS exposure in the full sample (odds ratio/OR=0.62; 95% confidence interval/CI=0.51-0.76), and within each age group, with ORs ranging from 0.58 (ages 25-39) to 0.67 (ages 60+). Workplace coverage was associated with lower SHS exposure only among younger adults (OR=0.81; 95% CI=0.65-0.99). Within the full sample and among adults ages 40-59, hospitality laws were associated with narrowing SHS exposure differentials between males and females. Among adults ages 40-59, workplace laws were associated with narrowing exposure differentials between males and females, but worsening exposure disparities by PIR.

CONCLUSIONS: Smoke-free laws may reduce SHS exposure among adult nonsmokers, but may be insufficient to improve disparities in SHS exposure.

PMID:33690865 | DOI:10.1093/ntr/ntab038