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Chronic Exposure to Charcoal Biomass Pollution: Effects on the Occurrence of Chronic Cardiovascular and Pulmonary Diseases, Aerobic Capacity, and the Cardiopulmonary Response to Exertion

par Lofuta Olenga Vuvu, Pierre Gaylord
Président du jury Faoro, Vitalie
Promoteur Deboeck, Gaël
Co-Promoteur Klass, Malgorzata
Publication Non publié, 2025-08-29

Thèse de doctorat

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Résumé :

Background. Charcoal production (CP) exposes workers to biomass smoke and dust containing particulate matter, volatile organic compounds, polycyclic aromatic hydrocarbons, and various toxic gases generated during the combustion and processing of charcoal. Chronic inhalation of these pollutants may impair lung function and promote the development of chronic respiratory and cardiovascular diseases, as well as reduce aerobic capacity and alter cardiopulmonary responses to exercise among exposed individuals. However, literature remains limited regarding the prevalence, and associated factors, of chronic diseases like chronic obstructive pulmonary disease (COPD) and hypertension among charcoal workers living in rural areas. These workers are exposed to occupational biomass pollutants from charcoal production. Moreover, the effects of chronic biomass exposure on exercise-induced physiological responses have not yet been documented.This thesis aims to contribute to the understanding of the cardiovascular and pulmonary effects of chronic exposure to charcoal biomass pollution, through three complementary studies focusing on functional and clinical alterations.Methods and main findings. Between August 2020 and July 2021, three analytical controlled studies, of which two cross-sectional and one prospective, were conducted in charcoal-producing provinces in southwestern Democratic Republic of Congo. Charcoal workers were compared to agricultural workers unexposed to occupational biomass.The first cross-sectional study assessed the prevalence and associated factors of COPD. It included 485 participants: charcoal producers (n = 229) compared to farmers (n = 118), and female charcoal saleswomen (n = 72) compared to vegetable saleswomen (n = 66). This study collected air quality measurements and sociodemographic, toxicological, clinical, and respiratory data, including spirometry and respiratory symptom assessments. COPD was identified in the context of biomass exposure according to recent definitions from the European Respiratory Society and the Global Lung Initiative. The results showed that the working environment of charcoal workers was more polluted than that of farmers, and charcoal workers had a two- to threefold higher risk of developing COPD compared to farmers. Occupational exposure to charcoal appears to be an independent risk factor for COPD, possibly surpassing the effect of smoking. Among women, being a charcoal saleswoman, younger age, and low income were also independently associated with COPD.The second cross-sectional study, using the same sample, explored the cardiovascular negative effects of biomass exposure. Following European Society of Hypertension criteria, it assessed the prevalence and risk factors of hypertension and elevated pulse pressure (PP), a marker of arterial stiffness. The study found that hypertension affected over one-quarter of charcoal workers with higher prevalence of isolated systolic hypertension and elevated PP among charcoal workers, despite their high levels of physical activity and relatively young age. Exposure to ultrafine and fine particulate matter (PM1,0 and PM10), work seniority, male sex, low educational level, and smoking were independently associated with these chronic cardiovascular disorders. These findings highlight the critical role of chronic biomass pollutant exposure in the early onset of arterial stiffness and cardiovascular events in these rural populations.The third study is prospective, it investigated aerobic capacity, cardiopulmonary responses to exercise, and the prevalence of exercise-induced bronchoconstriction. From the initial sample, 45 charcoal producers and 36 farmers, all healthy males aged 23 to 39 years, were included using a single-blind randomization. Participants performed Incremental Shuttle Walk and Run Tests over a 15-meter course. Distance covered was used to estimate aerobic capacity, while blood pressure, heart rate, and spirometry measurements were assessed before and after exercise to evaluate cardiopulmonary function. Both groups were comparable at baseline. Although aerobic capacity remained similar, after exercise, charcoal workers exhibited lower FEV1 values than farmers, slower FEV1 recovery, and a higher prevalence of exercise-induced bronchoconstriction. These results indicate exercise-related functional pulmonary impairment in workers exposed to charcoal pollutants.Conclusion. Collectively, these three studies provide converging evidence of the multisystemic adverse impact of occupational charcoal exposure, involving respiratory, cardiovascular, and exercise-related functional impairments. This thesis expands current knowledge on the health effects of biomass exposure and calls for the development of targeted clinical, public health, and policy interventions for charcoal workers.