Abstract
Background ozone (O3), defined as O3 originating from transboundary transport and domestic natural precursors, has traditionally been viewed as largely unresponsive to domestic anthropogenic emissions, representing an uncontrollable baseline for a nation’s O3 pollution levels. However, this paradigm overlooks the chemical interactions between the cycled oxidants from transboundary O3 and domestic precursors. Here, we developed a novel expanded odd oxygen (Oy) tagged modeling framework to explicitly track the sources and full photochemical cycling of O3 and its radical reservoirs during a typical autumn O3 pollution episode in China. Our results demonstrated that interactions between transboundary O3 and domestic precursors accounted for 44% to 49% of surface O3 levels across Eastern China during the study period. Transboundary O3 played a dual photochemical role, simultaneously promoting O3 formation by serving as a major source of ROx radicals, while also suppressing the ozone-forming potential of domestic precursors through ROx removal and modulation of the OH turnover rate. Consequently, the interplay between background and domestic anthropogenic sources fundamentally shaped the ambient O3 formation regime. This work challenges the prevailing view of a chemically static background, redefining the “controllable” portion of O3 pollution and necessitating a reassessment of mitigation strategies from regional to intercontinental scales.
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Data availability
All the datasets used in this study are publicly accessible. The Final Operational Global Analysis (FNL) data (https://gdex.ucar.edu/datasets/d083002/) used for meteorological initial and boundary conditions, and National Centers for Environmental Prediction (NCEP) ADP Global Surface Observational Weather Data (https://gdex.ucar.edu/datasets/d461000/) used for observational nudging of surface meteorology were obtained from National Center for Atmospheric Research (NCAR) Geoscience Data Exchange (GDEX) Archive. The Community Atmosphere Model with Chemistry (CAM-chem) output data (https://www.acom.ucar.edu/cesm/subset.shtml) used for chemical initial and boundary conditions, and the Fire Inventory from NCAR (FINN) data (https://www.acom.ucar.edu/Data/fire/) used for wildfire emissions were provided by NCAR Research Data Archive. The Multi-resolution Emission Inventory (MEIC) data used for anthropogenic emissions were downloaded from MEIC official website (http://meicmodel.org.cn/?page_id=45&lang=en). Model of Emissions of Gases and Aerosols from Nature (MEGAN) data used for biogenic emissions were retrieved from NCAR Weather Research and Forecasting model coupled to Chemistry (WRF-Chem) Pre-processors Archive (https://www.acom.ucar.edu/wrf-chem/download.shtml).
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Acknowledgements
This work was supported by the National Key Research and Development Program of China (2023YFC3706205), the National Natural Science Foundation of China (42325504, 42305188), the Shenzhen Science and Technology Program (KQTD20210811090048025, JCYJ20220818100611024), and the High-level Special Funds (G03034K006). Computational resources were supported by the Center for Computational Science and Engineering at the Southern University of Science and Technology.
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Conceptualization: W.T. and T.M.F.; Funding acquisition: T.M.F. and M.S.; Supervision: T.M.F.; Methodology: W.T.; Investigation: W.T., A.Z., T.J., J.M., X.W., H.S., J.L., H.S., Y.C., R.N., and Y.G.; Formal analysis: W.T.; Software: W.T.; Visualization: W.T.; Writing-original draft: W.T. and T.M.F.; Writing—review and editing: W.T., T.M.F., J.L., H.S., Y.C., R.N., A.Z., Y.G., T.J., J.M., X.W., H.S., and M.S.
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Tao, W., Fu, TM., Liu, J. et al. Complex interplay between transboundary ozone and domestic emissions shapes surface ozone pollution in China. npj Clim Atmos Sci (2026). https://doi.org/10.1038/s41612-026-01379-8
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DOI: https://doi.org/10.1038/s41612-026-01379-8


