Burden of chronic respiratory diseases and their attributable risk factors in 204 countries and territories, 1990–2021: Results from the global burden of disease study 2021

Abstract

Background

Chronic respiratory diseases (CRDs) remain a substantial global public health challenge, contributing significantly to morbidity and mortality worldwide. This study aimed to comprehensively characterize trends in CRD burden across various populations by examining differences by sex, age, and sociodemographic index (SDI).

Methods

We performed a systematic analysis using data from the Global Burden of Disease (GBD) 2021 study, covering the period from 1990 to 2021 across 204 countries and territories. Estimates of age-standardized prevalence, mortality, disability-adjusted life years (DALYs), incidence, and annualized percentage changes for both 1990–2021 and 2019–2021 were calculated. Geographic and demographic variations were evaluated by age, sex, and SDI. The contributions of key risk factors—including tobacco use, ambient particulate matter (PM) pollution, household air pollution from solid fuels, and occupational exposure to PM, gases, and fumes—were also assessed.

Results

In 2021, an estimated 468.3 million individuals globally were living with CRDs, with an age-standardized prevalence rate of 5785.4 per 100,000 population. CRDs accounted for 4.4 million deaths with age-standardized mortality rate of 53.6 per 100,000 population and 108.5 million DALYs with age-standardized DALY rate of 1294.6 per 100,000 population in the same year. Age-standardized prevalence rate decreased by 1.01 % from 1990 to 2021 but increased by 0.20 % from 2019 to 2021. From 2019 to 2021, the age-standardized incidence rate of CRDs increased slightly from 713.4 to 719.3 per 100,000 population, with an annualized percentage change of 0.41 %, while the age-standardized DALY rate continued to decline from 1321.9 to 1294.6 per 100,000 population, with an annualized percentage change of −1.04 %. Although the age-standardized mortality rate declined by 1.46 % over the full period, the absolute number of deaths rose as a result of demographic shifts, including population growth and aging. Globally, tobacco use remained the predominant risk factor, while household air pollution from solid fuels was the leading contributor to DALYs and mortality in low- and low-middle SDI countries.

Conclusion

The global burden of CRDs remains both substantial and dynamic, underscoring the continued influence of risk factors such as tobacco use and household air pollution. These findings emphasize the urgent need for targeted public health interventions and more equitable healthcare resource allocation, particularly in low- and middle-SDI regions. Strengthened surveillance systems, improved access to care, and integrated strategies addressing both established and emerging risk factors are essential for reducing the global impact of CRDs.

Introduction

Chronic respiratory diseases (CRDs) encompass a diverse group of pulmonary conditions, including chronic obstructive pulmonary disease (COPD), asthma, pneumoconiosis, interstitial lung disease (ILD), and pulmonary sarcoidosis (PS). Globally, CRDs represent the fourth leading cause of mortality and account for a substantial portion of the overall disease burden, following cardiovascular diseases, respiratory infections and tuberculosis, and neoplasms.1, 2, 3 The prevalence and impact of CRDs exhibit considerable regional heterogeneity, influenced by factors such as tobacco use, air pollution, and disparities in healthcare access.⁴

A nuanced understanding of the global distribution and determinants of CRDs is critical for informing public health strategies and ensuring optimal allocation of healthcare resources. The Global Burden of Disease (GBD) studies have played a pivotal role in providing comprehensive epidemiological data that shape health policy and guide research priorities.⁵ However, ongoing shifts in global health patterns—including changes in smoking behavior, variations in pollution exposure, and demographic transitions—underscore the necessity for periodic reassessment and in-depth analyses.⁶

Earlier GBD assessments demonstrated declining age-standardized mortality and prevalence rates for CRDs from 1990 to 2019, although the absolute numbers of cases and deaths have continued to rise.² While major risk factors—such as tobacco use, ambient and household air pollution, and occupational exposures—are increasingly recognized, important knowledge gaps remain regarding their differential impact across populations.⁷ Furthermore, substantial and often unexplained disparities in CRD prevalence and outcomes across and within regions highlight the role of underlying social, economic, and health system factors.

The GBD 2021 update provides refined insights into the global CRD landscape by integrating recent epidemiological data and methodological enhancements.³ This iteration facilitates an evaluation of evolving trends in CRD incidence, prevalence, mortality, and disability-adjusted life years (DALYs), both prior to and following the COVID-19 pandemic, and underscores the persistent rise in disease burden, particularly in low- and middle-SDI settings.

The present study seeks to elucidate key demographic and geographic variations in CRD burden and associated risk exposures. These findings are essential for equipping public health authorities with the evidence required to design targeted interventions and allocate resources more efficiently. By emphasizing the ongoing and multifaceted global challenge of CRDs, this analysis underscores the urgent need for strengthened prevention strategies and improved clinical management, thereby supporting informed policy development and advancing future research aimed at mitigating the global burden of CRDs.

Methods

Data sources

This analysis utilizes data from the GBD 2021 update, which synthesizes a wide range of information from hospital and outpatient databases, civil registration systems, and population-based epidemiological studies.⁸ These data sources undergo rigorous validation and harmonization procedures to ensure standardization, thereby supporting the generation of reliable and comparable estimates. The integration of these diverse datasets enables a comprehensive assessment of global health patterns and disease burdens.⁹ CRDs —including COPD (ICD-10: J41–J44.9), pneumoconiosis (including silicosis [J62–J62.9], asbestosis [J61, J92.0], coal workers pneumoconiosis [J60], and other pneumoconiosis [J63–J63.8]), asthma (J45–J46.9), interstitial lung disease and pulmonary sarcoidosis (ILD & PS; D86–D86.2, D86.9, J84–J84.9)—were identified based on diagnostic codes from the International Classification of Diseases, 10th Revision (ICD-10).^10,11 Other chronic respiratory diseases (ICD-10: G47.3, J30–J35.9, J37–J39.9, J66–J68.9, J70, J70.8–J70.9, J82, J91, J91.8–J92, J92.9) refer to additional respiratory conditions included in the GBD 2021 study and were collectively classified under this category according to the GBD cause hierarchy.^10,11

Disease model

Building upon the GBD framework,⁶ the 2021 iteration incorporates refined data sources and advanced statistical methodologies, markedly enhancing the accuracy of disease burden estimations. Notable improvements include expanded representation of data-scarce populations and the integration of recent epidemiological datasets, thereby providing a more comprehensive depiction of the global landscape of CRDs.¹² Central to the GBD’s analytical strategy is the DisMod-MR 2.1 Bayesian meta-regression tool (Institute for Health Metrics and Evaluation [IHME], Seattle, WA, USA), which has undergone critical updates to more effectively capture non-linear associations and interactions between demographic variables and risk factors, facilitating more nuanced assessments of disease impact.¹

An important innovation in GBD 2021 is the explicit assessment of the COVID-19 pandemic’s influence on chronic disease dynamics, including CRDs. The present analysis delineates the pandemic’s effects on disease progression and management, accounting for healthcare system disruptions and shifts in environmental risk exposures.³

Risk factor analysis

This study also presents the findings of an updated risk factor analysis, quantifying the contributions of four major risk factors to the burden of CRDs: tobacco smoking, ambient particulate matter (PM) pollution, household air pollution from solid fuels, and occupational exposure to particulate matter, gases, and fumes. The analysis utilizes revised relative risk estimates and contemporary exposure data to assess the impact of these risk factors across varied environmental and socioeconomic settings. These findings are intended to inform the development of context-specific public health interventions.¹³

Statistical analysis

A descriptive analysis was performed to characterize the global, regional, and national burden of CRDs. Age-standardized rates (ASRs) for prevalence, mortality, DALYs and incidence were derived by adjusting crude rates across age groups to the GBD standard population structure.¹ This approach facilitates valid cross-population comparisons of CRD burden by accounting for differences in population age structures. Annualized percentage changes (APC) in age-standardized prevalence rate (ASPR), age-standardized mortality rate (ASMR), age-standardized DALY rate (ASDR) and age-standardized incidence rate (ASIR) were computed over the periods 1990–2021, 1990–2019, and 2019–2021.

In GBD 2021, the total percentage change for a given time period is calculated as the difference between the measure values (such as age-standardized rates) at the end point and the starting point, divided by the starting point value, and then multiplied by 100%. Because total percentage change can be calculated over different time intervals (e.g., from 1990 to 2021 or from 2019 to 2021), it is further converted into an APC to facilitate comparison across periods of varying lengths. The APC is calculated based on the principle of compound annual growth. Specifically, it represents the constant yearly growth rate that, when compounded annually over the duration of the selected time period, would result in the observed total percentage change. The uncertainty intervals (upper and lower bounds) of the APC are derived from those of the total percentage change, which in GBD are estimated using 500 or 1000 simulations, each drawing from distributions rather than point estimates. The 95% uncertainty interval is defined as the range between the 25th and 975th values after sorting the simulation results.

The extended timeframe enabled the assessment of long-term trends and the potential influence of sustained public health initiatives, while the more recent interval allowed for the identification of emerging shifts, including those potentially attributable to the COVID-19 pandemic. Results were stratified by age group, sex, sociodemographic index (SDI), region, and country. The GBD 2021 provides SDI values for 204 countries and territories, incorporating fertility, education, and income as components of a composite measure of health-related development. Stratified analyses were used to assess temporal patterns in CRDs and associated risk factors during both the pre-pandemic (1990–2019) and pandemic (2019–2021) periods. For all final estimates, 95 % uncertainty intervals (UIs) were calculated as the 2.5th and 97.5th percentile values across posterior draws—using 1000 draws for death estimates and 500 draws for prevalence, incidence, and DALYs, as defined by the GBD estimation framework. Computations per process for certain GBD 2021 estimates were reduced to 500 after simulation tests showed no impact on the final estimates or their uncertainty. All statistical analyses and graphical outputs were generated using Python software (version 3.7.10; Python Software Foundation, Beaverton, OR, USA).

Patient and public involvement

As this study was based exclusively on publicly available aggregate data, there was no involvement of patients or members of the public in the development of the research question, the determination of outcome measures, or the study design and implementation.

Results

Global trends and regional patterns by sociodemographic index

Table 1 presents the prevalent cases, deaths, DALYs, incident cases, and their corresponding ASRs with APCs across the periods 1990–2021, 1990–2019, and 2019–2021. Globally, the number of prevalent CRD cases increased from 381.2 million in 1990 to 451.8 million in 2019, further increasing to 468.3 million by 2021. Despite this rise in absolute numbers, the ASPR declined from 7936.4 per 100,000 population in 1990 to 5762.0 per 100,000 in 2019, followed by a marginal increase to 5785.4 per 100,000 in 2021. The APC in ASPR was −1.01 % from 1990 to 2021, −1.10 % from 1990 to 2019, and 0.20 % from 2019 to 2021. Across all SDI categories, the ASPR declined substantially from 1990 to 2021. The highest rates were recorded in high SDI regions (11,639.6 and 9174.2 per 100,000 in 1990 and 2021, respectively), while the lowest rates were observed in middle SDI regions (6576.0 and 5087.7 per 100,000, respectively). Over the full study period, the smallest decline in APC for prevalence was observed in low SDI regions (−0.70 %), whereas the greatest decline occurred in high-middle SDI regions (−1.03 %). Notably, during the most recent interval (2019–2021), the APC increased across all SDI levels, with the largest rise in low SDI regions (0.72 %) and the smallest in both high and high-middle SDI groups (0.11 %).

Table 1.

Prevalent cases, deaths, DALYs, incident cases, and their corresponding ASRs with APCs for CRDs at global and regional level during 1990–2021, 1990–2019 and 2019–2021.

Measure	Location	No. in millions, in 1990 (95 % UI)	ASRs per 100,000, in 1990 (95 % UI)	No., in millions, in 2019 (95 % UI)	ASRs per 100,000, in 2019 (95 % UI)	No. in millions, in 2021 (95 % UI)	ASRs per 100,000, in 2021 (95 % UI)	APC for ASRs, from 1990 to 2021 (%, 95 % UI)	APC for ASRs, from 1990 to 2019 (%, 95 % UI)	APC for ASRs, from 2019 to 2021 (%, 95 % UI)
Prevalence statistics	Global	381.2 (341.2–428.1)	7936.4 (7224.9–8809.1)	451.8 (414.1–495.1)	5762.0 (5256.6–6337.0)	468.3 (428.9–513.1)	5785.4 (5269.7–6371.9)	−1.01 (−1.10–−0.94)	−1.10 (−1.41–−0.77)	0.20 (0.02–0.37)
	High SDI	109.7 (99.7–121.0)	11639.6 (10,417.4–13,017.5)	118.7 (110.8–128.5)	9153.9 (8277.2–10,194.1)	121.0 (112.2–131.3)	9174.2 (8211.1–10,309.5)	−0.76 (−0.87–−0.62)	−0.82 (−1.17–−0.46)	0.11 (−0.55–0.80)
	High-middle SDI	72.1 (65.0–80.2)	7092.6 (6410.5–7907.6)	77.0 (70.6–85.1)	5132.0 (4588.2–5760.6)	79.4 (72.8–87.9)	5143.4 (4593.8–5798.9)	−1.03 (−1.14–−0.91)	−1.11 (−1.49–−0.71)	0.11 (−0.29–0.51)
	Middle SDI	97.0 (85.1–111.0)	6576.0 (5946.3–7357.1)	119.9 (108.7–133.1)	5068.3 (4570.1–5646.9)	124.9 (113.5–138.5)	5087.7 (4581.3–5683.2)	−0.82 (−0.91–−0.73)	−0.89 (−1.25–−0.52)	0.19 (−0.01–0.40)
	Low-middle SDI	67.8 (60.1–77.6)	6901.6 (6320.1–7620.1)	83.7 (76.1–92.4)	5304.2 (4896.0–5804.1)	87.3 (79.7–96.4)	5352.1 (4946.6–5842.9)	−0.82 (−0.91–−0.72)	−0.90 (−1.18–−0.60)	0.45 (0.15–0.75)
	Low SDI	34.0 (29.8–39.1)	7406.4 (6773.8–8128.3)	52.1 (46.1–58.7)	5873.5 (5421.2–6389.0)	55.2 (49.0–62.3)	5958.0 (5489.7–6492.7)	−0.70 (−0.78–−0.62)	−0.80 (−1.07–−0.51)	0.72 (0.32–1.07)
Mortality statistics	Global	3.0 (2.7–3.2)	84.6 (76.2–90.5)	4.3 (3.9–4.6)	54.9 (50.2–59.3)	4.4 (4.0–4.9)	53.6 (48.5–59.1)	−1.46 (−1.78–−1.01)	−1.48 (−1.79–−1.22)	−1.20 (−4.22–2.27)
	High SDI	0.4 (0.3–0.4)	32.0 (29.8–33.2)	0.6 (0.5–0.6)	24.7 (22.0–26.2)	0.6 (0.5–0.6)	24.3 (21.5–25.7)	−0.89 (−1.05–−0.77)	−0.89 (−1.28–−0.69)	−0.98 (−1.71–−0.25)
	High-middle SDI	0.7 (0.7–0.8)	86.2 (76.8–93.5)	0.7 (0.6–0.8)	39.2 (34.3–43.6)	0.7 (0.6–0.8)	38.9 (33.6–43.9)	−2.53 (−3.02–−2.04)	−2.68 (−3.13–−2.32)	−0.35 (−5.58–5.52)
	Middle SDI	1.1 (0.9–1.2)	136.8 (120.8–148.1)	1.4 (1.2–1.5)	65.3 (58.1–72.7)	1.5 (1.3–1.7)	64.3 (55.9–72.7)	−2.41 (−2.87–−1.84)	−2.52 (−2.91–−2.16)	−0.76 (−6.19–4.56)
	Low-middle SDI	0.6 (0.5–0.7)	120.6 (106.1–135.0)	1.3 (1.1–1.4)	109.9 (96.8–122.6)	1.3 (1.1–1.4)	104.9 (92.8–117.3)	−0.45 (−0.86–0.23)	−0.32 (−0.76–0.05)	−2.31 (−5.27–1.18)
	Low SDI	0.2 (0.2–0.2)	107.8 (94.5–121.8)	0.4 (0.3–0.4)	95.9 (83.7–109.9)	0.4 (0.3–0.4)	91.4 (79.7–105.1)	−0.53 (−0.92–0.06)	−0.40 (−0.87–0.06)	−2.36 (−5.35–0.80)
DALYs statistics	Global	84.9 (76.9–92.3)	2075.2 (1894.0–2237.6)	105.9 (98.0–114.2)	1321.9 (1221.2–1429.5)	108.5 (100.4–118.0)	1294.6 (1196.6–1412.1)	−1.51 (−1.75–−1.13)	−1.54 (−1.81–−1.28)	−1.04 (−3.28–1.56)
	High SDI	11.7 (10.4–13.2)	1127.8 (989.1–1307.1)	14.8 (13.6–16.3)	863.6 (758.6–1005.6)	15.1 (13.8–16.7)	853.5 (749.5–1000.5)	−0.89 (−0.98–−0.80)	−0.92 (−1.36–−0.39)	−0.58 (−1.08–−0.09)
	High-middle SDI	17.9 (16.2–19.6)	1882.1 (1707.9–2053.1)	15.6 (14.0–17.4)	886.6 (792.5–987.2)	16.1 (14.5–17.9)	879.6 (790.2–983.3)	−2.42 (−2.78–−2.04)	−2.56 (−2.94–−2.20)	−0.40 (−4.23–3.96)
	Middle SDI	28.6 (25.7–31.4)	2835.7 (2550.1–3088.9)	32.2 (29.3–35.5)	1378.8 (1249.9–1517.0)	33.6 (30.6–37.3)	1358.2 (1226.9–1507.9)	−2.35 (−2.73–−1.85)	−2.46 (−2.79–−2.13)	−0.75 (−4.95–3.46)
	Low-middle SDI	19.1 (16.9–21.1)	2883.6 (2576.1–3175.4)	31.6 (28.8–34.5)	2380.5 (2160.2–2602.8)	31.7 (28.8–34.9)	2282.6 (2071.8–2516.3)	−0.75 (−1.11–−0.17)	−0.66 (−0.99–−0.35)	−2.08 (−4.80–1.01)
	Low SDI	7.5 (6.5–8.4)	2696.6 (2393.7–3004.2)	11.6 (10.3–13.3)	2189.5 (1955.9–2476.5)	11.8 (10.5–13.6)	2111.8 (1884.7–2399.4)	−0.79 (−1.14–−0.27)	−0.72 (−1.10–−0.29)	−1.79 (−4.27–0.86)
Incidence statistics	Global	49.8 (42.8–60.3)	944.2 (823.9–1120.0)	53.8 (47.3–63.2)	713.4 (621.4–847.1)	55.2 (48.7–64.6)	719.3 (627.5–854.1)	−0.87 (−0.94–−0.80)	−0.96 (−1.43–−0.37)	0.41 (0.21–0.62)
	High SDI	9.7 (8.6–11.3)	1183.6 (1011.9–1424.7)	10.7 (9.6–12.2)	1068.4 (909.8–1285.6)	10.9 (9.8–12.4)	1075.7 (906.3–1310.7)	−0.31 (−0.40–−0.20)	−0.35 (−0.90–0.29)	0.34 (−0.74–1.27)
	High-middle SDI	8.2 (7.2–9.6)	817.8 (716.8–964.7)	7.8 (7.0–9.0)	622.6 (533.1–756.3)	8.0 (7.1–9.2)	624.4 (533.2–756.6)	−0.87 (−1.00–−0.73)	−0.94 (−1.46–−0.27)	0.14 (−0.27–0.52)
	Middle SDI	15.0 (12.6–18.4)	915.8 (797.6–1093.5)	15.1 (13.2–17.8)	677.4 (584.2–810.5)	15.5 (13.6–18.2)	681.2 (588.1–814.3)	−0.95 (−1.04–−0.86)	−1.03 (−1.54–−0.42)	0.28 (0.02–0.52)
	Low-middle SDI	10.9 (9.1–13.7)	926.8 (811.9–1094.7)	11.3 (9.8–13.4)	670.5 (597.0–776.3)	11.7 (10.2–13.7)	676.2 (602.9–783.7)	−1.01 (−1.13−−0.89)	−1.11 (−1.50–−0.61)	0.42 (0.10–0.81)
	Low SDI	5.9 (4.9–7.2)	992.5 (871.2–1169.6)	8.7 (7.3–10.6)	784.5 (690.6–913.3)	9.2 (7.6–11.2)	794.9 (700.4–929.6)	−0.71 (−0.80–−0.61)	−0.81 (−1.24–−0.29)	0.66 (0.14–1.13)

APC: Annualized percentage changes; ASRs: Age-standardized rates; CRDs: Chronic respiratory diseases; DALY: Disability-adjusted life years; SDI: Sociodemographic index; UI: Uncertainty interval.

At the global level, CRD-related deaths increased from 3.0 million in 1990 to 4.3 million in 2019, reaching 4.4 million in 2021. However, the ASMR declined markedly from 84.6 per 100,000 population in 1990 to 54.9 per 100,000 in 2019, and further to 53.6 per 100,000 in 2021. The corresponding APCs in ASMR were −1.46 % over 1990–2021, −1.48 % over 1990–2019, and −1.20 % over 2019–2021. In 1990, middle SDI group exhibited the highest ASMR (136.8 per 100,000), while the high SDI group had the lowest (32.0 per 100,000). By 2021, the highest ASMR was observed in the low-middle SDI group (104.9 per 100,000), and the lowest remained in the high SDI group (24.3 per 100,000). Across all three time intervals, APCs for ASMR were negative across all SDI groups. From 1990 to 2021, the most pronounced decline in mortality occurred in the high-middle SDI group (−2.53 %), whereas the smallest decline was seen in the low-middle SDI group (−0.45 %). Between 2019 and 2021, the lowest APC was in the low SDI group (−2.36 %) and the highest in the high-middle SDI group (−0.35 %) (Table 1).

At the global level, CRD-related DALYs increased from 84.9 million in 1990 to 105.9 million in 2019, reaching 108.5 million in 2021. From 1990 to 2021, the global ASDR attributable to CRDs declined markedly, decreasing from 2075.2 per 100,000 population in 1990 to 1321.9 in 2019, and further to 1294.6 in 2021. This corresponds to an average APC of −1.51 % over the entire period, with more pronounced reductions observed from 1990 to 2019 (−1.54 %) than from 2019 to 2021 (−1.04 %). Across all SDI quintiles, significant declines in ASDR were observed over the study period. In 1990, the highest DALY burden was concentrated in the low-middle SDI group (2883.6 per 100,000 population), whereas the high SDI group exhibited the lowest burden (1127.8 per 100,000). By 2021, this pattern persisted, with the low-middle SDI group still experiencing the highest ASDR (2282.6 per 100,000), and the high SDI group maintaining the lowest (853.5 per 100,000). Regarding temporal trends by SDI, from 1990 to 2021, the highest APC in ASDR was noted in the low-middle SDI group (−0.75 %), while the most substantial decline was observed in the high-middle SDI group (−2.42 %). Between 2019 and 2021, the APC shifted, with the low-middle SDI group showing the greatest decrease (−2.08 %) and the high-middle SDI group exhibiting the smallest decline (−0.40 %) (Table 1). The estimated number of new CRD cases in 2021 reached 55.2 million, corresponding to an ASIR of 719.3 per 100,000 population. The APC for incidence was −0.87 % from 1990 to 2021; however, this trend reversed between 2019 and 2021, showing an increase of 0.41 % (Table 1).

Supplementary Table 1 shows country-level variation in the ASPRs of CRDs in 2021, with the highest values observed in the United States, Haiti, and the United Kingdom, and the lowest in Republic of Cabo Verde. Supplementary Table 1 also shows national APCs for CRD-related ASPR from 1990 to 2021, revealing substantial inter-country variability. Japan, New Zealand, and Singapore recorded the most pronounced decreases, while Saudi Arabia, Oman, and the Syrian Arab Republic showed the steepest increases. Supplementary Table 2 shows the national CRD-related ASMRs in 2021, with Papua New Guinea, Nepal, and Myanmar reporting the highest ASMRs, and Kuwait, Montenegro, and Estonia reporting the lowest. Supplementary Table 2 also shows the national APCs in ASMR from 1990 to 2021, with the most significant reductions noted in Belarus, Singapore, and Ukraine, and the greatest increases observed in Norway, Belize, and Cuba. Supplementary Table 3 shows the national ASDRs related to CRDs in 2021, with the highest burdens reported in Papua New Guinea, Nepal, and India, and the lowest in Estonia, Singapore, and Montenegro. Corresponding APCs from 1990 to 2021 (Supplementary Table 3) show the steepest declines in Singapore, Belarus, and Ukraine, and the largest increases in Lesotho, Zimbabwe, and Belize. Supplementary Table 4 shows the national ASIRs in 2021 and APCs related to CRDs.

Finally, Fig. 1 summarizes the global number of prevalent CRD cases (in thousands) and the prevalence per 100,000 population in 2021, stratified by age and sex. Prevalent cases were highest among individuals aged 0–15 and 60–75 years, and lowest among those aged 20–30 and 85 years and older. Among individuals aged 20 and older, men consistently demonstrated lower prevalence than women, while this pattern was reversed in populations under the age of 20.

Fig. 1.

Global prevalent cases (in thousands) and global prevalence per 100,000 population of CRDs, by age and sex in 2021. CRDs: Chronic respiratory diseases; UI: Uncertainty interval.

Risk factors

Table 2 presents the major risk factors contributing to CRD-related ASDRs and ASMRs, along with the corresponding APC across three distinct time intervals: 1990–2021, 1990–2019, and 2019–2021. The primary global risk factors include smoking, ambient PM pollution, household air pollution from solid fuels, and occupational exposure to PM, gases, and fumes. Between 1990 and 2021, the global burden of CRD-related ASDRs attributable to all risk factors combined declined from 1386.5 to 775.0 per 100,000 population, representing an annual reduction of −1.86 %. In 2021, smoking remained the predominant contributor to global DALY burden, accounting for 341.7 per 100,000, with an APC of −2.11 %. This was followed by ambient PM pollution (208.3 per 100,000; APC: −0.12 %) and household air pollution from solid fuels (181.2 per 100,000; APC: −4.09 %). Occupational exposure to PM, gases, and fumes contributed the least to the global DALY burden, with a rate of 148.7 per 100,000 and an APC of −1.71 %.

Table 2.

Main risk factors for age standardised CRDs related DALYs and deaths, and APC, during 1990–2021, 1990–2019 and 2019–2021.

Measure	Risk factors by SDI	ASRs per 100,000, in 1990 (95 % UI)	ASRs per 100,000, in 2019 (95 % UI)	ASRs per 100,000, in 2021 (95 % UI)	APC for ASRs from 1990 to 2021 (%, 95 % UI)	APC for ASRs from 1990 to 2019 (%, 95 % UI)	APC for ASRs from 2019 to 2021 (%, 95 % UI)
DALYs statistics	All risk factors
	Global	1386.5 (1243.7–1526.3)	791.3 (704.6–874.9)	775.0 (689.4–861.4)	−1.86 (−2.16–−1.47)	−1.92 (−2.31–−1.58)	−1.03 (−3.90–2.16)
	High SDI	578.1 (492.4–680.7)	376.8 (317.2–443.2)	371.0 (312.0–436.7)	−1.42 (−1.57–−1.27)	−1.46 (−2.05–−0.91)	−0.77 (−1.44–−0.11)
	High-middle SDI	1356.2 (1205.9–1504.9)	540.1 (462.1–617.0)	537.5 (465.7–615.8)	−2.94 (−3.40–−2.46)	−3.13 (−3.64–−2.68)	−0.24 (−5.32–5.60)
	Middle SDI	2153.0 (1896.7–2377.2)	869.6 (752.5–987.5)	857.7 (750.0–990.3)	−2.93 (−3.41–−2.41)	−3.08 (−3.56–−2.65)	−0.69 (−5.90–4.87)
	Low-middle SDI	1900.6 (1620.6–2158.2)	1590.0 (1415.1–1755.1)	1526.3 (1355.6–1711.6)	−0.70 (−1.13–−0.11)	−0.61 (−1.01–−0.27)	−2.02 (−5.01–1.36)
	Low SDI	1637.5 (1392.7–1891.0)	1413.4 (1237.8–1565.8)	1364.7 (1217.6–1534.2)	−0.59 (−0.97–−0.05)	−0.51 (−0.96–−0.15)	−1.74 (−4.60–1.21)
	Smoking
	Global	661.2 (520.6–795.7)	351.8 (270.3–430.7)	341.7 (261.8–413.1)	−2.11 (−2.51–−1.75)	−2.15 (−3.04–−1.47)	−1.45 (−5.50–2.97)
	High SDI	341.1 (246.9–433.3)	212.5 (154.3–270.0)	206.4 (150.3–261.6)	−1.61 (−1.74–−1.48)	−1.62 (−2.70–−0.80)	−1.45 (−2.20–−0.71)
	High-middle SDI	689.9 (558.7–826.7)	293.4 (229.0–356.2)	289.8 (225.2–353.8)	−2.76 (−3.33–−2.26)	−2.91 (−3.73–−2.25)	−0.62 (−7.23–7.33)
	Middle SDI	987.3 (800.3–1177.6)	402.3 (311.3–498.0)	392.5 (298.1–480.9)	−2.93 (−3.60–−2.35)	−3.05 (−3.90–−2.33)	−1.22 (−8.95–6.94)
	Low-middle SDI	833.5 (619.8–1054.4)	605.2 (464.2–757.1)	576.5 (443.2–717.6)	−1.18 (−1.63–−0.63)	−1.10 (−2.00–−0.33)	−2.40 (−6.27–1.47)
	Low SDI	529.7 (388.6–698.5)	379.6 (280.8–482.9)	360.5 (262.4–465.6)	−1.23 (−1.69–−0.66)	−1.14 (−2.16–−0.32)	−2.55 (−6.62–1.51)
	PM
	Global	216.3 (145.0–312.4)	210.9 (154.1–257.6)	208.3 (149.6–256.6)	−0.12 (−1.17–0.86)	−0.09 (−1.16–0.61)	−0.63 (−4.25–3.53)
	High SDI	94.6 (63.0–134.1)	41.3 (29.4–54.2)	41.2 (28.9–53.9)	−2.65 (−3.69–−1.54)	−2.82 (−3.95–−1.90)	−0.18 (−2.05–2.06)
	High-middle SDI	267.6 (169.0–410.2)	175.4 (137.7–215.6)	176.2 (137.4–217.3)	−1.34 (−2.65–−0.05)	−1.45 (−2.27–−0.74)	0.23 (−5.40–6.64)
	Middle SDI	320.1 (191.9–510.8)	306.1 (219.3–373.3)	303.2 (215.1–370.4)	−0.18 (−1.61–1.33)	−0.15 (−1.30–0.53)	−0.48 (−5.78–5.08)
	Low-middle SDI	230.4 (136.1–355.4)	379.6 (216.8–517.4)	364.1 (214.0–503.4)	1.49 (0.13–2.85)	1.74 (−0.21–2.83)	−2.05 (−5.22–1.40)
	Low SDI	184.9 (110.7–280.3)	225.3 (145.1–314.9)	217.1 (141.8–306.1)	0.52 (−0.78–1.89)	0.68 (−0.83–1.85)	−1.84 (−5.44–2.05)
	HAP
	Global	661.2 (529.0–790.1)	186.7 (116.1–300.9)	181.2 (111.1–296.9)	−4.09 (−5.31–−2.78)	−4.27 (−5.82–−2.68)	−1.49 (−4.05–1.48)
	High SDI	17.6 (6.3–37.1)	0.1 (0.0–1.3)	0.1 (0.0–1.2)	−14.36 (−29.48–−10.53)	−15.29 (−33.13–−8.67)	0.21 (−3.38–2.44)
	High-middle SDI	561.0 (404.9–712.4)	13.4 (0.6–79.5)	13.6 (0.5–81.6)	−11.31 (−19.39–−6.59)	−12.08 (−21.16–−6.52)	0.64 (−6.37–7.80)
	Middle SDI	1242.7 (994.4–1468.0)	114.2 (23.0–313.5)	112.9 (23.4–316.4)	−7.45 (−11.88–−4.48)	−7.90 (−12.86–−4.64)	−0.57 (−6.07–4.93)
	Low-middle SDI	1149.4 (894.8–1407.1)	693.0 (451.4–960.8)	666.1 (431.9–935.8)	−1.74 (−2.89–−0.73)	−1.73 (−3.17–−0.62)	−1.96 (−4.84–1.48)
	Low SDI	1021.7 (797.4–1252.8)	832.9 (672.3–992.6)	804.6 (647.2–963.1)	−0.77 (−1.32–−0.08)	−0.70 (−1.43–−0.10)	−1.71 (−4.58–1.28)
	OPM
	Global	253.8 (216.2–294.1)	151.7 (126.5–177.8)	148.7 (124.2–176.0)	−1.71 (−2.10–−1.31)	−1.76 (−2.37–−1.22)	−0.99 (−4.43–2.95)
	High SDI	67.0 (56.1–78.5)	46.7 (38.8–55.0)	45.9 (38.1–54.2)	−1.21 (−1.36–−1.07)	−1.23 (−1.87–−0.67)	−0.88 (−1.83–0.05)
	High-middle SDI	251.7 (214.1–296.7)	109.9 (89.0–133.3)	109.6 (88.5–132.7)	−2.65 (−3.23–−2.09)	−2.82 (−3.52–−2.17)	−0.17 (−6.03–6.60)
	Middle SDI	448.3 (374.8–525.9)	190.1 (154.8–228.6)	186.9 (152.8–224.9)	−2.78 (−3.36–−2.21)	−2.91 (−3.60–−2.30)	−0.85 (−6.70–5.50)
	Low-middle SDI	323.7 (247.8–397.4)	290.8 (245.0–344.1)	279.9 (234.7–335.9)	−0.47 (−0.92–0.16)	−0.37 (−0.96–0.21)	−1.90 (−5.42–1.91)
	Low SDI	283.9 (219.0–346.2)	249.2 (203.6–300.0)	240.4 (197.6–287.4)	−0.54 (−0.96–−0)	−0.45 (−1.14–0.19)	−1.79 (−5.01–1.70)
Mortality statistics	All risk factors
	Global	63.9 (56.7–69.9)	36.6 (32.0–40.8)	35.8 (31.4–40.5)	−1.85 (−2.20–−1.38)	−1.90 (−2.36–−1.53)	−1.06 (−4.63–2.88)
	High SDI	19.8 (17.3–21.9)	12.3 (10.4–13.9)	12.0 (10.2–13.6)	−1.62 (−1.82–−1.43)	−1.65 (−2.21–−1.23)	−1.12 (−2.16–−0.04)
	High-middle SDI	68.5 (60.5–75.8)	26.9 (22.9–31.0)	26.8 (22.3–31.3)	−2.98 (−3.55–−2.42)	−3.17 (−3.71–−2.69)	−0.10 (−6.19–6.95)
	Middle SDI	112.3 (97.5–123.2)	45.5 (38.6–52.2)	45.0 (38.1–52.7)	−2.91 (−3.46–−2.32)	−3.07 (−3.61–−2.61)	−0.59 (−6.74–5.67)
	Low-middle SDI	87.1 (72.8–100.6)	78.0 (68.3–86.6)	74.7 (65.6–84.7)	−0.49 (−0.97–0.16)	−0.38 (−0.83–−0.02)	−2.13 (−5.20–1.41)
	Low SDI	73.8 (61.6–86.8)	67.9 (59.4–75.7)	64.9 (56.6–73.5)	−0.41 (−0.84–0.21)	−0.29 (−0.75–0.09)	−2.23 (−5.49–1.06)
	Smoking
	Global	30.9 (24.7–36.8)	17.0 (13.3–20.7)	16.5 (12.7–20.1)	−2.00 (−2.48–−1.57)	−2.05 (−2.86–−1.38)	−1.28 (−6.13–3.90)
	High SDI	12.8 (10.1–15.4)	7.7 (5.9–9.6)	7.5 (5.7–9.3)	−1.70 (−1.91–−1.53)	−1.72 (−2.63–−0.98)	−1.42 (−2.57–−0.26)
	High-middle SDI	34.7 (27.7–41.3)	15.0 (11.7–18.3)	14.9 (11.3–18.3)	−2.69 (−3.34–−2.10)	−2.85 (−3.69–−2.19)	−0.34 (−8.14–8.77)
	Middle SDI	51.4 (41.6–60.9)	21.9 (16.6–27.1)	21.4 (16.2–26.4)	−2.79 (−3.54–−2.17)	−2.91 (−3.82–−2.19)	−1.02 (−9.50–7.93)
	Low-middle SDI	39.0 (29.2–50.0)	30.2 (23.2–37.8)	28.8 (22.2–36.0)	−0.98 (−1.46–−0.32)	−0.88 (−1.77–−0.11)	−2.40 (−6.46–1.50)
	Low SDI	25.0 (18.3–33.0)	19.0 (14.1–24.1)	17.9 (13.0–23.0)	−1.07 (−1.59–−0.40)	−0.93 (−1.96–−0.12)	−3.02 (−7.31−1.22)
	PM
	Global	10.5 (7.0–15.3)	10.3 (7.6–12.7)	10.2 (7.4–12.6)	−0.09 (−1.19–0.98)	−0.07 (−1.14–0.65)	−0.49 (−4.83–4.30)
	High SDI	4.2 (2.8–6.0)	1.7 (1.2–2.3)	1.7 (1.2–2.3)	−2.88 (−3.97–−1.70)	−3.06 (−4.23–−2.13)	−0.16 (−3.02–2.96)
	High-middle SDI	14.0 (8.7–21.5)	9.2 (7.1–11.4)	9.3 (7.1–11.5)	−1.30 (−2.75–0.06)	−1.42 (−2.32–−0.69)	0.47 (−6.20–7.91)
	Middle SDI	16.9 (9.8–27.0)	16.3 (11.5–20.2)	16.2 (11.5–20.3)	−0.13 (−1.62–1.43)	−0.11 (−1.31–0.62)	−0.31 (−6.48–5.95)
	Low-middle SDI	10.9 (6.3–16.5)	18.9 (10.9–26.1)	18.1 (10.5–25.1)	1.65 (0.27–3.04)	1.92 (0.02–3.06)	−2.13 (−5.41–1.49)
	Low SDI	8.7 (5.1–13.3)	11.3 (7.3–15.6)	10.8 (7.0–15.3)	0.69 (−0.67–2.14)	0.89 (−0.62–2.04)	−2.21 (−5.92–1.94)
	HAP
	Global	32.0 (25.3–38.4)	8.6 (5.1–14.4)	8.3 (4.9–14.2)	−4.27 (−5.60–−2.83)	−4.44 (−6.13–−2.73)	−1.75 (−4.70–1.57)
	High SDI	0.9 (0.3–1.8)	0.0 (0.0–0.1)	0.0 (0.0–0.1)	−14.86 (−30.21–−11.00)	−15.84 (−33.83–−9.26)	0.59 (−4.42–3.91)
	High-middle SDI	30.5 (21.8–38.5)	0.7 (0.0–4.2)	0.7 (0.0–4.3)	−11.46 (−19.69–−6.61)	−12.27 (−21.57–−6.59)	1.27 (−6.89–10.44)
	Middle SDI	66.7 (52.7–79.0)	6.2 (1.2–17.5)	6.2 (1.2–17.7)	−7.39 (−11.95–−4.43)	−7.85 (−12.92–−4.52)	−0.37 (−6.79–5.98)
	Low-middle SDI	54.1 (41.7–67.1)	34.7 (22.2–49.1)	33.3 (21.8–47.2)	−1.55 (−2.75–−0.45)	−1.52 (−3.02–−0.33)	−2.02 (−5.05–1.60)
	Low SDI	47.6 (36.9–59.7)	40.8 (32.5–49.3)	39.1 (30.8–47.1)	−0.64 (−1.21–0.13)	−0.53 (−1.31–0.12)	−2.17 (−5.31–1.12)
	OPM
	Global	12.0 (10.0–14.2)	7.2 (5.7–8.7)	7.1 (5.7–8.7)	−1.69 (−2.13–−1.25)	−1.74 (−2.51–1.09)	−0.85 (−5.08–3.84)
	High SDI	2.9 (2.3–3.4)	1.9 (1.5–2.3)	1.8 (1.5–2.3)	−1.41 (−1.62–−1.21)	−1.45 (−2.24–−0.78)	−0.75 (−2.14–0.56)
	High-middle SDI	12.7 (10.4–15.2)	5.5 (4.2–7.0)	5.5 (4.1–7.1)	−2.65 (−3.37–−2.02)	−2.84 (−3.77–−2.03)	0.11 (−6.75–8.26)
	Middle SDI	23.2 (18.9–27.8)	10.0 (7.7–12.8)	9.9 (7.6–12.5)	−2.71 (−3.32–−2.08)	−2.85 (−3.72–−2.04)	−0.62 (−7.33–6.49)
	Low-middle SDI	15.0 (11.4–18.9)	14.1 (11.5–16.9)	13.6 (11.1–16.7)	−0.31 (−0.80–0.40)	−0.20 (−0.92–0.42)	−1.85 (−5.54–1.96)
	Low SDI	13.1 (10.0–16.7)	12.1 (9.6–14.9)	11.5 (9.1–14.3)	−0.41 (−0.89–0.19)	−0.29 (−1.07–0.43)	−2.19 (−5.68–1.65)

APC: Annualized percentage changes; ASRs: Age-standardized rates; CRDs: Chronic respiratory diseases; DALY: Disability-adjusted life years; GBD: Global Burden of Disease; SDI: Sociodemographic index; PM: Ambient particulate matter pollution; HAP: Household air pollution from solid fuels; OPM: Occupational particulate matter, gases, and fumes; UI: Uncertainty interval.

Marked variation in risk factor contributions was evident across SDI quintiles in 2021. In the high SDI group, smoking was the leading contributor (206.4 per 100,000), followed by occupational exposure to PM, gases, and fumes (45.9 per 100,000), ambient PM pollution (41.2 per 100,000), and household air pollution from solid fuels (0.1 per 100,000). In the high-middle SDI group, smoking (289.8 per 100,000) and ambient PM pollution (176.2 per 100,000) remained the top two contributors, with occupational exposure (109.6 per 100,000) and household air pollution from solid fuels (13.6 per 100,000) ranking third and fourth, respectively. The middle SDI group exhibited a similar profile, with smoking (392.5 per 100,000) and ambient PM pollution (303.2 per 100,000) as the leading risk factors, followed by occupational exposure (186.9 per 100,000) and household air pollution from solid fuels (112.9 per 100,000). In contrast, household air pollution from solid fuels was the dominant risk factor in the low-middle and low SDI groups, contributing 666.1 and 804.6 DALYs per 100,000, respectively. Smoking was the second most prominent contributor in these groups, with corresponding rates of 576.5 and 360.5 per 100,000. Contributions from ambient PM pollution and occupational exposure were lower but still substantial, with DALYs of 364.1 and 279.9 per 100,000 in the low-middle SDI group, and 217.1 and 240.4 per 100,000 in the low SDI group, respectively. Overall, the APCs for DALY rates were generally negative across all risk factors and SDI categories. However, exceptions were observed: during the 1990–2021 and 1990–2019 periods, ambient PM pollution showed a positive APC in the low-middle and low SDI groups. Between 2019 and 2021, increases were noted for ambient PM pollution in the high-middle SDI group (0.23 %) and for household air pollution from solid fuels in both the high SDI (0.21 %) and high-middle SDI (0.64 %) groups.

From 1990 to 2021, the global CRD-related ASMR attributable to all risk factors declined from 63.9 to 35.8 per 100,000 population, corresponding to an annual decrease of −1.85 %. In 2021, smoking was the leading global contributor to CRD-related deaths (16.5 per 100,000), followed by ambient PM pollution (10.2 per 100,000), household air pollution from solid fuels (8.3 per 100,000) and occupational exposure to PM, gases, and fumes (7.1 per 100,000).

As with DALYs, the burden of CRD-related deaths in 2021 due to specific risk factors varied across SDI groups. In the high-middle and middle SDI groups, smoking was the leading cause of CRD mortality, and ambient PM pollution was the second most significant contributor. In contrast, in the low-middle and low SDI groups, household air pollution from solid fuels was the leading risk factor, followed by smoking (Table 2). APCs for mortality were generally negative across all risk factors and SDI levels. However, ambient PM pollution exhibited a positive APC during the 1990–2021 and 1990–2019 periods in the low-middle and low SDI groups. Between 2019 and 2021, increases in deaths were again observed for ambient PM pollution in the high-middle SDI group (0.47 %), for household air pollution from solid fuels in the high (0.59 %) and high-middle SDI groups (1.27 %), and for occupational exposure in the high-middle SDI group (0.11 %). The most pronounced decline from 1990 to 2021 was observed in the APC for deaths attributable to household air pollution from solid fuels in the high and high-middle SDI groups, with annual reductions of −14.86 % and −11.46 %, respectively.

Subtypes of major CRDs

In 2021, asthma had the highest global ASPR among chronic respiratory diseases, reaching 3340.1 per 100,000 population with approximately 260.5 million cases, followed by COPD (ASPR: 2512.9 per 100,000 population; 213.4 million cases), ILD & PS (ASPR: 50.0 per 100,000 population; 4.3 million cases), and pneumoconiosis (ASPR: 4.6 per 100,000 population; 396,608 cases). Supplementary Table 5 presents the national ASPRs in 2021 for subtypes of major CRDs: COPD, pneumoconiosis, asthma, and ILD & PS. The highest ASPRs of COPD were observed in the United States of America, the United Kingdom, and Turkey, whereas the lowest rates were reported in Singapore, Cabo Verde, and Chile. The highest ASPRs of pneumoconiosis were observed in China, Democratic People's Republic of Korea, and Austria, while countries such as Ghana, Burkina Faso, and Nigeria reported minimal or near-zero ASPRs. Asthma exhibited the highest ASPRs in Haiti, United States of America and United Kingdom, in contrast to the lowest ASPRs observed in Lesotho, American Samoa, and Guam. For ILD & PS, the greatest ASPRs were noted in Peru, Japan and Chile, with the lowest ASPRs reported in the Philippines, Burkina Faso and Niger.

In 2021, COPD led in the greatest ASMR at 45.2 per 100,000 population, causing an estimated 3.7 million deaths worldwide, followed by asthma (436,193 deaths; ASMR: 5.2 per 100,000 population), ILD & PS (188,222 deaths; ASMR: 2.3 per 100,000 population), and pneumoconiosis (18,323 deaths; ASMR: 0.2 per 100,000 population). Supplementary Table 6 displays ASMRs for subtypes of CRDs. COPD ASMRs were highest in Papua New Guinea, Nepal, and India, while the lowest ASMRs occurred in Kuwait, Japan, and Montenegro. Pneumoconiosis-related ASMRs were most pronounced in Eswatini, Sao Tome and Principe and Lesotho; by contrast, several countries, including Antigua and Barbuda, Cuba and Fiji, recorded negligible mortality. Asthma-related ASMRs were highest in Papua New Guinea, Fiji, and Kiribati, and lowest in Monaco, Ukraine, and Greece. ASMRs attributable to ILD & PS were highest in Peru, Bolivia (Plurinational State of), and Mauritius, whereas the Republic of Moldova, Iran (Islamic Republic of) and the Philippines reported the lowest rates. ASMRs from other CRDs peaked in Papua New Guinea, Haiti, and Tajikistan, and were lowest in Estonia, Republic of Moldova and Greece.

In 2021, COPD also accounted for the greatest burden of DALYs, with 79.8 million DALYs globally (ASDR: 940.7 per 100,000 population), followed by asthma (21.4 million; ASDR: 264.6 per 100,000 population), ILD & PS (4.0 million; ASDR: 47.6 per 100,000 population), and pneumoconiosis (436,541; ASDR: 5.2 per 100,000 population). Supplementary Table 7 outlines the ASDR associated with these subtypes of CRDs. COPD-related ASDRs were highest in Papua New Guinea, Nepal, and India, while Singapore, Japan, and Kuwait exhibited the lowest burdens. The highest pneumoconiosis-related ASDRs were reported in Eswatini, Lesotho, and Sao Tome and Principe, consistent with high occupational or environmental exposure. Conversely, Antigua and Barbuda, Cuba, and Saint Vincent and the Grenadines had the lowest ASDRs. Asthma-related ASDRs were highest in Papua New Guinea, Fiji, and Haiti, and lowest in Armenia, China, and the Russian Federation. ILD & PS contributed the most significant ASDRs in Peru, Mauritius, and Bolivia (Plurinational State of), whereas the lowest values were seen in the Philippines, Iran (Islamic Republic of), and the Republic of Moldova. For other CRDs, ASDRs were highest in Haiti, Papua New Guinea, and Madagascar, and lowest in Estonia, Slovenia, and Lithuania.

In 2021, the incidence of asthma was highest, with 37.9 million new cases annually and ASIR at 516.7 per 100,000 population, followed by COPD (16.9 million cases; ASIR: 197.4 per 100,000 population), ILD & PS (390,267 cases; ASIR: 4.5 per 100,000 population), and pneumoconiosis (62,866 cases; ASIR: 0.7 per 100,000 population). Supplementary Table 8 reports ASIRs of subtypes of CRDs. COPD ASIRs were greatest in Nepal, Papua New Guinea, and India, whereas the lowest rates occurred in Cabo Verde, Singapore, and the Bahamas. The highest ASIRs of pneumoconiosis were observed in Kiribati, China, and the Democratic People’s Republic of Korea, while the Philippines, Cabo Verde, and Mauritania reported the lowest levels. Asthma ASIRs were greatest in Haiti, Poland, and Puerto Rico, contrasting with the lowest ASIRs observed in Lesotho, Pakistan, and Bhutan. For ILD & PS, the highest ASIRs were recorded in Peru, Bolivia (Plurinational State of) and Chile, whereas the Philippines, Cabo Verde, and Burkina Faso had the lowest ASIRs.

Discussion

This study underscores the persistent global health burden posed by CRDs, reporting over 468.3 million prevalent cases, 4.4 million deaths, and approximately 108.5 million DALYs in 2021. These results reflect a rising disease burden, particularly in the aftermath of the COVID-19 pandemic (2019–2021). Substantial disparities in CRD burden were observed across geographic, demographic, and socioeconomic strata. Furthermore, the study provides an in-depth assessment of region-specific risk factors, thereby enhancing current understanding of the determinants underlying CRD burden. Collectively, these findings offer critical insights to inform global public health strategies, guide research priorities, and shape policy initiatives aimed at reducing the CRD burden worldwide, positioning this study as an essential resource for policymakers and international health organizations.

This study contributes a nuanced appraisal of the evolving epidemiological trends of CRDs over the past three decades. The GBD 2019 Chronic Respiratory Diseases Collaborators previously identified CRDs as the third leading cause of mortality, responsible for 4.0 million deaths and 454.6 million prevalent cases globally, alongside declines in ASIR and ASMR from 1990 to 2019.² A national study from Iran reported a 48.9 % increase in CRD cases,¹⁴ highlighting the role of demographic transitions in shaping disease trends. In alignment with these earlier findings, the present study confirms long-term declines in ASPR, ASMR, ASDR and ASIR. However, it simultaneously emphasizes a paradoxical rise in absolute case numbers, indicating an expanding global CRD despite relative improvements in ASRs.

Of particular note, the short-term period from 2019 to 2021 revealed a reversal in several previously favorable trends. ASPRs increased during this interval, accompanied by higher APCs for prevalence, mortality, and DALYs compared to those from 1990 to 2019, even as ASMR and ASDR continued to decline. These patterns varied substantially by SDI level and time frame. The short-term prevalence trend was universally reversed from 2019 to 2021, with the low SDI region experiencing the greatest increase (0.72 %), contrasting with the long-term decline (−0.70 %). For deaths and DALYs, low and low-middle SDI regions showed more rapid declines in the short term (−2.36 % and −2.31 % for deaths; −1.79 % and −2.08 % for DALYs, respectively) than in the long-term, indicating meaningful progress. Conversely, high SDI regions exhibited accelerated declines in deaths (−0.98% short-term vs. −0.89% long-term) but decelerated declines in DALYs (−0.58% short-term vs. −0.89% long-term), suggesting possible stagnation or diminishing returns from existing health interventions. Consistent with previous studies,¹³ countries such as the United States and the United Kingdom exhibited high CRD prevalence (13,316.0 and 13073.7 per 100,000, respectively) and DALY rates (1327.3 and 1126.6 per 100,000). Between 1990 and 2021, the United States recorded a marginal increase in DALYs (0.18 %), while the United Kingdom achieved a moderate decline (−1.00 %), reflecting divergent trajectories despite similarly advanced healthcare systems. In China, a high prevalence (4434.9 per 100,000) co-occurred with modest reductions in DALYs (−3.52 %), deaths (−3.64 %), and prevalence (−0.84 %) over the study period. India demonstrated a substantially greater CRD burden, with ASMRs (133.3 per 100,000) and ASDR (2821.5 per 100,000) far exceeding global averages. Nonetheless, modest reductions were observed in DALYs (−0.69 %), deaths (−0.46 %), and prevalence (−0.88 %). In sub-Saharan Africa, countries such as Nigeria and Ethiopia reported high ASPR (6406.6 and 4008.0 per 100,000, respectively), yet experienced low DALY burdens (910.8 and 949.2 per 100,000) and mortality (28.0 and 33.6 per 100,000). These global and regional trends highlight the urgent need for targeted interventions in high-burden regions such as India and sub-Saharan Africa, while reinforcing the importance of sustaining and enhancing progress in high SDI settings.

Compared with 1990, the observed reductions in CRD-related prevalence and mortality rates suggest substantial global progress in disease management. In particular, China has enacted a series of comprehensive strategies over the past three decades to mitigate the burden of CRDs. Notably, the implementation of the National Air Pollution Prevention and Control Action Plan in 2013 introduced stringent emission standards, phased out small-scale coal-fired boilers, and promoted cleaner energy sources. These measures led to significant reductions in ambient air pollution, including PM2.5 levels,¹⁵ and were associated with declines in air pollution-related mortality and years of life lost between 2013 and 2017.¹⁶ Complementary occupational health reforms, such as those under the National Occupational Disease Prevention and Control Plan (2009–2015), improved the early detection and management of pneumoconiosis through enhanced health examinations and diagnostic capabilities, while the adoption of safer mining technologies reduced occupational exposure.¹⁷ Additionally, national tobacco control efforts under the Healthy China 2030 framework have contributed to decreased smoking prevalence, thereby mitigating the impact of smoking-related CRDs.¹⁸ To address diseases such as pneumoconiosis more effectively, coordinated improvements across upstream (e.g., coal demand reduction), midstream (e.g., personal protective equipment use), and downstream (e.g., healthcare coverage) levels are essential.¹⁷ Despite these advances, the 2019–2021 period marked an uptick in ASPRs across all SDI groups, a trend likely influenced in part by the COVID-19 pandemic. The virus has been linked to long-term pulmonary sequelae, including irreversible lung injury, chronic inflammation, and pulmonary fibrosis, which may contribute to the growing prevalence of CRDs.¹⁹ Furthermore, pandemic-related disruptions—such as delays in consultations, cancellations of surgical procedures, and interruptions in routine care—may have exacerbated disease progression and increased mortality among patients with CRDs.^19,20 These findings reinforce the urgency of enhancing both preventive and therapeutic strategies to address not only traditional risk factors but also emerging contributors to the global CRD burden.

Age-specific differences in CRD prevalent cases were most pronounced among individuals aged 0–15 and 60–75 years, with the lowest prevalent cases observed in the 20–30 and 85+ age groups. This distribution pattern is consistent with previous studies and reflects the interplay between age-related physiological vulnerability and the cumulative effects of environmental exposures. Variations by sex were also evident, driven by a complex interplay of biological, behavioral, and diagnostic factors. Among individuals aged under 15 or over 70, men exhibited a higher CRD prevalence rate, likely as a result of both physiological susceptibility and greater exposure to environmental hazards. In contrast, among adults aged from 15 to 65, women had higher prevalence rates—attributable in part to anatomical differences such as smaller airway calibers relative to lung size, which increase vulnerability to inhaled toxins.^21,22 Additional contributing factors among women include higher exposure to household air pollution from solid fuel use and increasing tobacco use in some regions. Elevated healthcare utilization rates among women^23,24 may also contribute to these sex-specific patterns by increasing diagnosis rates and revealing latent disease. This multifaceted interaction of biological, environmental, and sociocultural factors underscores the need for sex-sensitive research, targeted public health initiatives, and individualized clinical approaches to effectively manage CRDs across diverse populations.

Consistent with previous studies,¹⁵ the distribution of attributable risk factors for CRD-related DALYs and mortality demonstrates distinct patterns across countries and regions stratified by SDI level. In low and low-middle SDI regions, the burdens of DALYs and deaths attributable to all major risk factors were higher compared with high SDI regions. From 1990 to 2019, these regions exhibited relatively higher APCs in DALY rates, suggesting a slower pace of reduction. However, between 2019 and 2021, APCs declined more steeply, indicating a potential acceleration in progress during the most recent period. Despite these improvements, sustained efforts will be required to further mitigate the burden of CRDs in these settings—particularly through enhanced healthcare access, strengthened environmental protection policies, and expanded public health education initiatives. Conversely, high-middle SDl regions reported the greatest decline in ASDRs and ASMRs across the 1990–2021 period. These trends suggest that countries in these strata made earlier and more rapid advancements in reducing CRD burden. Maintaining this momentum will necessitate continued reinforcement of current public health strategies, as well as proactive responses to emerging health threats related to shifting lifestyle patterns and aging populations.

Compared to previous studies,^2,13 asthma remained the most prevalent CRDs globally in 2021, which is likely due to advances in diagnostic capabilities and management and better healthcare access. The increasing burden of asthma might also be compounded by environmental factors, such as exposure to allergens, which could be exacerbated by climate change and lengthening of pollen seasons, as indicated in previous studies.² In contrast, countries with limited healthcare access, such as Lesotho, American Samoa, and Guam, show lower asthma ASPRs. This disparity is likely influenced by underdiagnosis and limited healthcare resources. In COPD, the persistent high mortality and DALYs reflect ongoing challenges in low- and middle-income countries, where the disease burden is significantly shaped by risk factors such as smoking, environmental pollution, and inadequate healthcare. These findings underscore the urgent need for more intensive public health interventions in these regions, where COPD prevention and treatment are often limited. In contrast, high-income countries have seen a decline in COPD-related mortality, likely due to effective tobacco control policies, improved air quality, and better access to medical care. For ILD & PS and pneumoconiosis, while trends have remained relatively stable, there has been a slight increase in prevalence and incidence. These increases can likely be attributed to improved diagnostic capabilities and greater healthcare access, which have made it easier to identify and report cases. On the other hand, China, North Korea, and Austria continue to experience high burdens of pneumoconiosis, potentially linked to prolonged exposure to industrial pollutants in high-risk occupations.

Over the past three decades, all SDI groups experienced marked declines in ASDRs and ASMRs attributable to CRDs across all major risk factors. Among these, smoking has remained the leading global risk factor, particularly in middle and high SDI groups, consistent with previous studies.²⁵ Notably, reductions in DALYs attributable to smoking were observed across all SDI groups, largely driven by the widespread adoption of the World Health Organization (WHO) Framework Convention on Tobacco Control (FCTC) and its associated MPOWER policy package (an acronym representing six key tobacco control strategies promoted by the WHO). These frameworks include comprehensive tobacco control measures such as demand reduction strategies, advertising restrictions, graphic warning labels, and taxation policies. The United States, for example, reported the lowest smoking prevalence since 1965 in 2021, with only 11.5 % of adults identified as current smokers.²⁶ This milestone reflects decades of effective national and local tobacco control interventions, including the implementation of smoke-free laws, targeted public awareness campaigns such as Tips from Former Smokers, and increases in tobacco pricing. However, the rise in e-cigarette use during this period presents a new and evolving challenge to tobacco control efforts.²⁶ China, which remains the world’s largest tobacco producer and consumer, with an estimated 300 million smokers,²⁷ has also made notable progress in reducing smoking prevalence. Among men, smoking rates decreased from 63 % in 1996 to 50 % in 2018, while among women, prevalence declined from 7 % in 1984 to 2 % by 2002 and has remained consistently low since.²⁷ These achievements are largely attributable to national policies under the Healthy China 2030 framework¹⁸ and China’s robust implementation of the WHO MPOWER framework measures. By 2022, China had reached the highest level of achievement in monitoring tobacco use and the second-highest level in four additional MPOWER domains,²⁸ underscoring the country’s comprehensive and sustained commitment to tobacco control.

Ambient particulate matter pollution, after smoking, has emerged as the second leading global contributor to CRD-related DALYs and is increasingly recognized as a major factor exacerbating respiratory conditions.29, 30, 31 This shift reflects a growing public health concern tied to environmental degradation and emphasizes the urgency of region-specific environmental interventions. While ambient PM pollution ranked fourth in its contribution to CRD-related DALYs in 1990, by 2021 it had surpassed household air pollution from solid fuels in both DALYs and mortality burden. This transition underscores the rising importance of ambient PM pollution in driving respiratory morbidity and mortality, particularly in industrialized and rapidly urbanizing regions.^32,33 Mitigating this burden necessitates stringent air quality policies, expanded environmental monitoring systems, and effective emission control strategies aimed at improving population-level respiratory health.

Despite a global decline in its relative contribution, household air pollution from solid fuels remains the third leading risk factor for CRD-related DALYs and continues to be the primary contributor in low and low-middle SDI regions, where access to modern cooking and heating alternatives remains limited. For instance, in Nepal, where approximately 69 % of the population still relies on solid fuels, national efforts aim to replace traditional fuels with clean alternatives in households, with the goal of achieving universal clean energy access by 2030.³⁴ Expanding access to sustainable energy is critical not only for reducing CRD-related mortality but also for advancing progress toward the Sustainable Development Goals (SDGs) by 2030.³⁵ Meanwhile, ASDRs attributable to occupational exposure to PM, gases, and fumes have shown a global decline, reflecting improvements in workplace safety. Nonetheless, continued investment in occupational health infrastructure and policy enforcement remains essential to reduce toxic exposures and ensure adequate healthcare for vulnerable worker populations.

To enhance CRDs management strategies based on emerging risk factors highlighted in our study, we suggest several policy recommendations. First, regional action plans should be implemented to mitigate the impact of PM pollution, particularly in the areas in which it disproportionately causes CRDs. This could involve emission controls and incentives for clean technologies,^36,37 and an extensive air quality monitoring network capable of real-time surveillance of particulate matter concentrations.38, 39, 40 Second, reducing smoking rates is an urgent priority. Key actions include expanding smoke-free legislation,⁴¹ increasing tobacco taxes and prices,¹ and enhancing government investment in smoking cessation services,⁴² including counseling, pharmacotherapy, and alternative treatment options. Third, reducing air pollution from solid fuel use demands comprehensive strategies, focusing on promoting clean energy use,⁴³ improving stove technology and combustion efficiency,⁴⁴ strengthening regulations on solid fuel emissions,⁴⁵ and enhancing public awareness of the health risks associated with solid fuel combustion.⁴⁶ Fourth, effective management of chronic respiratory diseases should be implemented, including early and accurate diagnosis using tools like spirometry,⁴⁷ coupled with continuous monitoring through advanced technologies.⁴⁸

While this study offers valuable insights into global trends and risk factors associated with CRDs, several limitations warrant consideration. First, the analysis relies on a limited number of high-quality epidemiological data sources, which may affect the representativeness of the findings, particularly for regions with underdeveloped health information systems. The GBD framework used to generate the estimates incorporates advanced modeling techniques to extrapolate data for location–time combinations with sparse or nonexistent empirical input. Although this approach facilitates global comparisons, the reliability of estimates in data-deficient settings remains uncertain, as do the precision and interpretability of associated uncertainty intervals. Second, variability in the measurement and diagnosis of CRDs across regions and over time introduces potential inconsistency in the data. Differences in diagnostic criteria, reporting standards, and health system capacity may compromise comparability and influence observed trends. Third, although the analysis incorporated several established risk factors for CRDs, most associations were derived from observational studies rather than randomized controlled trials. As such, causality cannot be definitively established, and the possibility of residual confounding—particularly for environmental exposures such as air pollution, and to a lesser extent smoking—may influence the reported associations. Furthermore, the study did not account for genetic susceptibility or other nonquantifiable factors that may significantly affect CRD risk and progression. These unmeasured contributors could lead to an incomplete characterization of disease etiology and variability in burden across populations. Finally, the underdiagnosis of CRDs—particularly in low-resource settings where access to diagnostic tools such as spirometry is limited—may result in systematic underestimation of prevalence and disease severity. This underscores the urgent need to improve diagnostic infrastructure and promote the adoption of standardized measurement protocols in future epidemiological research to enhance the accuracy and comparability of CRD burden assessments.

This study conducted a comprehensive analysis of CRDs from 1990 to 2021, providing updated insights into the prevalence, mortality, DALYs, incidence, and major risk factors at global, regional, and national levels. A notable finding is the emergence of household air pollution from solid fuels as the leading contributor to CRD-related DALYs and deaths in low SDI regions—surpassing smoking and accounting for the majority of the disease burden in these settings. This transition reflects the evolving risk landscape and underscores the urgent need for integrated public health strategies that target both environmental determinants, such as household air pollution from solid fuels, and conventional factors, such as tobacco use. These findings carry important implications for health policy, emphasizing the necessity for dynamic and context-specific interventions. Policymakers must strengthen efforts to expand clean energy access, enforce environmental regulations, and reinforce tobacco control while improving the delivery of preventive and therapeutic services. Such multifaceted strategies are essential to alleviating the burden of CRDs and advancing the resilience and responsiveness of global health systems.

Funding

The study was supported by Ministry of Science and Technology of the People's Republic of China (No. 2023ZD0506000); State Key Laboratory Special Fund (No. 2060204); Horizon Europe (HORIZON-MSCA-2021-SE-01; Project number 101086139-PoPMeD-SuSDeV).

Author statement

The author Chen Wang is the Editor-in-Chief and Simiao Chen is an Editorial Board Member for this journal and were not involved in the editorial review or the decision to publish this article.

Data availability

All data used in this study are publicly available from the Global Burden of Disease (GBD) study. Detailed access procedures and documentation can be found at: https://www.healthdata.org/gbd.

CRediT authorship contribution statement

Zhong Cao: Writing – original draft, Methodology, Investigation, Conceptualization. Liu He: Writing – original draft. Yuheng Luo: Validation, Data curation, Writing – review & editing. Xunliang Tong: Writing – review & editing. Jinghan Zhao: Writing – review & editing. Ke Huang: Writing – review & editing. Qiushi Chen: Writing – review & editing. Lirui Jiao: Writing – review & editing. Yuhao Liu: Writing – review & editing. Pascal Geldsetzer: Writing – review & editing. Ting Yang: Writing – review & editing. Chen Wang: Writing – review & editing. Till Winfried Bärnighausen: Writing – review & editing, Funding acquisition. Simiao Chen: Writing – review & editing, Supervision, Project administration, Funding acquisition.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Edited by: Peifang Wei