Abstract
BACKGROUND: Pneumonia remains a leading cause of morbidity and hospitalization in sub-Saharan Africa, yet the contributions of long-term environmental and infrastructural factors to its spatial distribution are poorly understood. Kinshasa, a rapidly expanding African megacity, experiences high levels of air pollution, substantial vegetation loss, and marked urban inequalities, potentially exacerbating respiratory vulnerability. METHODS: We conducted a retrospective ecological spatial study using 484,954 pneumonia hospital admissions recorded across 35 health zones in Kinshasa between 2018 and 2022. Long-term exposure to ambient air pollution (PM₂.₅, NO₂, CO), vegetation cover (NDVI), major road density, climatic indicators, and healthcare infrastructure were assessed via satellite-derived and geospatial data. Bayesian BYM2 negative binomial models were fitted to estimate age-stratified relative risks (RRs), accounting for spatial dependence and overdispersion. Sensitivity analyses were used to evaluate model robustness. RESULTS: Pneumonia incidence showed pronounced spatial heterogeneity, with persistent high-risk zones concentrated in central and northern districts. Children under five years of age accounted for 41% of the cases and presented a substantially higher cumulative incidence than older individuals did. After adjustment for spatial effects and multicollinearity, no air pollutant demonstrated a consistent positive association with pneumonia risk. In contrast, vegetation cover was a robust protective factor across all age groups (RR range: 0.58-0.85). Higher major road density was also associated with reduced risk, likely reflecting improved accessibility and urban infrastructure. Areas combining low vegetation, high climatic stress, and limited infrastructure experienced the highest pneumonia burden. CONCLUSIONS: Pneumonia risk in Kinshasa is driven primarily by environmental and infrastructural inequalities rather than by the isolated effects of individual air pollutants. Strengthening urban green infrastructure, reducing environmental stressors, and improving equitable access to healthcare should be central to pneumonia prevention strategies in rapidly urbanizing African cities.