BACKGROUND: Despite substantial advancements in tobacco control and declines in smoking rates, nonsmokers continue to suffer from the adverse impacts of secondhand smoke (SHS). Timely and comprehensive estimates of the prevalence of SHS and attributable disease burden are needed to guide tobacco control. We estimated trends in the prevalence of SHS and SHS-attributable burden for 204 countries and territories, by age and sex, from 1990 to 2023.
METHODS: In the Global Burden of Diseases, Injuries, and Risk Factors Study 2023, we modeled the prevalence of exposure to SHS at home or work from 395 nationally representative surveys with data on workplace exposure, and 938 censuses and surveys with household composition information to calculate the probability of living with a smoker. We conducted systematic reviews and used the new Burden of Proof meta-analytic approach for nine outcomes causally linked to SHS. We employed a direct estimation method to calculate attributable burden.
RESULTS: ​In 2023, 2.7 billion (95% uncertainty interval 2.4-3.0) nonsmokers globally, including 766 million (687-857) children aged 0-14, were exposed to SHS, with the highest exposure rate observed in Southeast Asia, east Asia, and Oceania at 48.4% (44.0-53.4). Females experienced disproportionate exposure (37.2% [33.7-41.4]) compared to males (30.5% [27.4-34.2]), with notable regional variations. Since 1990, there has been a significant decrease in SHS prevalence among both females (26.4% reduction) and males (16.4% reduction). In 2023, SHS exposure accounted for 1.7 million (1.3-2.0) deaths and 44.7 million (35.9-55.8) disability-adjusted life years. Deaths and health loss were primarily due to ischemic heart disease among adults and lower respiratory infections among children. The largest disease burden attributable to SHS was observed in Southeast Asia, East Asia, and Oceania for females, and in Central Europe, Eastern Europe, and Central Asia for males.
CONCLUSIONS: SHS remains one of the most important risk factors for premature mortality and morbidity globally.