War-time changes in air pollution across Ukrainian cities were assessed through magnetic susceptibility and heavy metal contents in particulate matter collected on air filters.

This study examines changes in air pollution by magnetic iron compounds and heavy metals, as identified through magnetic susceptibility and Fe, Zn, Cu, Mn, Pb, Ni, and Cr content measurements on air filters collected monthly during the pre-war (PW-01.2016-12.2018) and war (W-08.2023-02.2025) periods from the monitoring system in three Ukrainian cities located within 40 km of the Russian-Ukrainian war frontline. A general improvement in air quality in the three cities has been recognized from decreases in magnetic susceptibility (kV) and metal concentrations, attributable to the broader impacts of the ongoing war. A sharp decline in kV was caused by the destruction of industrial facilities in Kharkiv and a significant reduction in traffic intensity due to a 5-fold depopulation in Kherson. The persistent operation of metallurgical industries in Zaporizhzhia throughout the war caused sustained high content of magnetic compounds in urban air. Source apportionment provided insight into war-related variations in particulate matter composition, influencing urban air quality. Principal Component Analyses revealed shifts in iron and steel production in Zaporizhzhia; disruptions in the machine-building industry, which involves stainless-steel processing, in Kharkiv; and reduced traffic intensity and extensive use of house ovens in Kherson. The mitigation of urban air contamination is indicated by modified Pollution Load Index values below 1, reflecting wartime changes in the concentrations of Cu, Pb, Zn, Ni, Cr, and Mn compared to the PW period. Thus, war-related shifts in human impact on the urban environment closely align with population decline, changes in industrial activity, and alterations in energy supply. Considering the ongoing military conflict and the high population density in urban areas, sustained monitoring and effective control of air quality are essential.