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The Impact of Air Pollution on COPD and Asthma: Risks and Health Consequences

Original Editor - Lukas Winkler Top Contributors - Ferdinand Morandell, Vidya Acharya, Uchechukwu Chukwuemeka and Srishti Banerjee

Introduction

Chronic obstructive pulmonary disease (COPD) and asthma are two of the most common respiratory diseases in the world. An umbrella review of systematic reviews and meta-analyses concluded that smoking, body mass index, air pollution, early life exposures, and occupational hazards are nongenetic risk factors for both COPD and adult-onset asthma.[1] According to the fixed-ratio diagnostic criterion, a 2024 meta-analysis and systematic review of spirometry-based studies found the overall prevalence of COPD at 12.16% (95% CI 10.91–13.40%), with a higher prevalence in men (15.70%) than in women (9.93%).[2] Tobacco smoking is the primary risk factor for COPD, along with occupational exposure to harmful particles and gases.[3]

Asthma has an equally significant burden.[4] According to a 2025 analysis of Global Burden of Disease (GBD) 2021 data, 260 million people worldwide were estimated to have asthma in 2021. Since 1990, the age-standardised prevalence rate has decreased by 40%, from 5,568 to 3,340 cases per 100,000 people, a trend attributed to advancements in diagnosis and treatment.[5] The Global Asthma Report estimates that the prevalence of asthma symptoms is currently 9.1% in children, 11.0% in adolescents, and 6.6% in adults. The prevalence varies between 1% and 29% depending on the nation.[6] Environmental exposures, lifestyle choices, and genetic predisposition are common risk factors for both illnesses. One of the most important environmental risk factors for respiratory diseases is air pollution.[7]

Air pollution is defined as the presence of substances that are harmful to human health in the atmosphere, either from human activity or from natural events like wildfires or volcanic eruptions. When it comes to the extent and duration of exposure, anthropogenic sources are significantly more significant. Approximately three billion people are exposed to poor air quality due to solid fuel use, and over 80% of people living in urban areas where air pollution is monitored are exposed to pollutant levels exceeding World Health Organisation guidelines. While air quality is improving in many developed countries, it is still declining in developing countries.[8]

Particulate matter (PM) and gaseous components are the two main categories of air pollution in metropolitan settings. Ozone (O3), carbon monoxide (CO), sulphur dioxide (SO2), nitrogen oxides (NOx), and volatile organic compounds (VOCs) are examples of gaseous components.[9] Because of its impact on the immune system, PM has drawn special interest from researchers.[10]PM is divided into three categories based on aerodynamic diameter: ultrafine particles, which have a diameter of less than 0.1 micrometres, PM2.5, which has a diameter of less than 2.5 micrometres, and PM10, which has a diameter of less than 10 micrometres.[9] Because they can enter the lower respiratory tract and, in the case of ultrafine particles, the bloodstream, smaller particles like PM10 and PM2.5 are especially dangerous.[9] With an estimated population attributable proportion of 14%,[3] occupational exposure to dusts, chemical vapours, gases, and fumes is another significant and frequently overlooked risk factor that contributes to the onset and progression of COPD.

This page provides summary of the pathophysiology of asthma and COPD throughout life, explains how air pollution causes these illnesses, and offers helpful advice for both patients and medical professionals. It also considers future challenges for the healthcare system in the context of rising rates of pollution-related respiratory disease.

Chronic Obstructive Pulmonary Disease

COPD

Chronic Obstructive Pulmonary Disease is a progressive, multifaceted, and avoidable respiratory disorder characterised by recurrent airflow restriction and chronic inflammation of the airways. Spirometric confirmation of a post-bronchodilator forced expiratory volume in one second to forced vital capacity ratio (FEV1/FVC) of less than 0.70 is required for the diagnosis, as per the Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2025 guidelines.[11] Although air pollution, occupational exposures, and developmental variables are all known causes, tobacco smoking continues to be the primary aetiological risk. In addition to the well-established function of innate immunity, there is mounting evidence that adaptive immune cells play a part in the gradual lung damage associated with emphysema.[12] The condition is marked by structural changes in the airways, which are usually accompanied by mucociliary dysfunction, chronic bronchitis, and emphysema (the destruction of alveolar tissue). Patients typically experience recurring lower respiratory tract infections that linger for more than two weeks, along with dyspnoea, coughing, and sputum production.[13]

Acute exacerbations of COPD (AECOPD), which are characterised as persistent worsening of respiratory symptoms necessitating further therapy, are a significant cause of hospitalisation and are often brought on by environmental variables, such as high PM concentrations.[14] Cardiovascular disease, anxiety, and depression are major comorbidities with COPD, and they all increase total morbidity and death. It should be mentioned that a person may have both COPD and asthma; this is known as asthma-COPD overlap syndrome.[15]

Asthma

Asthma

Asthma is a common disease in paediatric and adult populations, and is recognised as a multifaceted chronic inflammatory disease of the airways, frequently classified by endotype to support more personalised, biomarker-driven treatment.[4]

The current Global Initiative for Asthma (GINA) strategy report states that asthma is described by a history of respiratory symptoms, such as wheezing, shortness of breath, chest tightness, and cough, which change over time and in intensity, along with fluctuating expiratory airflow limitation.[16] Mucus hypersecretion, airway wall remodelling, and bronchial hyperresponsiveness, the increased bronchoconstrictor reaction of the airways to non-specific stimuli, are all brought on by airway inflammation.

The clinical characteristics of childhood-onset and adult-onset asthma are different, with adult-onset asthma typically being more severe and less often linked to atopy.[17] Atopy, decreased lung function, and respiratory viral infections, especially rhinovirus, are important risk factors for the persistence of the condition in children. Controlling underlying airway inflammation and preventing exacerbations are the main treatment objectives. In addition to recommending inhaled corticosteroid-containing regimens as first-line management for adults and adolescents, the current GINA report still advises against treating asthma patients solely with short-acting beta-agonists. It also includes specific recommendations regarding the impact of extreme weather and climate change on persons with asthma.[16]

Causes of Air Pollution

Fumes

Air pollution is an intricate and dynamic blend of gases, PM, and liquid aerosols that constantly interact with natural atmospheric components. Fossil fuel burning, which powers transportation, industrial production, and electrical generation, is the main cause of anthropogenic air pollution. One of the main modifiable risk factors for respiratory diseases, along with cigarette smoking, is exposure to atmospheric pollution suspended in humid air, or "smog," which is made up of dust particles of various sizes as well as non-metal oxides, organic compounds, and heavy metals.[10]

The main human-caused sources of PM2 in developed and high-income nations are industrial operations, power generation, and traffic.[7] While fine and ultrafine particles can directly enter the lung's gas exchange area and, in the case of the tiniest particles, pass through the blood-air barrier to enter the circulatory system, coarse particles can often penetrate the upper bronchi.[9] Particularly in youngsters, exposure to indoor and outdoor pollution has been shown to have a detrimental effect on the onset and maintenance of asthma.[8]

Volcanic eruptions, desert dust storms, and wildfires, the latter of which is becoming more concerning due to the accelerated effects of climate change, are examples of natural sources of air pollution.[18] However, when it comes to the long-term effects on public health, man-made emissions continue to outweigh natural sources.[19]

Effect of Air Pollution on Asthma and COPD

Numerous non-communicable diseases, including respiratory, metabolic, and cardiovascular disorders, are exacerbated by air pollution. Health depends on a healthy immune system, and knowing how ambient contaminants impact immune function is vital to comprehending how pollution causes illness. Particle size and the water solubility of gases affect how deeply inhaled pollutants enter the respiratory system; smaller particles enter the distal airways and alveolar spaces more profoundly. Pollutants produce reactive oxygen species when they come into contact with the airway epithelium, which sets off inflammatory cascades.[20] Asthma risk is significantly correlated with exposure to nitrogen dioxide, ozone, PM10, PM2.5, and air pollution from traffic.[8]

Elevated pollutant levels are linked to higher symptom prevalence, higher medication needs, and higher mortality rates in people who already have asthma.[21] Due to their undeveloped immune systems, higher respiratory rates in relation to body weight, dynamic lung growth, and increased outside exposure, children are especially vulnerable.[21] The immune system is impacted by climate change and the corresponding increase in air pollution through mechanisms that lead to the development of asthma and allergic diseases.[22] Pro-inflammatory cytokines and Th2-driven immune responses are released as a result of oxidative stress-mediated airway inflammation, breakdown of the bronchial epithelial barrier, and increased allergen immunogenicity through binding to PM.[23]

Increased permeability and immune activation caused by disruption of the epithelial barrier lead to immunological dysregulation, dysbiosis, and the development or aggravation of allergic respiratory diseases.[24] PM2.5 is linked to COPD prevalence, morbidity, and acute exacerbations, and there is epidemiological evidence that ambient PM exposure worsens COPD outcomes. Studies and meta-analyses report different effect sizes. [14] For example, independent meta-analyses estimate that every 10 µg/m³ increase in PM2.5 is linked to roughly a 1.6% to 2.5% increase in hospital admissions related to COPD, though estimates vary depending on study population and methodology.[14]

PM2.5 and other airborne particles, such as ozone, sulphur dioxide, and nitrogen dioxide, are linked to the development of emphysema and chronic bronchitis by causing airway inflammation, protease release, and epithelial tissue destruction. PM2.5 impairs mucociliary clearance by interfering with cilia movement and increasing mucus formation in airway epithelial cells.[14]

Measures to Improve Air Quality

Coordinated government effort, better home practices, and focused investment based on scientific data are all necessary to combat air pollution. By requiring lower automobile emission limits, investing in public transportation infrastructure, encouraging the electrification of goods and passenger transportation, and enforcing stronger industrial emission restrictions, governments can minimise ambient pollution.[25]

In urban environments, integrating green spaces and vegetation into the built environment offers supplementary benefits, including improved air quality, promotion of biodiversity, and encouragement of physical activity, as identified by the World Economic Forum among strategies for tackling air pollution and climate change together.[26]

At the individual level, conserving household energy, switching to renewable energy sources where possible, reducing car use in favour of walking, cycling, or public transport, and choosing electric vehicles when motorised transport is necessary are all meaningful contributions that individuals can make towards reducing personal exposure and contribution to fossil fuel emissions.[10]

Recommendations for People with COPD and Asthma

People with COPD or asthma should minimise exposure to polluted air as far as practicable, particularly during periods when ambient pollution is highest. Air quality indices published by national environmental agencies can be checked for the level of pollution in a given region, and strenuous outdoor activity should be avoided when pollution is high.

For indoor air quality, attempts should be made to reduce pollutant sources within the home. Candles, incense, and open or solid-fuel fires should be avoided where possible. When cooking, an extractor fan should be used, and when cleaning, a vacuum cleaner fitted with a high-efficiency particulate air filter should be used in preference to sweeping, which can resuspend settled particles.

Air cleaners and regular ventilation can further improve indoor air quality, and these measures are relevant not only at home but also in schools and other settings where people spend extended periods of time.[10]

Breathing Exercises for Patients with Asthma or COPD

Breathing exercises play a role in the physiotherapy management of patients with asthma and COPD. These techniques aim to improve lung function, strengthen respiratory muscles, and alleviate symptoms such as breathlessness.

  • Inspiratory muscle training (IMT) aims to strengthen the inspiratory muscles, including the diaphragm and intercostal muscles, using devices with adjustable resistance. A 2021 systematic review and meta-analysis of breathing exercises in COPD found a significant total effect on inspiratory muscle strength (mean difference 8.65 cmH2O, 95% CI 3.13–14.16) and on six-minute walk distance (mean difference 27.70 metres, 95% CI 5.45–49.94), but found no significant improvement in quality of life.[27] This null finding on quality of life is consistent with the earlier 2012 Cochrane review of breathing exercises in COPD, which similarly found improved functional exercise capacity but no consistent effect on dyspnoea or health-related quality of life.[28] Taken together, these two reviews, separated by roughly a decade, point to a consistent pattern in the evidence: breathing exercises in COPD reliably improve objective measures of respiratory muscle strength and exercise capacity, but the evidence for improved patient-reported quality of life and symptom burden specifically remains weak and should not be overstated to patients.

In both pursed lip and diaphragmatic breathing techniques, patients are typically guided to place one hand on the chest and one on the abdomen, inhaling deeply through the nose so that the abdomen rises while the chest remains relatively still, before exhaling slowly through the mouth or pursed lips. These methods aim to promote more relaxed, efficient breathing and to reduce the work of breathing.[27]

  • Resistive breathing exercises use devices that provide resistance to both inhalation and exhalation, training both inspiratory and expiratory muscle groups through slow, controlled breathing, building on the same principles underlying inspiratory muscle training.

Conclusion

Air pollution is a major, largely modifiable risk factor for developing and worsening COPD and asthma. The repercussions of industrialisation and the usage of fossil fuels disproportionately affect people who live in urban and industrial areas, especially in developing nations. Oxidative stress, pro-inflammatory cytokine release, disruption of the epithelial barrier, and structural airway remodelling are among the increasingly well-characterised pathogenic processes by which PM and gaseous pollutants harm the respiratory tract.

Air pollution is mostly caused by human activity, namely the burning of fossil fuels for transportation and electricity. However, natural events like dust storms, volcanic eruptions, and wildfires also have a role.[25] The most recent extensive Lancet Countdown report on health and climate change highlighted the necessity of a health-centred response to these convergent crises, pointing out that delaying action continues to exacerbate the related health risks. Climate change and air pollution are closely related.[29] People with COPD and asthma should keep an eye on local air quality indices, refrain from doing so during periods of high pollution, and minimise indoor pollution sources by avoiding candles, incense, and open fires. They should also use air cleaners and adequate ventilation whenever possible, pending more significant structural and policy changes. As part of a broader pulmonary rehabilitation program, physiotherapists can help patients learn and prescribe appropriate breathing exercises.

Although the evidence for a consistent improvement in dyspnoea and quality of life in particular is less certain, breathing exercises, such as inspiratory muscle training, pursed-lip breathing, and diaphragmatic breathing, have shown benefit for measures like respiratory muscle strength and exercise capacity in some trials. These techniques should be incorporated into respiratory management programs under appropriate professional supervision rather than being presented as guaranteed to improve all outcomes.

References

  1. ↑ Holtjer JCS, Bloemsma LD, Beijers RJHCG, Cornelissen MEB, Hilvering B, Houweling L, et al. Identifying risk factors for COPD and adult-onset asthma: an umbrella review. Eur Respir Rev. 2023;32(168):230009. doi:10.1183/16000617.0009-2023
  2. ↑ Al Wachami N, Guennouni M, Iderdar Y, Boumendil K, Arraji M, Mourajid Y, et al. Estimating the global prevalence of chronic obstructive pulmonary disease (COPD): a systematic review and meta-analysis. BMC Public Health. 2024;24(1):297. doi: 10.1186/s12889-024-17686-9.
  3. ↑ 3.0 3.1 Murgia N, Gambelunghe A. Occupational COPD-The most under-recognized occupational lung disease? Respirology. 2022;27(6):399-410. doi: 10.1111/resp.14272.
  4. ↑ 4.0 4.1 Gans MD, Gavrilova T. Understanding the immunology of asthma: Pathophysiology, biomarkers, and treatments for asthma endotypes. Paediatr Respir Rev. 2020;36:118-127. doi: 10.1016/j.prrv.2019.08.002.
  5. ↑ Yuan L, Tao J, Wang J, She W, Zou Y, Li R, et al. Global, regional, national burden of asthma from 1990 to 2021, with projections of incidence to 2050: a systematic analysis of the global burden of disease study 2021. EClinicalMedicine. 2025;80:103051. doi: 10.1016/j.eclinm.2024.103051.
  6. ↑ Adam IF, FFPH-UK PJ. Global Asthma Report 2022. The Global Asthma Report 2022. 2022 Jan 1.(accessed 30 June 2026)
  7. ↑ 7.0 7.1 Bronte-Moreno O, González-Barcala FJ, Muñoz-Gall X, Pueyo-Bastida A, Ramos-González J, Urrutia-Landa I. Impact of Air Pollution on Asthma: A Scoping Review. Open Respir Arch. 2023;5(2):100229. doi: 10.1016/j.opresp.2022.100229.
  8. ↑ 8.0 8.1 8.2 Tiotiu AI, Novakova P, Nedeva D, Chong-Neto HJ, Novakova S, Steiropoulos P, et al. Impact of Air Pollution on Asthma Outcomes. Int J Environ Res Public Health. 2020;17(17):6212. doi: 10.3390/ijerph17176212.
  9. ↑ 9.0 9.1 9.2 9.3 Manisalidis I, Stavropoulou E, Stavropoulos A, Bezirtzoglou E. Environmental and Health Impacts of Air Pollution: A Review. Front Public Health. 2020;8:14. doi: 10.3389/fpubh.2020.00014.
  10. ↑ 10.0 10.1 10.2 10.3 Grzywa-Celińska A, Krusiński A, Milanowski J. 'Smoging kills' – effects of air pollution on human respiratory system. Ann Agric Environ Med. 2020;27(1):1–5. doi:10.26444/aaem/110477
  11. ↑ Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global Strategy for the Diagnosis, Management and Prevention of COPD: 2026 Report. Fontana, WI: GOLD; 2025. (accessed 30 June 2026)
  12. ↑ Kheradmand F, Zhang Y, Corry DB. Contribution of adaptive immunity to human COPD and experimental models of emphysema. Physiol Rev. 2023;103(2):1059-1093. doi: 10.1152/physrev.00036.2021.
  13. ↑ Gomes F, Cheng SL. Pathophysiology, Therapeutic Targets, and Future Therapeutic Alternatives in COPD: Focus on the Importance of the Cholinergic System. Biomolecules. 2023;13(3):476. doi: 10.3390/biom13030476.
  14. ↑ 14.0 14.1 14.2 14.3 Wang Q, Liu S. TThe Effects and Pathogenesis of PM2.5 and Its Components on Chronic Obstructive Pulmonary Disease. Int J Chron Obstruct Pulmon Dis. 2023;18:493-506. doi: 10.2147/COPD.S402122.
  15. ↑ Sayyeda F, Ali IAH, Harun SN, Tan ML. Asthma and chronic obstructive disease overlap (ACO), a systematic review of prevalence and co-morbidity factors based on diagnostic criteria. Journal of Pharmaceutical Policy and Practice [Internet]. 2026;19(1):2654490. doi:10.1080/20523211.2026.2654490
  16. ↑ 16.0 16.1 Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention: 2025 Update. Fontana, WI: GINA; 2025. Available from: https://ginasthma.org/2025-gina-strategy-report/ (accessed 30 June 2026)
  17. ↑ Melén E, Zar HJ, Siroux V, Shaw D, Saglani S, Koppelman GH, et al. Asthma Inception: Epidemiologic Risk Factors and Natural History Across the Life Course. Am J Respir Crit Care Med. 2024;210(6):737-754. doi: 10.1164/rccm.202312-2249SO.
  18. ↑ Xu R, Ye T, Huang W, Yue X, Morawska L, Abramson MJ, et al. Global, regional, and national mortality burden attributable to air pollution from landscape fires: a health impact assessment study. Lancet. 2024;404(10470):2447-2459. doi: 10.1016/S0140-6736(24)02251-7.
  19. ↑ eBioMedicine. Wildfires, smog, and the persistent threat of air pollution to human health. EBioMedicine. 2025;112:105602. doi: 10.1016/j.ebiom.2025.105602.
  20. ↑ Taylor-Blair HC, Siu ACW, Haysom-McDowell A, Kokkinis S, Saeid AB, Chellappan DK, et al. The impact of airborne particulate matter-based pollution on the cellular and molecular mechanisms in chronic obstructive pulmonary disease (COPD). The Science of the Total Environment [Internet]. 2024;954:176413. doi:10.1016/j.scitonv.2024.176413
  21. ↑ 21.0 21.1 Shi W, Kaewsanmung S, Kiratipaisarl W, Sapbamrer R. Outdoor air pollutants and asthma risk in adolescents: evidence from a systematic review and meta-analysis. Front Public Health. 2025;13:1721233. doi: 10.3389/fpubh.2025.1721233.
  22. ↑ Sampath V, Aguilera J, Prunicki M, Nadeau KC. Mechanisms of climate change and related air pollution on the immune system leading to allergic disease and asthma. Semin Immunol. 2023;67:101765. doi: 10.1016/j.smim.2023.101765.
  23. ↑ Zhou X, Sampath V, Nadeau KC. Effect of air pollution on asthma. Ann Allergy Asthma Immunol. 2024;132(4):426-432. doi: 10.1016/j.anai.2024.01.017.
  24. ↑ Kim BE, Hui-Beckman JW, Nevid MZ, Goleva E, Leung DYM. Air pollutants contribute to epithelial barrier dysfunction and allergic diseases. Ann Allergy Asthma Immunol. 2024;132(4):433–439. doi:10.1016/j.anai.2023.11.014
  25. ↑ 25.0 25.1 Fuller R, Landrigan PJ, Balakrishnan K, Bathan G, Bose-O'Reilly S, Brauer M, et al. Pollution and health: a progress update. Lancet Planet Health. 2022;6(6):e535-e547. doi: 10.1016/S2542-5196(22)00090-0.
  26. ↑ World Economic Forum. The best ways to reduce air pollution and tackle climate change together. Geneva: WEF; 2024. Available from: https://www.weforum.org/publications/ global-risks-report-2024/. (Accessed 30 June 2026)
  27. ↑ 27.0 27.1 27.2 27.3 Yun R, Bai Y, Lu Y, Wu X, Lee SD. How Breathing Exercises Influence Respiratory Muscles and Quality of Life among Patients with COPD? A Systematic Review and Meta-Analysis. Can Respir J. 2021;2021:1904231. doi: 10.1155/2021/1904231.
  28. ↑ Holland AE, Hill CJ, Jones AY, McDonald CF. Breathing exercises for chronic obstructive pulmonary disease. Cochrane Database Syst Rev. 2012 Oct 17;10(10):CD008250. doi: 10.1002/14651858.CD008250.pub2.
  29. ↑ Romanello M, Napoli CD, Green C, Kennard H, Lampard P, Scamman D, et al. The 2023 report of the Lancet Countdown on health and climate change: the imperative for a health-centred response in a world facing irreversible harms. Lancet. 2023;402(10419):2346-2394. doi: 10.1016/S0140-6736(23)01859-7.
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