[Ozone Pollution Characteristics and Sensitivity During the Ozone Pollution Days in Summer 2021 of Xinxiang City]

This study was based on the observation of volatile organic compounds (VOCs), conventional gaseous air pollutants, and meteorological parameters observed at the Xinxiang Municipal Party School site from June to August 2021. The ozone (O₃) characteristics and sensitivity of O₃ pollution days and the control strategy of its precursors were studied using an observation-based model (OBM). It was found that the meteorological conditions were characterized by high temperature, low humidity, and low pressure in O₃-pollution days. The concentrations of O₃ and its precursors all increased in the O₃ pollution days. Oxygenated volatile organic compounds (OVOCs) and alkanes were the highest-concentration components of VOCs on O₃ pollution days in Xinxiang, and OVOCs had the highest ozone formation potential (OFP) and hydroxyl (·OH) reactivity. According to the relative incremental reactivity (RIR) analysis, during the O₃ pollution days in Xinxiang, O₃sensitivity was in the VOCs-limited regime in June and in the transitional regime in July and August. Ozone production was more sensitive to alkenes and OVOCs. The RIR values of the precursors in June changed throughout the day, but O₃ sensitivity remained the VOCs-limited regime. In July and August, O₃ sensitivity was the VOCs-limited regime in the morning, transitional regime at noon, transitional and NO-limited regime, respectively in the afternoon. By simulating different precursor-reduction scenarios, the results showed that the reduction of VOCs was always beneficial to the control of O₃, whereas the reduction of NO had little effect on the control of O₃ and a risk of increasing O₃.