Divergent trends in near-surface ozone and nitrogen dioxide and ozone-attributable health burden in the Huaihe River Basin, China, 2013-2024.

Authors

Minxia Liu, Siqian Wang, Yi Yang

Published in

Environmental monitoring and assessment. Volume 198. Issue 9. Aug 15, 2026. Epub Aug 15, 2026.

Abstract

Near-surface ozone (O₃) has become an increasingly important air-quality and public-health concern in China, particularly in regions where reductions in nitrogen oxides have not been accompanied by corresponding decreases in photochemical pollution. The Huaihe River Basin is a densely populated and economically important region in eastern China, but long-term basin-scale evidence on the divergent evolution of O₃ and nitrogen dioxide (NO₂) and the associated health burden remains limited. In this study, we used high-resolution satellite-derived near-surface O₃, expressed as the maximum daily 8-h average, and NO₂ concentrations to assess their spatiotemporal patterns, long-term trends, hotspot redistribution, and persistence characteristics across the Huaihe River Basin during 2013-2024. Pixel-wise linear regression and the Hurst exponent were applied to diagnose historical trends and persistence, and BenMAP-CE was used to estimate O₃-attributable premature mortality and associated economic losses. Basin-wide O₃ showed a fluctuating but overall increasing trend, with a mean concentration of 104.15 μg m^-3 and OLS-derived annual linear trend of 2.792 μg m^-3 yr^-1. In contrast, NO₂ declined continuously, with a mean concentration of 29.86 μg m^-3 and OLS-derived annual linear trend of -1.385 μg m^-3 yr^-1. Both pollutants exhibited a pronounced north-south gradient, with higher concentrations mainly concentrated in southern Shandong, especially along the Jining-Linyi corridor, and lower levels in the western and southern mountainous margins. Seasonal patterns were also contrasting: O₃ peaked in summer and reached its minimum in winter, whereas NO₂ showed the opposite pattern. Spatial trend and hotspot analyses revealed an outward expansion of O₃-affected areas but a marked contraction of NO₂ hotspots, indicating a redistribution of exposure under divergent pollutant responses. Hurst-based diagnostics further showed that O₃ had a more spatially coherent historical persistence signal than NO₂, particularly in the central basin, suggesting that ozone pollution may remain a regional concern under comparable emission and meteorological conditions. The health assessment showed an overall increase in O₃-attributable premature mortality during the study period, with cardiovascular mortality representing the largest cause-specific component. Jiangsu and Shandong bore the greatest health and economic burdens because of the combined effects of elevated exposure and large exposed populations. By integrating satellite-based environmental monitoring, trend-persistence diagnostics, and health-burden assessment, this study provides basin-scale evidence for identifying persistent ozone-risk areas and prioritizing coordinated air-quality management in the Huaihe River Basin.

PMID:
42603231
Bibliographic data and abstract were imported from PubMed on 16 Aug 2026.

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