Second-hand smoke (SHS) is increasingly recognized as a critical risk factor for tracheal, bronchial, and lung cancers (TBLC). However, the comprehensive global burden attributable to SHS remains unclear. This study aimed to assess the global, regional, and national burden and temporal trends of SHS-attributable TBLC from 1990 to 2021, and to project future patterns through 2036.

We obtained data on disability-adjusted life years (DALYs) and deaths from tracheal, bronchus, and lung cancer (TBLC) attributable to second-hand smoke (SHS) from the Global Burden of Disease (GBD) 2021 study, covering 204 countries and territories. Subsequent analyses were stratified by sex, age group, and Socio-demographic Index (SDI). To assess temporal patterns, we computed the estimated annual percentage change (EAPC). The Bayesian Age-Period-Cohort model was applied to project future burdens until 2036. Association between disease burden and SDI was evaluated using Spearman’s rank correlation, and stage-specific trends were further explored using a smoothed curve model. 

In 2021, tracheal, bronchus, and lung cancer (TBLC) attributable to second-hand smoke (SHS) accounted for approximately 2,355,866 global DALYs—an increase of 47.3% compared to 1990. Likewise, SHS-related TBLC deaths rose to 97,911, representing a 69.9% rise over the same period. Substantial regional disparities were observed, with East Asia reporting the highest age-standardized rates of both DALYs and mortality. A moderate positive correlation was identified between TBLC burden and the Socio-demographic Index (SDI), indicating that high-SDI regions bore a heavier burden; however, these areas also demonstrated the most pronounced declines over time. Forecasts indicate that by 2036, the global age-standardized rate of DALYs and age-standardized death rate (ASDR) for TBLC attributable to second-hand smoke (SHS) will decline to 22.07 (95% CI: 14.03–30.11) and 1.00 (95% CI: 0.66–1.34) per 100,000 population, respectively.

The global burden of TBLC attributable to second-hand smoke (SHS) remains considerable, underscoring the urgent need for sustained tobacco control efforts. While projections suggest a gradual decline in both age-standardized DALY and death rates by 2036, the burden will likely persist in specific regions and populations. Strengthening policies that limit SHS exposure—particularly in indoor environments—and implementing age- and sex-sensitive strategies will be essential. High-burden areas such as East Asia should receive prioritized intervention. Ongoing surveillance and region-specific public health initiatives are critical to achieving further reductions and addressing health inequities linked to SHS exposure.