Enhanced VOC emission with increased temperature contributes to the shift of O₃-precursors relationship and optimal...

Assessing the impact of anthropogenic volatile organic compounds (VOCs) on ozone (O₃) formation is vital for the management of emission reduction and pollution control. Continuous measurement of O₃ and the major precursors was conducted in a typical light industrial city in the YRD region from 1 May to 25 July in 2021. Alkanes were the most abundant VOC group, contributing to 55.0% of TVOCs concentration (56.43 ± 21.10 ppb). OVOCs, aromatics, halides, alkenes, and alkynes contributed 18.7%, 9.6%, 9.3%, 5.2% and 1.9%, respectively. The observational site shifted from a typical VOC control regime to a mixed regime from May to July, which can be explained by the significant increase of RO_x production, resulting in the transition of environment from NO_x saturation to radical saturation with respect to O₃ production. The optimal O₃ control strategy should be dynamically changed depending on the transition of control regime. Under NO_x saturation condition, minimizing the proportion of NO_x in reduction could lead to better achievement of O₃ alleviation. Under mixed control regime, the cut percentage gets the top priority for the effectiveness of O₃ control. Five VOCs sources were identified: temperature dependent source (28.1%), vehicular exhausts (19.9%), petrochemical industries (7.2%), solvent & gasoline usage (32.3%) and manufacturing industries (12.6%). The increase of temperature and radiation would enhance the evaporation related VOC emissions, resulting in the increase of VOC concentration and the change of RO_x circulation. Our results highlight determination of the optimal control strategies for O₃ pollution in a typical YRD industrial city.