Tracheal, bronchus, and lung cancer (TBLC) remains a major global health challenge in the 21st century, with an estimated 1.82 million deaths in 2022 (1). Asia, home to 60% of the world’s population (2), faces a particularly concerning epidemiological burden due to its rapid urbanization, industrialization, and significant demographic changes (3, 4). Limited prevention efforts, delayed diagnoses, and unequal treatment access further contribute to Asia’s lower survival rates relative to high-income nations (5, 6).

The pathogenesis of TBLC is driven by the complex interplay of lifestyle factors, genetic susceptibility, and environmental exposures. With 7 million annual deaths linked to indoor and outdoor exposure, air pollution is now recognized as the leading environmental risk factor for global disease burden and ranks second to tobacco in driving non-communicable diseases (7). Ambient particulate matter pollution (APMP), particularly fine particulate matter (PM) with an aerodynamic diameter of less than 2.5 micrometers (PM_2.5), is a key component of ambient air pollution. It is primarily sourced from vehicle emissions, industrial activities, and power generation. Given its strong association with lung cancer (8), PM_2.5 has been classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC) (9). The World Health Organization (WHO) updated its global air quality guidelines in 2021, with a recommendation that the annual mean PM_2.5 level should not exceed 5 μg/m³ (10). Similarly, household air pollution (HAP) from the burning of solid fuels—such as wood, coal, coal or charcoal—for cooking and heating represents another significant environmental risk factor for TBLC (11). This form of pollution is pervasive in many Asian households, particularly in rural and low-income settings where access to clean energy alternatives remains limited (11, 12).

Numerous previous studies have investigated the global burden of cancer attributable to air pollution, with several highlighting the particular severity in Asia. For example, the Global Burden of Disease Study (GBD) 2019 estimated that ambient PM_2.5 exposure caused approximately 7.02 million disability-adjusted life years (DALYs) globally in 2019 (13). The burden was notably higher in Asia and Africa compared to the Americas and Europe (13). However, comprehensive studies examining the combined burden of TBLC due to both APMP and HAP across 34 countries and territories in Asia remain scarce. Currently, Asia’s efforts to combat TBLC are closely linked to its air quality crisis. Yet, many countries remain resource-constrained in attaining the United Nations Sustainable Development Goals (SDGs), including SDG 3.4 (reducing premature mortality from non-communicable diseases), SDG 3.9 (lowering pollution-related morbidity and mortality), and SDG 7.1 (ensuring universal access to clean fuels) (14). This gap underscores the need for a study that integrates the latest data to assess the TBLC burden attributable to these environmental risk factors across Asia.

In this study, we conducted a secondary analysis of the most recent 2021 GBD data to quantify the burden of TBLC attributable to APMP and HAP across 34 countries and territories from 1990 to 2021. Stratified analyses were performed to assess variations by age, sex, and location. These findings offer critical insights for developing evidence-based interventions to reduce the TBLC burden caused by air pollution, thereby improving population health, and contributing to the achievement of SDGs.

The study reveals several key observations regarding the ASDR for TBLC attributed to APMP and HAP from 1990 to 2021, with stratifications by sex, age, and location. As illustrated in Table 1, the ASDR due to APMP has declined significantly in Europe and America, while in Asia, it has risen markedly. The ASDR due to HAP has decreased substantially, falling below that of APMP and reaching levels comparable to those in Africa. In Europe and America, the HAP-related ASDR has remained consistently low. Additionally, DALYs in Asia, particularly those related to APMP, have increased over the past 31 years, indicating a growing health burden. Within Asian subregions in 2021, East Asia recorded the greatest DALYs attributable to APMP, while South Asia and East Asia exhibited the highest HAP-related TBLC burden. Among the 34 Asian countries and territories examined, China reported the highest DALYs for both APMP and HAP exposures. Decomposition analysis showed that the increase in APMP-related DALYs was predominantly driven by population growth and epidemiological changes. Additionally, epidemiological changes were identified as the main drivers of the decline in HAP-related DALYs. Furthermore, ASDR were consistently higher among males, with a more pronounced sex disparities observed in ASDR attributable to APMP. Lastly, middle-aged, and older adult populations emerged as the most vulnerable demographic groups.

Research suggests that PM, particularly PM_2.5, is a significant risk factor for lung cancer, with cohort studies showing a positive association between long-term PM exposure and TBLC mortality (27–29). In high-income regions such as Europe and America, the APMP-related ASDR for TBLC has declined markedly over recent decades. Similar to the study by Deng et al. (3), the United States and the European Union exhibited a continuous decline in lung cancer-related ASDR due to total PM_2.5 exposure from 1990 to 2021, with estimated annual percentage change values of −6.01 and −2.91, respectively. This decrease is likely reflective of stringent air quality regulations, technological improvements, and robust public health interventions that have collectively reduced ambient levels of harmful PM (30, 31). Using the GEOS-Chem adjoint model, Gu et al. (32) introduced a novel method to trace the origins of PM_2.5-linked premature deaths in Europe. Their findings demonstrated that emission mitigation efforts during the first decade of PM_2.5 regulation (2005–2015) substantially decreased PM_2.5-related mortality, preventing an estimated 63,538 premature deaths (95% CI: 46,092 to 91,082) across most European countries. The implementation of policies such as the Clean Air Act in the United States and European Union directives has led to decreased emissions from industrial and transportation sources, contributing to lower exposure levels. In contrast, Asia has experienced a significant increase in APMP-related ASDR, with China shouldering the highest burden in East Asia. This upward trend in APMP-related ASDR of TBLC in Asia echoes findings from several epidemiological studies (3, 33). For instance, a spatiotemporal study from Nepal revealed that in the Kathmandu Valley, the average standardized incidence ratio (SIR) of lung cancer associated with PM_2.5 increased from a minimum of 4.96 in 2012 to a maximum of 7.81 in 2021 (29). Furthermore, a cohort study conducted in China has demonstrated a significant association between high concentrations of PM_2.5 exposure and an increased incidence and mortality rate of lung cancer (34). Vietnam’s rapid industrial development, spurred by economic growth and foreign investment, may contribute to increased APMP, potentially affecting TBLC rates (35, 36). However, specific data on air quality trends and their impact on health outcomes are necessary to confirm this. These trends reflect both the demographic transitions, including population aging and growth, and the epidemiological shifts influenced by industrial development and urbanization. Interestingly, the implementation of the Action Plan for Air Pollution Prevention and Control (2013–2017) in China resulted in a significant improvement in air quality (37, 38). The national population-weighted annual mean PM_2.5 concentration decreased from 67.4 μg/m³ in 2013 to 45.5 μg/m³ in 2017, corresponding to a 32% reduction (38). The lag effect may be at play here, as lung cancer development generally occurs over decades following exposure, meaning that current cases may reflect prior high pollution levels.

In Asia, the ASDR for TBLC due to HAP has decreased substantially, now falling below that of APMP and reaching levels comparable to those in Africa. Decomposition analysis indicates the decline in HAP-related DALYs was primarily driven by epidemiological changes, including expanded access to cleaner energy sources (e.g., liquefied petroleum gas and electricity), and improved household ventilation (39). In high-income regions (Europe and America), HAP-associated ASDR have remained persistently low, consistent with near-universal adoption of clean cooking/heating fuels (solid fuel use <5%) (40). As depicted in Table 1, the TBLC burden linked to HAP in Asia has decreased, but notable regional differences persist. The highest ASDRs attributable to HAP in 2021 were recorded in the Democratic People’s Republic of Korea, Cambodia, and the Lao People’s Democratic Republic. These countries, characterized by lower Socio-Demographic Index levels, continue to rely heavily on biomass fuels for cooking and heating, perpetuating exposure to carcinogenic pollutants. By contrast, high-income Asian countries such as South Korea, Japan, and Singapore have maintained consistently low ASDRs from HAP, with significant declines in South Korea and Singapore. These patterns may be explained by the advanced infrastructure in these countries, which enhances clean energy adoption, as well as the implementation of effective cancer control programs and advanced diagnostic and therapeutic strategies.

Our analysis revealed persistent sex-based disparities, with males exhibiting higher ASDRs for TBLC associated with both APMP and HAP compared to females in both 1990 and 2021. The male-to-female ASDR ratio was more pronounced for APMP than HAP, suggesting differential exposure pathways or biological susceptibilities. Males, in many settings, have greater exposure to outdoor air pollution, potentially due to occupational factors or increased time spent in polluted environments such as commuting or working in industrial areas. Interestingly, despite WHO reports noting that women traditionally have higher exposure to solid fuel smoke from cooking (19), males still exhibited higher ASDRs due to HAP. Anatomical and hormonal differences, including lung capacity and estrogen-mediated protective effects, may contribute to the lower susceptibility of women to air pollution-induced respiratory pathologies (41). The modest reduction in the gender gap from 1990 to 2021 could reflect changing societal roles, with more women entering the workforce and thus facing similar APMP exposure, or improvements in household ventilation reducing men’s HAP exposure. Nonetheless, it highlights the persistence of sex-based disparities that necessitate targeted policy interventions.

Across most Asia regions, individuals aged 55–69 years accounted for nearly half of TBLC DALYs attributable to APMP and HAP, reflecting the cumulative nature of air pollution exposure and the latency period of carcinogenesis. In High-income Asia Pacific, however, adults aged ≥70 years represented over 60% of DALYs in 2021. This observation may be attributable to demographic changes, including population aging and increased life expectancy. This could also indicate past high exposure levels, as older adults were exposed to worse air quality earlier in life, consistent with historical air pollution trends in high-income regions.

In conclusion, our findings highlight an urgent public health challenge in Asia: although improvements in HAP have reduced the burden of lung cancer, APMP continues to pose a significant threat. Without stricter air quality regulations and cleaner energy transitions, ongoing urbanization, and industrial growth, coupled with population growth, may increase TBLC burdens attributable to air pollution. Strengthening international cooperation and focusing on high-risk populations, particularly men, middle-aged and older adults, and low-income groups, are critical strategies to reduce the future burden of TBLC.