Introduction

Chronic obstructive pulmonary disease (COPD) is a heterogeneous lung disease characterized by progressive airflow limitation and respiratory symptoms.1–3 As the fourth leading cause of death globally, COPD accounts for 5% of all mortality.4 According to the Global Burden of Disease 2021 estimates, COPD remains a major public health concern with rising death numbers since 1990.5,6 This burden is compounded by substantial economic costs and reduced quality of life.7–9

Occupational exposures to particulate matter, gases, and fumes (PGFs) represent significant risk factors for COPD, particularly in industrializing economies. The BRICS countries (Brazil, Russia, India, China, and South Africa), characterized by rapid economic growth and industrialization, provide a crucial context for examining occupational PGFs-related COPD burden. Using the GBD 2021 database, this study will analyze the burden of COPD attributable to occupational PGFs in the five BRICS countries from 1990 to 2021, examining trends by demographic and socioeconomic factors to inform targeted public health interventions. Smoking is the primary risk factor for COPD, but non-tobacco factors, such as air pollution, occupational exposures, and poor asthma management, are also significant contributors. Research shows that non-tobacco-related COPD cases account for approximately 50% of all COPD cases globally. In low- and middle-income countries, this proportion may rise to 60–70%, due to more frequent occupational exposures and air pollution from biomass combustion (eg, wood, animal dung, straw, and coal).10–12 Compared to smoking-related COPD, individuals with non-smoking-related COPD tend to have milder chronic respiratory symptoms, less emphysema, fewer airflow limitations, and fewer comorbidities, although exacerbations remain common.10

The original Brazil, Russia, India, China, and South Africa (BRICS) countries, as emerging economies, have experienced rapid economic growth and industrialization, which has increased the risk of occupational exposures.13,14 These nations collectively bear a massive burden of COPD. For instance, they account for approximately 63.8% of global COPD prevalence and 61.3% of COPD mortality, with India and China having the highest number of prevalent cases globally. A recent study assessed the COPD disease burden in the original BRICS countries, but did not explore the impact of environmental and occupational exposures on COPD.13 The GBD 2021 dataset provides comprehensive data on morbidity, mortality, and disability-adjusted life years (DALYs) for 371 diseases and injuries, as well as 88 risk factors related to behaviors, environment, occupation, and metabolism in 204 countries.15 The strengths of this dataset lie in its use of harmonized diagnostic criteria and methods, ensuring high-quality, comparable data, and its capacity to systematically assess global and regional disease burdens.

This study addresses a critical knowledge gap by providing the first comprehensive analysis of COPD burden attributable specifically to occupational PGFs in BRICS countries from 1990 to 2021. Our work introduces four key innovations: utilizing the latest GBD 2021 data for updated estimates; conducting detailed stratification by sex, age and socioeconomic status to identify vulnerable groups; applying decomposition analysis and forecasting models to determine burden drivers and future trends; and directly linking findings to actionable public health policies tailored to the BRICS context - providing crucial evidence for targeted prevention strategies in these rapidly developing regions.

Methods Data Acquisition and Sources

This research utilized data extracted from the 2021 iteration of the GBD study, a comprehensive repository that encompasses estimates for 369 diseases and injuries, along with 88 risk factors, across 204 countries and territories spanning the years 1990 to 2021. Specifically, metrics related to COPD linked to occupational exposure to occupational PGFs—namely mortality, DALYs, years lived with disability (YLDs), and years of life lost (YLLs)—were retrieved for analysis. These datasets were accessed via the Global Health Data Exchange (GHDx) interface (http://ghdx.healthdata.org/gbd-results-tool). Additionally, the Sociodemographic Index (SDI), a composite metric reflecting national-level social and economic development (calculated from the total fertility rate, mean years of education, and lag-distributed income per capita for populations aged 15 years and above), was incorporated to evaluate the influence of socioeconomic status on disease burden. It is important to note that the SDI is distinct from other indices, such as those related to environmental sustainability, and is used here solely as a metric of socioeconomic status for comparative health burden analysis. Countries were categorized into five SDI tiers—low, low-middle, middle, high-middle, and high—based on SDI values ranging from 0 to 1. As the study is based entirely on publicly available secondary data, ethical review and informed consent were not required. All analyses were conducted in adherence to best-practice standards for transparent and accurate health data reporting.

Definitions of Key Terms

In this study, COPD is defined as a preventable and treatable disease characterized by persistent respiratory symptoms and airflow limitation, primarily caused by exposure to harmful particles or gases. The term Occupational Particulate Matter, Gases, and Fumes (OPGFs) refer to workplace exposures to airborne contaminants, including mineral dusts, chemical gases, and combustion fumes. We utilized key metrics from the GBD study: Disability-Adjusted Life Years (DALYs), which quantify the total health loss from both premature mortality (Years of Life Lost, YLLs) and time lived in states of impaired health (Years Lived with Disability, YLDs). All rates are presented as Age-Standardized Rates (ASRs), adjusted to a standard population structure to facilitate valid comparisons across populations and over time. Finally, the term “BRICS countries” refers exclusively to the original five member states: Brazil, Russia, India, China, and South Africa.

Global and Regional Burden Analysis

To explore spatial heterogeneity and regional disparities in the burden of COPD attributable to occupational PGFs, global maps were generated, and comparative regional evaluations were performed. The data were organized in accordance with the GBD regional classification framework. Visualization of the spatial distribution of COPD burden was accomplished using the R programming language (version 4.3.3), with the implementation of the ggplot2 and sf packages.

Temporal Trend Analysis

The estimated annual percentage changes (EAPCs) from 1990 to 2021 were calculated for COPD-related mortality, DALYs, YLDs, and YLLs attributed to occupational exposures, with 95% confidence intervals (CIs) computed to assess the robustness and statistical significance of observed temporal patterns.

Population Analysis

Demographic breakdowns were undertaken to delineate the burden of occupational COPD across subpopulations defined by age and sex. The analysis stratified individuals into seven age brackets (eg, 65–69, 70–74 years, etc.) for both males and females. Statistical procedures and data visualization were executed in R, employing the ggplot2 package to present the results clearly.

Decomposition Analysis

A decomposition framework was employed to disentangle the contributions of population growth, population aging, and epidemiologic transitions to changes in COPD burden, including mortality, DALYs, YLDs, and YLLs. This approach offers a nuanced understanding of the demographic and health system drivers underlying temporal changes in disease outcomes. The analytic strategy adopted aligns with methodologies previously validated in GBD research for attributing shifts in disease burden to structural population dynamics and evolving risk profiles.

Forecasting Analysis

Sex-specific projections for 2022–2050 were generated to support strategic public health planning and resource allocation, employing both Autoregressive Integrated Moving Average (ARIMA) and Exponential Smoothing (ES) models. The analysis utilized annual age-standardized rates (ASRs) of COPD burden metrics (deaths, DALYs, YLDs, YLLs) from 1990 to 2021 as the input time series. For the ARIMA modeling, optimal parameters (p,d,q) were determined through a systematic grid search, with final model selection based on the minimized Akaike Information Criterion (AIC). Concurrently, ES models were applied to capture underlying trends. Model adequacy was verified through residual diagnostics, including Ljung-Box tests for autocorrelation. The final model selection between the two approaches was based on comparative goodness-of-fit metrics, primarily the root mean square error (RMSE). The complete analytical code and detailed model specifications are provided in the Supplementary Materials to ensure full reproducibility.

Statistical Significance

This study employed a comprehensive analytical approach to assess COPD burden attributable to occupational PGFs in BRICS countries. We analyzed absolute numbers and age-standardized rates (ASRs) of key burden metrics (deaths, DALYs, YLDs, YLLs), quantifying trends through estimated annual percentage changes (EAPC). A decomposition analysis identified the drivers of burden changes over time, while both ARIMA and Exponential Smoothing models were implemented for forecasting using historical ASR data. The optimal parameters were determined through a systematic grid search and model selection based on the Akaike Information Criterion (AIC). Model adequacy was verified via residual diagnostics, including Ljung-Box tests. All statistical tests used a p-value threshold of <0.05 as the nominal significance level, with p-values considered exploratory due to multiple comparisons, consistent with established methodological practices in burden of disease research.

Results Analysis of the Current Burden and Trends of COPD Attributable to Occupational PGFs in BRICS Countries (1990–2021)

From 1990 to 2021, the number of DALYs, deaths, YLDs, and YLLs attributable to occupational PGFs-related COPD in BRICS countries showed an overall increasing trend. Among these, YLDs exhibited the most significant growth, reaching 12,601,863 (95% uncertainty interval [UI]: 10,575,240–14,969,388), followed by 585,451 deaths (95% UI: 470,475–715,711), 2,051,320 YLDs (95% UI: 1,628,637–2,459,161), and 10,550,544 YLLs (95% UI: 8,716,826–12,659,039). These figures represent increases of 30.73%, 37.70%, 122.73%, and 21.01%, respectively, compared to 1990 levels (Figure 1 and Tables 1–4).

Table 1 The DALYs Cases and Age-Standardized DALYs Rate of COPD Attributable to Occupational Exposure to Particulate Matter, Gases, and Fumes in 1990 and 2021, Along with Their Temporal Trend

Table 2 The Death Cases and Age-Standardized Death Rate of COPD Attributable to Occupational Exposure to Particulate Matter, Gases, and Fumes in 1990 and 2021, Along with Their Temporal Trend

Table 3 The YLDs Cases and Age-Standardized YLDs Rate of COPD Attributable to Occupational Exposure to Particulate Matter, Gases, and Fumes in 1990 and 2021, Along with Their Temporal Trend

Table 4 The YLLs Cases and Age-Standardized YLLs Rate of COPD Attributable to Occupational Exposure to Particulate Matter, Gases, and Fumes in 1990 and 2021, Along with Their Temporal Trend

Figure 1 The trend changes in the burden of COPD diseases attributed to occupational PGFs in BRICS countries from 1990 to 2021 ((A). DALYs; (B) Deaths; (C) YLDs; (D) YLLs).

In contrast, the corresponding age-standardized rates (ASRs) generally declined over time, except for YLDs. In 2021, the ASRs were 147.29 per 100,000 for DALYs (95% UI: 123.00–174.54), 7.03 for deaths (95% UI: 5.64–8.67), 23.79 for YLDs (95% UI: 18.87–28.51), and 123.5 for YLLs (95% UI: 101.14–147.67). The EAPCs for these indicators were −1.32 (95% UI: −1.58 to −1.05), −1.25 (95% UI: −1.59 to −0.92), 0.77 (95% UI: 0.55 to 0.99), and −1.61 (95% UI: −1.89 to −1.34), respectively (Figure 2 and Tables 1–4).

Figure 2 In 2021, the distribution of the COPD disease burden attributed to occupational PGFs among different subgroups in BRICS countries ((A). by sex; (B) by age groups; (C) by SDI regions; (D) by GBD regions).

Stratified Analysis of COPD Burden and Trends Attributable to Occupational PGFs Sex and Age

Between 1990 and 2021, both the absolute number and ASRs of COPD attributable to occupational PGFs were consistently higher in men than in women across BRICS countries. Over time, the numerical gap between men and women increased, while the gap in ASRs narrowed (Figures S1 and S2, 2A and 3A). In 1990, the male-to-female ratios for DALYs, deaths, YLDs, and YLLs were 2.07:1, 2.01:1, 1.38:1, and 2.17:1, respectively. By 2021, these ratios rose to 2.32:1, 2.38:1, 1.38:1, and 2.59:1, respectively. However, the corresponding ASR ratios declined—from 2.77:1, 3.09:1, 1.57:1, and 3.12:1 in 1990 to 2.57:1, 2.73:1, 1.63:1, and 2.70:1 in 2021 (Tables 1–4).

Figure 3 From 1990 to 2021, the trend changes in the COPD disease burden attributed to occupational PGFs among different subgroups in BRICS countries ((A) by sex; (B) by age groups; (C) by SDI regions).

The COPD burden also varied substantially by age group, displaying a unimodal distribution. The 65–69, 70–74, and 75–79 age groups bore the highest burden. In 2021, these three age groups together accounted for 50.13% of total DALYs, 47.68% of deaths, 43.09% of YLDs, and 51.49% of YLLs. ASRs increased markedly with age, reaching their peak in the 85–89 age group. In some cases, the burden in older age groups was thousands of times higher than in the youngest age group (Figure 2B and Tables 1–4). Additionally, Figure 3B shows a general decline in ASRs across most age groups between 1990 and 2021. However, this trend did not hold for older age groups (75+), which exhibited increasing trends, especially in YLDs. The number of YLDs in these groups grew the fastest, indicating that the elderly population warrants particular attention in future interventions.

SDI Regions

Over the past three decades, High SDI regions have consistently reported the lowest ASRs and absolute numbers of COPD burden attributable to occupational PGFs. In contrast, Middle SDI regions have shown the highest absolute numbers and the most rapid decline in ASRs. Notably, Low and Low-Middle SDI regions, despite having relatively low total numbers of disease burden indicators, have exhibited the second-highest ASRs in recent years, following Low-Middle SDI regions. Low-Middle SDI regions not only demonstrate the highest ASRs but also the fastest growth in burden, suggesting a critical need for public health interventions. These regions should be prioritized in health policy reform and resource allocation efforts (Figures 2C and 3C).

GBD Regions

Across the 50 GBD regions, most have experienced a decline in ASRs for occupational COPD from 1990 to 2021. The most substantial reductions were observed in Eastern Europe, East Asia, and the Western Pacific. However, a few regions—particularly the Caribbean, High-income North America, and parts of Central and Latin America—continued to exhibit increasing trends. Hierarchical clustering analysis confirmed that regions with the fastest-growing disease burden corresponded to those showing increasing ASRs (Figure 4). In 2021, substantial regional disparities in ASRs persisted. South Asia recorded the highest ASRs for all disease burden indicators, while the High-income Asia Pacific region reported the lowest. The variation was stark: up to 15-fold for DALYs, 21-fold for deaths, 7-fold for YLDs, and more than 25-fold for YLLs. In absolute numbers, Asia accounted for the majority of the global burden, with all disease indicators—DALYs, deaths, YLDs, and YLLs—making up approximately 80% of the worldwide total (Figure 3D).

Figure 4 Hierarchical clustering analysis of the COPD disease burden attributed to occupational PGFs across the 50 GBD regions globally.

Countries

To contextualize trends within the five original BRICS countries—consistent with our defined geographical scope—we conducted a comparative analysis with selected nations from the GBD database, comprising a total of 19 countries in the comparative analysis (Figures 5 and S3). This analysis revealed substantial international disparities: Belarus demonstrated the most rapid declines across all indicators, followed by Uzbekistan and China, whereas Cuba showed the steepest increases in ASRs among non-BRICS countries, with EAPCs for DALYs, deaths, and YLLs more than twice as high as those of Iran, the next fastest-growing country. Substantial inter-country variability in ASRs was observed in 2021 (Figures 6 and S4). India recorded the highest age-standardized rates across all disease burden indicators, while Belarus reported the lowest, with striking disparities reaching up to an 18-fold difference for deaths and over 14-fold for YLLs. In terms of absolute numbers, China and India accounted for the highest total burden across all metrics (Figures 7, 8 and S5, 6), reflecting their large populations and substantial industrial sectors. This comparative framework highlights the need for country-specific public health responses to occupational COPD burden.

Figure 5 Trends in age-standardized rates of COPD burden attributable to occupational PGFs across BRICS countries, 1990–2021; Age-standardized rates (per 100,000 population) are shown for (A) DALYs, (B) deaths, (C) YLLs, and (D) YLDs.

Figure 6 Age-standardized rates of COPD burden attributable to occupational PGFs in BRICS countries, 2021. Bar plots depict rates per 100,000 population for (A) DALYs, (B) deaths, (C) YLLs, and (D) YLDs.

Figure 7 Absolute counts of COPD burden attributable to occupational PGFs in BRICS countries, 1990–2021; Time trends in absolute numbers are shown for (A) DALYs, (B) deaths, (C) YLLs, and (D) YLDs.

Figure 8 Percentage change in absolute counts of COPD burden attributable to occupational PGFs in BRICS countries, 1990–2021. Percentage changes relative to 1990 values are illustrated for (A) deaths, (B) YLLs, (C) DALYs, and (D) YLDs.

Decomposition Analysis

Figures 9 and S7 clearly illustrate a significant increase in the global burden of disease attributable to occupational exposure to PGF-related COPD over the past three decades. This trend is primarily driven by population growth, particularly in low and lower-middle Socio-demographic Index (SDI) regions. At the global level, population growth contributed to increases of 507.87% in DALYs, 683.9% in deaths, 50.39% in YLDs, and 1235.2% in YLLs. Aging also contributed substantially, with respective changes of 303.48%, –294.19%, 37.81%, and –402.59%. In contrast, epidemiologic changes led to reductions of –711.36%, –289.71%, 11.8%, and –732.61% in DALYs, deaths, YLDs, and YLLs, respectively. Notably, in high-middle and middle SDI regions, the negative contribution of epidemiologic changes to DALYs, deaths, and YLLs exceeds the positive contribution from population growth. This suggests that healthcare investments in these regions may have played a significant role in mitigating the disease burden.

Figure 9 Decomposition analysis of changes in COPD burden attributable to occupational PGFs, 1990–2021. Contributions of population growth, population aging, and changes in age-specific rates to changes in (A) DALYs, (B) Deaths, (C) YLDs, and (D) YLLs.

Projections to 2050

To more accurately estimate future trends in the global burden of COPD attributable to occupational exposure to PGFs, we employed both ARIMA and ES models. Both models project continued growth in COPD burden across BRICS countries over the coming decades (Figures 10 and 11). The increase in absolute case numbers is expected to be more pronounced among women. Furthermore, the decline in age-standardized rates (ASRs) among women is projected to plateau, with some indicators possibly showing a reversal toward an upward trend. This shift in the sex burden of disease warrants continuous monitoring and timely policy interventions.

Figure 10 Projected age-standardized rates of COPD burden attributable to occupational PGFs in BRICS countries, 2022–2050. Forecasts were generated using ARIMA and exponential smoothing models for (A) deaths, (B) DALYs, (C) YLDs, and (D) YLLs. Shaded areas represent 95% prediction intervals.

Figure 11 Projected absolute number of COPD cases attributable to occupational PGFs in BRICS countries, 2022–2050. Forecasts are stratified by sex and were generated using ARIMA and exponential smoothing models for (A) deaths, (B) DALYs, (C) YLDs, and (D) YLLs.

Discussion Key Findings and Study Significance

To the best of our knowledge, this represents the first comprehensive assessment of COPD burden attributable to occupational particulate matter, gases, and fumes (PGFs) in BRICS countries using the GBD database. Our analysis reveals a general decline in age-standardized rates (ASRs) of occupational PGF-related COPD from 1990 to 2021. However, absolute case numbers continued to rise, particularly years lived with disability (YLDs), which more than doubled during this period. The burden demonstrated substantial variation across demographic and socioeconomic strata, with the greatest impact observed in older males (65–79 years) and low- and middle-income countries.

The Growing Disability Burden and Management Implications

In 2021, YLDs associated with PGFs accounted for 16.3% of total DALYs from COPD, indicating that disability represents a substantial component of the overall disease burden. The rapid increase in YLDs suggests improving COPD management in BRICS countries, where enhanced life expectancy amplifies the prominence of disabling effects. This trend necessitates a strategic shift in health policy focus—from solely saving lives toward concurrently improving quality of life. Effective management should prioritize symptom control, preservation of respiratory function, reduction of acute exacerbations, and enhancement of activity tolerance. Evidence suggests that proper inhaler techniques and interventions, such as pursed-lip breathing, can significantly improve airway patency and alveolar gas exchange, thereby reducing the severity of dyspnea.16,17

Prevention Strategies: Vaccination and Environmental Controls

Infection-triggered exacerbations account for approximately 70% of acute COPD episodes, with respiratory viruses responsible for 30% of these cases.18,19 Vaccination against influenza, SARS-CoV-2, Streptococcus pneumoniae, pertussis, respiratory syncytial virus, and varicella zoster virus represents a cornerstone strategy for exacerbation prevention. The Global Initiative for COPD accordingly recommends strengthening vaccination awareness among healthcare providers and patients.20,21 While our study could not precisely quantify PGFs’ specific impact in BRICS nations, global evidence indicates that PGFs contribute to 15.8% of the total COPD burden.22 Reducing occupational exposure to hazardous gases and dusts has demonstrated potential to lower COPD incidence and decrease disease burden by approximately 20%.23 Consequently, improving workplace environments through reduced pollutant emissions and enhanced occupational health measures, including the proper use of respiratory protection and ventilation systems, remains essential.

Evolving Disease Patterns: Sex and Socioeconomic Dimensions

Our study reveals significant variations in COPD burden across sex and socioeconomic strata. While men continue to bear a higher disease burden due to greater occupational exposure in high-risk industries and higher smoking prevalence, the sex gap has been narrowing over time. This trend reflects women’s increasing vulnerability through multiple pathways: chronic exposure to biomass fuels during household activities in developing regions, growing participation in traditionally male-dominated industries, and potentially heightened biological sensitivity to pollutants.24–28 Simultaneously, we observed a strong socioeconomic gradient in disease distribution. Since 2010, low and lower-middle-income SDI regions have experienced the highest and most rapidly increasing ASRs of COPD. Countries undergoing economic transformation, such as Belarus and China, have demonstrated declining trends through structural reforms and improved occupational protections.29,30 In contrast, nations with economic constraints like Cuba and Indonesia face persistent challenges due to continued reliance on biomass fuels and high smoking prevalence.31 These intersecting patterns highlight how sex roles and socioeconomic development jointly shape the evolving epidemiology of occupational COPD, necessitating integrated intervention approaches that address both demographic and structural determinants.

Study Limitations

The strengths of this study include the large-scale cohort, advanced modeling techniques, and accurate estimation of disease burden indicators, which contribute to a comprehensive understanding of COPD related to occupational exposure to PGFs in BRICS countries. However, several limitations must be acknowledged. First, the GBD database has inherent limitations, including variability in the quality and completeness of its underlying country-level data, which may lead to underestimation, particularly in some low- and middle-income countries. Additionally, although we employed advanced models, the analysis could not fully capture the complex interplay of socioeconomic factors, policy changes, and health behaviors. Furthermore, the numerous statistical comparisons conducted increase the risk of Type I error; as stated in the Methods, all p-values should be interpreted as exploratory without adjustment for multiple testing. Consequently, our findings are best viewed as generating robust hypotheses for future research rather than providing definitive evidence, and further validation in diverse contexts is recommended to solidify the foundation for public health policy.

Conclusion

In conclusion, despite declining age-standardized rates, the rising absolute burden of COPD attributable to occupational PGFs in BRICS countries underscores the urgent need for a comprehensive, hierarchical control strategy in high-risk workplaces. This strategy must prioritize source elimination or substitution of hazardous materials, followed by engineering controls such as process enclosure and improved ventilation. Where exposure persists, robust exposure monitoring programs and the provision of appropriate respirators are essential. The effective implementation of these measures relies on strengthened regulatory enforcement and occupational health standards. This multi-level approach is critical to reducing exposure at its source and controlling the growing burden of occupational respiratory disease.

Data Sharing Statement

The datasets and code supporting the findings of this study are available in the supplementary materials. For any additional information or specific queries regarding the data or analysis, please contact the corresponding author.

Ethics Approval and Consent to Participate

This study is a secondary analysis of data from the Global Burden of Disease (GBD) 2021 study, accessed through the Institute for Health Metrics and Evaluation (IHME) online tools. The GBD data are publicly available and provided as fully de-identified, aggregated estimates; therefore, no individual-level identifiable information was accessed or analyzed. According to the Measures for Ethical Review of Life Science and Medical Research Involving Human Subjects (China, February 18, 2023), this study qualifies for exemption from ethical review under Article 32(1) and Article 32(2) because it involves (1) legally obtained public data and (2) anonymized information only. The study does not involve any identifiable personal information or sensitive data. Specifically, Article 32(1) states that studies using “legally obtained public data” can be exempt from ethical review, and Article 32(2) allows exemption for studies using “anonymized information data”.

Funding

There is no funding to report.

Disclosure

The authors declare no competing interests.

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