Characterization, source apportionment, and health risk assessment of atmospheric particulate-bound mercury in Bishkek, Kyrgyzstan.

Air pollution has emerged as a pressing environmental issue worldwide, and particulate-bound mercury (PBM) is increasingly recognized as one of toxic atmospheric components with implications for human health. While PBM has been measured in various urban environments, multi-year observational datasets remain limited for Central Asia. Here we analyzed PBM in total suspended particulate samples collected in Bishkek, Kyrgyz Republic, over a five-year period from 2018 to 2023. Mean PBM concentrations were 182 ± 334 pg m-3, significantly above the global mean, but showed a decreasing trend linked to air pollution control measures. PBM concentration in cold season was 1.8-fold higher than that in warm season, consistent with enhanced coal-based heating demand and reduced atmospheric dispersion. Back-trajectory analysis further indicated that PBM in winter was dominated by anthropogenic emissions and dust events. Health risk assessment revealed that the hazard quotient (HQing) for children from atmospheric PBM exceeded 1 during peak concentrations. Risks were significantly amplified during dust storm events, reaching levels 1.5-2 times higher than during non-dust events periods. This multi-year PBM dataset provides new regional evidence for mercury seasonality and exposure risk in Central Asia and highlights the importance of episodic events for protecting vulnerable populations.