In China, ozone pollution has been severe over recent decades without effective ozone-oriented policies, although PM_2.5 pollution has significantly decreased due to a series of measurements. In this study, we explore whether the lessons from PM_2.5 mitigation could be implemented to control ozone precursors’ emissions to mitigate ozone pollution. We focus on North China Plain and Fenwei Plain (NCP+FP), which are two heavily polluted regions by ozone and PM_2.5, and also be the core for regional synergy strategy for PM_2.5 mitigation. We find that the transboundary anthropogenic impact from other regions contributes 12% of monthly average maximum daily 8-h average (MAMDA8) ozone pollution over NCP+FP, with maximum reaching over 30% in southern cities. We further reveal that the transboundary anthropogenic impact could be enhanced about 57% with 100% reduction over NCP+FP. This enhancement suppresses 24% of local emission reduction. The suppression effect on city level also could influence the benefit of local emission control. Compared to reducing 20% emissions uniformly over 60 cities within NCP+FP, over 10% difference in city level anthropogenic emissions only results in very slight variation in city level ozone pollution. Overall, our results reveal that regional synergy strategy for ozone mitigation needs to consider larger areas and the synchronism between cities and regions when reducing emissions is crucial for effective ozone control. This study provides practical and fundamental information for ozone mitigation pathway and ozone-oriented policy making.
 

Ozone,Transboundary transport,Emission reduction