Spatiotemporal Dynamics, Source Apportionment, and Stochastic Health Risk Assessment of Volatile Organic Compounds in Almaty, Kazakhstan

Urban air pollution in Central Asia remains a critical challenge, with volatile organic compounds (VOCs) posing significant threats to public health and regional climate stability. This research integrates studies conducted in Almaty, Kazakhstan, between 2015-2023 to characterize VOC concentrations, identify emission sources, and quantify human health risks [1-4].In Almaty, the COVID-19 lockdown period in 2020 provided a unique opportunity to observe air quality under traffic-free conditions. While traffic-related pollutants (CO and NO2) decreased by 49% and 35%, benzene and toluene levels remained 2–3 times higher than in the same seasons of 2015-2019. These results indicate that VOC pollution is dominated by non-traffic sources, such as coal-fired combined heat and power plants (CHPs) and residential heating systems. During the lockdown, people remained at home, potentially increasing coal combustion for private heating and public bathhouses (saunas) [1].Throughout 2020, VOC concentrations in Almaty displayed significant seasonal and spatial variability. In total, 9 of 19 VOCs showed significant seasonal fluctuations, peaking during the winter heating season. Total VOC (TVOC) concentrations in January (233-420 µg/m3) weresubstantially higher than in summer. Spatially, TVOC levels correlated with Almaty’s northward-declining topography, increasing from southern upper to northern lower districts, closer to CHPs and characterized by stagnant conditions and persistent temperature inversions [2].Consequently, a stochastic human health risk assessment for Almaty residents revealed concerning long-term implications. Median non-carcinogenic Hazard Indices (HI-s) were generally within acceptable limits (