Blog
The Global breath: Understanding the impact of smoking and air-pollution on COPD
- by Hithesh K. Gatty, PhD
- 02 Aug 2026
Chronic Obstructive Pulmonary Disease (COPD) is no longer a “hidden” disease; it is now one of the top three causes of death globally [1]. While many associate the characteristic cough and shortness of breath solely with cigarette smoking, the reality of this condition varies dramatically depending on where you live in the world [1][2].
The smoking connection
In high-income countries (HICs) like the United States and the United Kingdom, tobacco smoking remains the dominant cause of COPD, linked to 80% to 95% of all cases [2][3]. For those who smoke, the risk is severe: smokers are estimated to be 12 to 13 times more likely to die from COPD than those who have never picked up a cigarette [4]
The damage caused by tobacco smoke is progressive and, in many cases, permanent, leading to persistent inflammation and irreversible airflow limitation [5][6].
A shifting global picture
Despite the strong link to smoking in HICs, the global burden of the disease is shifting. Nearly 90% of COPD deaths now occur in low- and middle-income countries (LMICs) [1]. Interestingly, in these regions, tobacco smoking accounts for only about 30% to 40% of cases [2].
This means that for a vast majority of the world’s population, other environmental factors are the primary drivers of lung disease.
The HO-1 Pathway: A Cellular Stress Response
Oxidative stress is central to COPD pathogenesis. Exposure to tobacco smoke, biomass fuel, and environmental pollutants induces inflammatory cascades within the airway epithelium. A key adaptive response to this assault is the upregulation of Heme Oxygenase-1 (HO-1), a cytoprotective enzyme activated during oxidative and inflammatory stress [4]. HO-1 catalyzes the degradation of heme. Biochemically, the reaction proceeds as follows:
Beyond cigarette: Non-smoking risk factors
If not smoking, what is causing the high prevalence of COPD in LMICs? The sources point to several critical “non-smoking” risk factors:
- Household Air Pollution: Nearly 3 billion people worldwide still rely on biomass fuels (wood, animal dung, and crop residues) or coal for cooking and heating [2]. In poorly ventilated homes, this exposure is a leading cause of COPD, particularly affecting women [1][2].
- Ambient Air Pollution: In some regions, outdoor particulate matter has surpassed smoking as the leading cause of COPD-related disability [2].
Early Life Factors: Factors like maternal smoking in utero, childhood respiratory infections, and even prior tuberculosis can hinder lung development and increase the risk of developing COPD later in life [1][2].
A path forward
While the causes of COPD are diverse, the message from health experts is clear: COPD is both preventable and treatable [1][6]. For some, prevention means smoking cessation; for others, it means improving air quality and reducing exposure to toxic fumes [1]. By understanding the unique drivers in different regions, global health initiatives can better target the root causes of this life-threatening condition.
Reference
[1] Carpagnano, G. E., Resta, O., Foschino-Barbaro, M. P., Gramiccioni, E., & Barnes, P.J. (2003). Increased inflammatory markers in the exhaled breath condensate of cigarette smokers. European Respiratory Journal, 21(4), 589-593. https://doi.org/10.1183/09031936.03.00022203
[2] Slebos, D. J., Ryter, S. W., & Choi, A. M. K. (2003). Heme oxygenase-1 and carbon monoxide in pulmonary medicine. Respiratory Research, 4, 7. https://doi.org/10.1186/1465-9921-4-7
[3] Jarvis, M. J., Russell, M. A. H., & Saloojee, Y. (1980). Expired air carbon monoxide: A simple breath test of tobacco smoke intake. British Medical Journal (BMJ), 281(6238), 484–485. https://doi.org/10.1136/bmj.281.6238.484
[4] National Institute for Health and Care Excellence (NICE). (2008). PH10 Stop smoking services, evidence review (CO validation at 4 weeks). (PDF). https://www.nice.org.uk/guidance/ng209/evidence/ph10-stop-smoking-services-february-2008-pdf-10892313614
[5] Montuschi, P., Kharitonov, S. A., & Barnes, P. J. (2001). Exhaled carbon monoxide and nitric oxide in COPD. Chest, 120(2), 496–501. https://doi.org/10.1378/chest.120.2.496
[6] Gatty Instruments AB (2025). https://gattyinstruments.com/
[7] SPIROLUFT: A Next Generation Breath Analyser Utilising Simultaneous Spirometry & Pulse Oximetry, Säfström, Felix, Master thesis, Uppsala University, Sweden https://uu.diva-portal.org/smash/get/diva2:1916914/FULLTEXT01.pdf
[8] The Role of Heme Oxygenase-1 in Pulmonary Disease, Laura E Fredenburgh, Mark A Perrella, S. Alex Mitsialis, Division of Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women’s Hospital; and Division of Newborn Medicine, Children’s Hospital, Boston, Massachusetts. https://www.researchgate.net/figure/Degradation-of-heme-by-HO-1-HO-1-catalyzes-heme-degradation-to-biliverdin-IX-CO-and_fig1_6812848
