[Characteristics and Analysis of Typical Ozone Pollution Processes in Hebi]

Area of Science:

• Atmospheric Chemistry
• Environmental Science
• Air Pollution Research

Context:

• The Central Plains urban agglomeration, particularly Hebi City, experiences significant ozone (O3) pollution, lasting up to five months annually.
• A severe O3 pollution event from June 20-27, 2023, with an average hourly concentration of 256 μg·m⁻³, was analyzed.

Purpose:

• To characterize and analyze a typical ozone pollution process in Hebi City.
• To identify major ozone precursors and their sources using Positive Definite Matrix Factor Decomposition (PMF), emission inventories, and Ozone Formation Potential (OFP).
• To investigate the regional transport of ozone using the Potential Source Contribution Factor (PSCF) and Concentration Weighting Trajectory (CWT) methods.

Summary:

• Ozone (O3) concentrations showed a strong positive correlation with Volatile Organic Compounds (VOCs) and a negative correlation with aromatic, alkane, and halogenated hydrocarbons, as well as NOx.
• Key VOCs contributing to ozone formation include isoprene, m/p-xylene, ethylene, 1,2,4-trimethylbenzene, hexanal, and toluene.
• Major VOC sources identified were solvent use (25.7%), process (23.1%), and mobile sources (20.4%). NOx emissions were primarily from fossil fuel combustion and mobile sources.
• Ozone pollution was influenced by air masses from surrounding cities (Xinxiang, Anyang, Zhengzhou) for anthropogenic sources and from southeastern areas (Zhoukou, Chuzhou) for natural sources.

Impact:

• Findings highlight the need to reduce VOC emissions from specific industries (coal chemical, fine chemical) and power generation in Hebi.
• Recommendations include stricter standards for machinery use at construction and agricultural sites.
• Emphasizes the importance of regional joint prevention and control strategies for effective ozone pollution management.