Complex interplay between transboundary ozone and domestic emissions shapes surface ozone pollution in China

Summary

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