Chronic respiratory diseases (CRDs) represent a substantial component of the global burden of disease, contributing significantly to morbidity, mortality, and healthcare expenditure worldwide. This review synthesizes current evidence on the epidemiology, determinants, and both population-level and individual impacts of four major respiratory health conditions: asthma, chronic obstructive pulmonary disease (COPD), interstitial lung disease (ILD), and smoking; the latter is both a disease in itself and a major contributor to respiratory and non-respiratory morbidity.
Despite distinct pathophysiological mechanisms, these conditions share common risk factors, including environmental exposures and socioeconomic determinants, which contribute to diagnostic and management challenges. This review examines the burden of these conditions at both individual and population levels, explores current and future trends, and highlights the critical need for coordinated public health strategies, primary prevention, and global policy interventions to mitigate their growing impact.
Considering the interconnections between human, animal, and environmental health, a unifying framework of planetary respiratory medicine and One Health may provide solutions to the CRD burden by promoting lung health across the life course.
Non-communicable diseases (NCDs) are the leading cause of death and disability worldwide, and chronic respiratory diseases (CRDs) are a major contributor to this burden [1]. The Global Burden of Disease (GBD) study consistently ranks CRDs among the leading causes of mortality and disability-adjusted life years (DALYs) [2].
This review focuses on four key areas: asthma, a common chronic disease affecting all age groups; COPD, a leading cause of death largely driven by smoking and air pollution; interstitial lung disease (ILD), a heterogeneous group of often severe parenchymal lung disorders; and smoking, a disease that represents the single most important preventable risk factor for respiratory and overall health. Understanding their epidemiology, shared and distinct determinants, and future challenges is essential for guiding effective healthcare responses and policy development.
AsthmaEpidemiological burdenAsthma is one of the most common chronic diseases globally, affecting an estimated 262 million people and causing more than 461,000 deaths annually [3]. Its prevalence has increased markedly over the past several decades, particularly in urbanized settings and among children. While asthma is present in every country, prevalence rates vary significantly and are generally higher in high-income countries (HICs); however, the burden of morbidity and mortality is disproportionately higher in low- and middle-income countries (LMICs) owing to inadequate access to diagnosis and essential inhaled drugs [4].
Furthermore, in New Zealand and Australia, specific short-acting β2-agonists (SABAs), such as fenoterol or isoprenaline, as well as overuse of SABAs in the United States and other countries, were historically associated with increased asthma mortality [5,6]. Asthma accounts for a substantial number of disability-adjusted life years (DALYs), primarily due to years lived with disability (YLDs), resulting from chronic symptoms, acute exacerbations, and limitations in daily activities [7].
The global distribution of asthma demonstrates marked geographic disparities in prevalence and mortality estimates (Fig. 1). Prevalence is highest in high-income English-speaking countries (e.g., the United Kingdom, Australia, New Zealand, the United States, and Canada), northwestern Europe, and parts of Latin America [8]. Multiple hypotheses—including the hygiene hypothesis, Westernization, obesity, and increased allergic sensitization—may partially explain this variability.
New Zealand has the highest prevalence, with a rate of 14,516 per 100,000 population (>14% across all age groups), followed by Costa Rica and Honduras among the top three.
In contrast, asthma mortality is disproportionately higher in LMIC regions, particularly in sub-Saharan Africa and South Asia. The highest mortality rates are reported in Sri Lanka, Fiji, and Myanmar, with 33.7, 25.4, and 21.5 deaths per 100,000 population, respectively.
However, substantial heterogeneity in the distribution of asthma determinants across small geographic areas and varying data granularity results in considerable variability in prevalence estimates, even at the neighborhood level [9].
Exposures and determinantsThe development and exacerbation of asthma are influenced by a complex interplay of genetic predisposition and environmental exposures.
Host factors: A family history of asthma or atopy (allergic conditions) is a strong risk factor [10].
Aeroallergens: Exposure to indoor allergens (e.g., house dust mites, pet dander, cockroaches, and mold) and outdoor allergens (e.g., pollen) is a major trigger for allergic asthma [11].
Air pollution: Both outdoor pollution (particulate matter [PM2.5, PM10], nitrogen dioxide [NO2] from vehicle emissions) and indoor pollution (from biomass fuel use for cooking and heating, particularly in LMICs) are significant risk factors for asthma development and exacerbation [12].
Tobacco smoke: Exposure to environmental tobacco smoke, especially in utero and during childhood, increases the risk of asthma development and worsens disease control [13].
Occupational exposures: An estimated 10–25% of adult-onset asthma is attributable to occupational exposure to irritants and sensitizers (e.g., isocyanates, flour dust, cleaning agents) [14].
Socioeconomic status: Lower socioeconomic status is associated with higher asthma prevalence and worse outcomes, mediated by factors such as poor housing conditions, increased allergen exposure, psychosocial stress, and limited access to health care [15].
A more comprehensive list of asthma risk factors is available elsewhere [16].
Challenges and future trendsA major challenge is the substantial underdiagnosis and undertreatment of asthma, particularly in LMICs [7]. Even in HICs, a subset of patients has severe asthma that remains difficult to control with standard therapies [17].
The heterogeneity of asthma necessitates a shift toward personalized medicine, including consideration of targeted biologic therapies; however, cost and access remain significant barriers [18].
Future trends are concerning. Urbanization and climate change are expected to increase exposure to air pollutants and aeroallergens, potentially driving higher prevalence rates [19]. Addressing the global asthma burden requires a multifaceted approach, including improving access to affordable essential medications worldwide, implementing policies to enhance air quality, reducing tobacco use, and integrating asthma management into primary health care systems.
Chronic obstructive pulmonary disease (COPD)Epidemiological burdenCOPD is a leading cause of mortality worldwide, responsible for an estimated 3.23 million deaths in 2023, making it the third leading cause of death globally [2]. The prevalence of COPD is substantially underestimated owing to underdiagnosis, with estimates suggesting that it affects more than 300 million people [20].
The burden of DALYs is considerable, reflecting both years of life lost due to premature mortality and years lived with disability from debilitating symptoms such as dyspnea and chronic cough. While historically more common in men in HICs, the prevalence among women is increasing globally owing to rising tobacco use and exposure to biomass fuels. The burden is increasing most rapidly in LMICs.
COPD mortality trends are highly heterogeneous and appear partly unrelated to classical determinants (Fig. 2) [21,22]. The highest prevalence and mortality rates are consistently observed in South Asia and Southeast Asia, driven by historically high smoking rates in men and substantial exposure to household and ambient air pollution, particularly among women and children. Central Europe also demonstrates a high burden, largely associated with tobacco use and occupational exposures in men. Mortality rates in these regions may be several times higher than those observed in high-income North America or western Europe.
At the extremes, high COPD mortality is observed in Denmark, Bhutan, Nepal, and Bangladesh. In Greenland, a male-to-female mortality ratio of 60.1 vs 76.5 deaths per 100,000 population has been attributed to high smoking prevalence among women (29.8%), similar to Denmark.
Exposures and determinantsCOPD is characterized by persistent respiratory symptoms and airflow limitation due to airway and/or alveolar abnormalities, usually caused by significant exposure to noxious particles or gases [23,24].
Smoking remains the single most important risk factor for COPD in most countries. Both active smoking and secondhand smoke exposure contribute to risk [25]. Emerging nicotine delivery systems—including electronic cigarettes, heat-not-burn tobacco products, and oral nicotine products such as snus or pouches [26]—may influence smoking initiation and modify health risks, although their long-term effects remain under investigation.
Household air pollution: In many LMICs, exposure to smoke from biomass fuels (e.g., wood, dung, crop residues) used for cooking and heating in poorly ventilated homes is a major cause of COPD, particularly among women [27].
Occupational exposures: Workplace dusts (organic and inorganic), chemical agents, and fumes are significant contributors to COPD risk [28].
Ambient air pollution: Long-term exposure to outdoor air pollution (PM2.5, ozone) is an established risk factor for COPD development and contributes to exacerbations [29].
Other factors: Childhood respiratory infections, a history of tuberculosis, and socioeconomic deprivation may impair lung growth and accelerate lung function decline, increasing susceptibility to COPD [30].
Alpha-1 antitrypsin deficiency is a rare genetic cause of COPD and associated liver disease; however, given its identifiable nature, it should be considered and excluded in younger patients with COPD [31].
Challenges and future trendsCOPD remains substantially underdiagnosed, often until it reaches an advanced clinical stage [32]. Stigma associated with the disease as a “self-inflicted” condition may hinder help-seeking behavior and public health efforts [33].
Management is frequently suboptimal, with overreliance on reliever rather than preventive therapies [34].
The future trajectory of COPD is concerning. Aging populations, persistently high smoking prevalence in many regions, continued use of biomass fuels, and increasing levels of ambient air pollution suggest that the global burden will continue to rise, particularly in LMICs [35].
Key strategies include comprehensive tobacco control, promotion of clean household and transportation energy sources, improvements in outdoor air quality, early detection through spirometry in primary care, and development of effective disease-modifying therapies.
Interstitial lung disease (ILD)Epidemiological burdenILDs comprise a large and heterogeneous group of more than 200 disorders characterized by inflammation and fibrosis of the lung parenchyma [36]. Accurate epidemiological data are more difficult to obtain than for asthma or COPD owing to their relative rarity and complexity.
Idiopathic pulmonary fibrosis (IPF) is the most common and likely most severe idiopathic ILD, with a reported prevalence of 13–20 per 100,000 population [37]. Other ILDs, including those associated with connective tissue diseases (e.g., rheumatoid arthritis, scleroderma) and hypersensitivity pneumonitis, also contribute substantially to morbidity and mortality. ILDs collectively impose a high burden of disability and are associated with poor quality of life for patients and their families.
ILD prevalence and mortality rates are generally highest in high-income regions, including North America and Europe (Fig. 3). This likely reflects improved diagnostic capabilities and aging populations, although incidence appears to be increasing globally. However, compared with asthma and COPD, there are currently no large international surveys assessing the global extent and determinants of ILDs, and most available data are extrapolated from a limited number of studies.
Japan is considered an outlier, with high mortality (25.8 per 100,000) and prevalence (466.1 per 100,000), followed by Peru (21.8 and 165.2 per 100,000, respectively), for reasons that remain unclear [38–40].
Exposures and determinantsThe etiologies of ILDs are diverse and often multifactorial; however, many cases remain idiopathic despite comprehensive evaluation [41].
Occupational and environmental exposures: Some ILDs result from inhalation of inorganic and organic dusts. These include pneumoconioses (e.g., asbestosis, silicosis, coal workers’ pneumoconiosis) and hypersensitivity pneumonitis (e.g., exposure to bird antigens or moldy hay) [42]. These risks persist in both traditional industries and emerging settings (e.g., silica exposure during engineered stone fabrication) [43].
Smoking: Cigarette smoking is a major risk factor for the development of IPF and respiratory bronchiolitis-associated ILD [44].
Drugs[45]and radiotherapy: Numerous drugs (e.g., chemotherapeutic agents, nitrofurantoin, amiodarone) may cause pulmonary toxicity and drug-induced ILD [46].
Connective tissue diseases (CTDs): ILD is a common and serious complication of CTDs and represents a leading cause of mortality in these populations [47].
Idiopathic factors: For many ILDs, including IPF, the cause remains unknown; however, genetic predispositions (e.g., telomerase mutations) are increasingly recognized [48].
Challenges and future trendsA major challenge is delayed diagnosis, as early symptoms are often nonspecific and access to specialized centers with multidisciplinary teams (MDTs) is limited [49].
Treatment options for fibrotic ILDs, such as IPF, remain limited and do not reverse disease progression. There is also a substantial lack of awareness among both the general population and non-specialist clinicians [50].
Future trends suggest that the burden of ILD may increase owing to improved recognition, aging populations, and emerging occupational and environmental exposures [37].
The future of ILD management depends on improving early and accurate diagnosis through MDT collaboration, developing more effective antifibrotic therapies, implementing screening strategies in high-risk populations (e.g., patients with CTDs or occupational exposures), and strengthening global registries to enhance epidemiological and clinical understanding.
SmokingEpidemiological burdenTobacco smoking is the leading preventable cause of death globally, responsible for more than 8 million deaths annually. More than 7 million deaths are attributable to direct tobacco use, whereas approximately 1.2 million result from exposure to secondhand smoke [51].
The World Health Organization (WHO) classifies tobacco dependence as a disease rather than merely a lifestyle behavior, with ICD-10 code F17 and ICD-11 code 6C4A. Recognizing smoking as a disease supports research into medical treatment, improves insurance and health care coverage, reduces stigma, enhances cessation support, and strengthens tobacco control policies.
A substantial proportion of tobacco-related deaths are due to respiratory diseases, including COPD, lung cancer, pneumonia and other respiratory infections. Tobacco smoke also exacerbates asthma and tuberculosis. Smoking-attributable morbidity places a considerable burden on health care systems.
Although smoking prevalence has declined in many HICs owing to comprehensive tobacco control policies, it remains high in many LMICs. The total number of smokers worldwide remains substantial and is projected to plateau at approximately 1.2 billion through 2050 if current trends persist [52,53].
The epidemiology of smoking shows marked variability driven by historical patterns (e.g., the four stages of the tobacco epidemic), sociodemographic factors, tobacco industry influence, and national control policies (Fig. 4). The highest prevalence of tobacco use, measured as summary exposure value (a composite metric incorporating prevalence, duration, and intensity of use) [53], is observed in Eastern Europe, with Montenegro (37.0%), Bulgaria (34.8%), and North Macedonia (34.6%) ranking highest globally.
In terms of mortality, Monaco represents an outlier, with 205.4 deaths per 100,000 population attributable to smoking, likely reflecting its small, aging population and role as a referral center for patients with advanced disease.
Exposures and determinantsSmoking is both a disease and a behavior influenced by multiple interacting factors.
Nicotine addiction: The highly addictive nature of nicotine is the primary driver of sustained tobacco use [54].
Tobacco industry influence: Marketing strategies, particularly those targeting youth and populations in LMICs, contribute significantly to smoking initiation [55].
Socioeconomic factors: Smoking prevalence is consistently higher among individuals with lower educational attainment, lower income, and increased psychosocial stress [56].
Policy environment: Weak implementation of evidence-based tobacco control measures (MPOWER) is a key determinant of high smoking prevalence [57]. MPOWER encompasses six WHO strategies: monitoring tobacco use, protecting individuals from tobacco smoke, offering cessation support, warning about the dangers of tobacco, enforcing bans on advertising and promotion, and raising tobacco taxes.
Secondhand smoke: Non-smokers, particularly children and household members, are exposed to harmful effects of tobacco smoke in homes, workplaces, and public settings [58].
Emerging evidence suggests that thirdhand smoke (residual contamination on surfaces and materials) and environmental exposure to tobacco-related toxins [59], including those derived from cigarette waste (fourth-hand smoking), may also contribute to health risks and environmental harm [60], reinforcing the need for comprehensive tobacco control and a broader planetary health perspective.
Challenges and future trendsDespite progress, challenges remain substantial. The tobacco industry continues to adapt by marketing new products, such as electronic cigarettes and heated tobacco devices, often targeting young individuals and undermining existing regulations [61]. Dual use of conventional and novel tobacco products is an increasing concern.
Equity remains a major issue, with smoking becoming progressively concentrated in vulnerable populations. Future trends suggest a shifting burden of tobacco-related disease toward LMICs. The WHO Framework Convention on Tobacco Control remains the key global instrument for progress.
Future success depends on full implementation and enforcement of cost-effective policies, including higher tobacco taxation, comprehensive smoke-free legislation, plain packaging with graphic health warnings, bans on advertising and promotion, and population-wide cessation support [51].
Interventions for impactBeyond the clinical imperative, targeted interventions represent a substantial economic opportunity to reshape the landscape of respiratory care across these conditions [62].
For asthma, the most impactful economic strategy is reducing costly emergency care through improved integration of primary care and access to medications. Embedding asthma diagnosis and management within primary health care systems can substantially reduce emergency department visits and hospitalizations [63,64]. This can be achieved through task-shifting to trained community health workers, implementation of digital adherence monitoring, personalized action plans, and a global commitment to ensuring universal affordability of essential inhaled drugs.
For COPD, the economic burden of advanced disease can be mitigated by shifting focus upstream toward early detection and aggressive risk factor modification. Integrating spirometry into primary care for at-risk populations (e.g., smokers and individuals exposed to biomass smoke) enables earlier intervention, slowing disease progression and preserving lung function, thereby reducing long-term disability costs.
The most significant future economic opportunity lies in prevention. Policies aimed at reducing fossil fuel use not only mitigate climate change but also directly decrease ambient air pollution (PM2.5, NO2), a major contributor to COPD. Expanding access to clean cooking fuels and technologies in LMICs addresses household air pollution, particularly among women. These “win-win” environmental strategies represent long-term investments in lung health with substantial economic returns through reduced health care utilization and increased productivity, aligning with the principles of planetary respiratory medicine.
The economic outlook for ILDs depends on improving diagnostic efficiency and expanding access to effective therapies. Currently, diagnosis is often delayed and resource-intensive, involving multiple specialist consultations and procedures. Broader implementation of MDT evaluations, including via telemedicine, may facilitate earlier and more accurate diagnosis, reducing ineffective treatments and associated costs.
Future advances, including blood-based biomarkers and algorithm-driven diagnostic tools, may enable earlier and more cost-effective screening of high-risk populations (e.g., individuals with connective tissue diseases or occupational exposures). As antifibrotic therapies evolve, value-based pricing strategies will be essential to ensure equitable access while maintaining sustainability of health care systems.
Addressing smoking offers the greatest return on investment in respiratory health. Beyond direct medical costs, smoking imposes a substantial economic burden through lost productivity, premature mortality, and disability. Full implementation of WHO MPOWER measures, particularly increased tobacco taxation, remains the most cost-effective strategy.
Innovative approaches include integrating smoking cessation services into nontraditional settings. Leveraging digital therapeutics, expanding access to quitlines, and embedding cessation support within mental health and substance use programs—where smoking prevalence is disproportionately high—can address underlying socioeconomic determinants.
Collectively, these targeted interventions can improve health equity while generating significant economic savings by focusing on high-risk and high-cost populations.
A syndemicThe four major respiratory conditions reviewed—asthma, COPD, ILD, and smoking—demonstrate a convergent pattern of shared determinants operating across environmental, social, and clinical domains [65]. Despite distinct pathophysiological mechanisms, they are collectively driven by exposure to inhaled toxicants, including ambient and household air pollution, occupational hazards, and tobacco smoke, all of which are amplified by socioeconomic inequalities that influence both exposure risk and access to care [34].
This intersection highlights that respiratory health extends beyond clinical boundaries and serves as an indicator of environmental integrity, population health, and social equity. The emerging concept of planetary respiratory medicine provides a unifying framework for addressing this syndemic [66,67].
Planetary respiratory medicine conceptualizes respiratory health not solely as an individual clinical outcome but as a reflection of interconnected human, animal, and environmental systems [68]. It emphasizes understanding, preventing, and managing respiratory diseases by addressing shared environmental and anthropogenic drivers at a global scale [69].
CRDs share common root causes linked to human activity, including exposure to outdoor and indoor air pollution (from fossil fuels and biomass), climate change (affecting aeroallergen patterns and air quality), occupational exposures, and the widespread influence of tobacco and its derivatives. This framework extends beyond traditional disease management toward a life-course approach emphasizing primary prevention, interconnected determinants, and health equity [70].
By integrating a One Health perspective—linking human, animal, and environmental health—this approach advocates for comprehensive lung health promotion, primarily through prevention (Fig. 5) [71,72]. Coordinated action addressing clean air, tobacco control, occupational safety, and climate change mitigation is essential to reducing the global respiratory burden [73].
Such an approach bridges population-level determinants and individual clinical care [74], offering a comprehensive roadmap for policy and practice necessary for sustainable health in the 21st century.
ConclusionsAsthma, COPD, ILD, and tobacco smoking collectively represent a substantial and growing global public health challenge. These conditions share common risk factors, including environmental exposures (tobacco smoke, air pollution, occupational agents) and socioeconomic determinants that perpetuate health inequalities [75].
COPD burden reflects cumulative exposure to risk factors such as smoking, pollution, and occupational hazards, whereas asthma mortality highlights disparities in access to care. ILD epidemiology is strongly influenced by diagnostic capacity, and smoking acts as a unifying and compounding risk factor across all conditions.
Challenges including underdiagnosis, limited access to care, and the need for more effective therapies are universal but disproportionately affect LMICs. Future burden will be shaped by global trends such as urbanization, climate change, population aging, and expansion of tobacco and nicotine product markets.
Addressing this burden requires a coordinated, multilevel response: primary prevention through strengthened environmental and tobacco control policies, secondary prevention through early detection in primary care, and tertiary prevention through equitable access to effective treatments and palliative care.
Respiratory health must be prioritized within global health agendas [76] and universal health coverage initiatives to reduce the substantial and preventable morbidity and mortality associated with these conditions.
Conflicts of interestJBS has received pharmaceutical company grants from 2021 to 2025 from Chiesi, GSK, Linde and Novartis via Hospital Universitario de La Princesa. Participated in speaking activities, advisory committees, and consultancies from 2021 to 2025 sponsored by Air Liquide, Almirall, AstraZeneca, Boehringer Ingelheim, CHEST, Chiesi, CNPT, ERS, FTH, Gebro, Grifols, GSK, IHME, Laminar Pharma, Linde, Lipopharma, Menarini, Mundipharma, Novartis, OMS/WHO, Pfizer, ResApp, RiRL, ROVI, SEPAR, SAPIO, Seqirus, WHO EUR, Takeda and Zambon. Finally, JBS declares never received, directly or indirectly, any funding from tobacco manufacturers or their affiliates.
JL LC reports grants or contracts from Menarini; Consulting fees from GlaxoSmithKline, Menarini, Zambon, Gebro and Sanofi; Payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Grifols, Sanofi, AstraZeneca, CSL Behring, Bial, Faes Pharma, Menarini, GSK, Gebro and Chiesi; Support for attending meetings and/or travel from Grifols, Chiesi and Gebro.
Given their role as Editor-in-Chief, JL LC had no involvement in the peer-review of this article and has no access to information regarding its peer-review. Full responsibility for the editorial process for this article was delegated to another journal editor.
Authors’ contributionsAll authors contributed equally to this submission.
StatementsNo part of the research presented has been funded by tobacco industry sources. All authors have read the manuscript and approved its submission. This is the first journal assessing this work, following an invitation for a Review Article dated 21 November 2025. This submission does not contain material that has been submitted or published elsewhere.
Author comments upon submissionWe had full access to all data in this study and take complete responsibility for the integrity of the data and the accuracy of the data analysis.
Use of artificial intelligenceThe manuscript content is entirely original and authored by the authors. No artificial intelligence tools were used in its preparation, except for Fig. 5, which was generated with the assistance of ChatGPT 5.2.
FundingNone declared.
