Spatiotemporal heterogeneity in the association between ambient air pollution and respiratory morbidity in the industrial Region of East Kazakhstan

Ambient air pollution remains a significant risk factor for respiratory morbidity, yet its spatiotemporal associations in the industrial regions of Central Asia remain insufficiently studied. To identify the association between airborne pollutants and respiratory morbidity in four industrial settlements of East Kazakhstan Region and to determine the regional exposure profiles. Annual data for 2014–2024 were used for Ust-Kamenogorsk, Ridder, Altai, and Glubokoe. The analysis included H₂S, SO₂, CO, NO₂, API₅, and the overall incidence of respiratory diseases. Associations were evaluated using Spearman correlation with FDR correction. A one-year lag analysis, PCA, and peak-load analysis were additionally performed. After FDR correction, significant associations remained only in Altai and Glubokoe. In Altai, the most interpretable findings were positive associations of API₅ with morbidity across all age groups and of NO₂ with morbidity in adults. The associations for SO₂ were negative in direction. In Glubokoe, the strongest association was found between API₅ and morbidity in adolescents: ρ = 0.935; q = 0.0005. The lag analysis and the analysis of specific nosologies showed significant associations only in Glubokoe. Peak load had no robust association with the annual morbidity indicators. The association between air pollution and respiratory morbidity in East Kazakhstan Region is spatially heterogeneous. It is shaped not only by the level of industrial load but also by the structure of pollution, the territorial context, and the temporal scale of analysis. The findings support a territorially differentiated approach to environmental monitoring and to the assessment of public health risk.