Air pollution in the West Kazakhstan region: A multi-source analysis

This study presents an initial comprehensive analysis of the spatial and temporal distribution of atmospheric pollutants in the West Kazakhstan region, utilising satellite data acquired between 2020 and 2023 from the Sentinel-5 Precursor mission, which is equipped with the Tropospheric Monitoring Instrument. The work was based on integrating satellite observations with geostatistical methodologies, namely Getis-Ord Gi* and interquartile range (IQR) analysis. This combination of techniques enabled the identification of persistently polluted areas and the detection of spatial patterns that were not been previously encompassed by the ground-based monitoring network. The analysis covered four key pollutants: sulphur dioxide (SO 2 ), carbon monoxide (CO), nitrogen dioxide (NO 2 ), and methane (CH 4 ). Steable seasonal trends were recorded, including SO 2 and CO winter peaks, NO 2 episodic increases, and weakly pronounced CH 4 dynamics. The Getis-Ord Gi* method was used to identify pollution hotspots with high statistical significance. The IQR analysis identified zones with consistently high SO 2 concentrations beyond the limits of the existing observation network. The results obtained provide a foundation for the subsequent environmental zoning of the region, the enhancement of atmospheric monitoring strategies, and the evaluation of risk in industrial areas characterised by constrained observation infrastructure.