Work

Secondhand smoke and aerosol exposure and awareness among non-smoking workers in a smoke-free workplace: A cross-sectional analysis using urinary cotinine concentrations

Year: 2026

Type: article

Abstract: INTRODUCTION: Although smoke-free workplaces have become increasingly common, residual nicotine exposure among non-smoking workers in such settings remains insufficiently characterized. This study aimed to assess secondhand smoke and aerosol (SSA) exposure and awareness of such exposure among non-smoking workers in a factory with a strict smoke-free workplace policy, using urinary cotinine as an objective biomarker of recent nicotine exposure. METHODS: As part of an occupational cohort study in Japan, a cross-sectional survey was conducted among employees of a smoke-free factory in April 2024. Participants completed a self-administered questionnaire that included items on smoking habits and SSA exposure and provided first-morning urine samples. Urinary cotinine concentrations were measured and corrected for urinary creatinine. We calculated the prevalence of self-reported SSA exposure and detectable urinary cotinine (≥0.01 ng/mL). Logistic regression was used to examine the association of age, sex, education level, marital status, occupation, shift work, chronic conditions, former smoking, and alcohol use with high urinary exposure (≥0.207 ng/mg creatinine). RESULTS: Among 746 self-reported non-current smokers, 88.5% had detectable urinary cotinine concentrations, whereas only 21.1% reported SSA exposure from combustible cigarettes or heated tobacco products (HTPs) at least once per month. Higher odds of high urinary cotinine concentrations were observed for female sex (adjusted odds ratio, AOR=1.74; 95% CI: 1.01-2.99), manual work (AOR=1.66; 95% CI: 1.06-2.60), and former smoking (AOR=1.68; 95% CI: 1.18-2.41), whereas higher level of education was associated with lower odds (AOR=0.67; 95% CI: 0.46-0.98). Among 660 participants with detectable urinary cotinine, 78.0% were unaware of their SSA exposure. CONCLUSIONS: A substantial proportion of non-smoking employees working in a smoke-free factory had detectable urinary cotinine concentrations, whereas only a minority recognized SSA exposure. Further studies are warranted to clarify exposure sources and to better characterize SSA exposure in the context of the increasing use of HTPs.

Source: Tobacco Induced Diseases

DOI: 10.18332/tid/226747