Work

Factors contributing to elevated springtime surface ozone levels in eastern China

Year: 2025

Type: article

Abstract: Springtime ozone levels in the North China Plain (NCP) exceed those in California by 50 %. The difference is even larger at 85 % when compared to the eastern U.S. Field measurements at a rural NCP site reveal reactive aromatics concentrations 6.2 times higher than California levels, respectively. Box model analysis demonstrates reactive aromatics contribute 73 % of the total ozone production. By redistributing reactive aromatics emissions based on industrial source patterns and implementing observation-constrained diurnal cycles, model performance improves significantly across the NCP region. This redistribution shifts the chemical regime from predominantly VOC-limited into a transition zone towards NO x -limited regime, reversing the effect of NO x reduction on ozone in the NCP region. The underestimation of reactive aromatics emissions has substantial public health implications through increased ozone-related mortality. Our findings underscore the critical need for improved characterization of industrial emissions in economically developing regions to enable effective air quality management strategies. • Spring ozone in NCP exceeded California by 50 % and the eastern U.S. by 85 % in 2018. • Reactive Aromatics drive 73 % of ozone production; model underestimates by up to 22 %. • Redistributing emissions and adding diurnal cycles greatly improve simulated ozone. • Emission redistribution shifts NCP from VOC-limited to more NO x -limited, reversing NO x sensitivity. • Misallocated aromatics emissions raise ozone mortality by ~50,000 deaths/year.

Source: The Science of The Total Environment

DOI: 10.1016/j.scitotenv.2025.180909