Ozone (O
3) pollution has become an increasing concern in China since elevated surface O
3 concentrations were observed in recent years. In this study, five provincial cities (Beijing, Shanghai, Guangzhou, Xi’an, and Hefei) located in different regions of China were selected
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Ozone (O
3) pollution has become an increasing concern in China since elevated surface O
3 concentrations were observed in recent years. In this study, five provincial cities (Beijing, Shanghai, Guangzhou, Xi’an, and Hefei) located in different regions of China were selected to study the spatiotemporal variations and affecting factors of O
3 concentrations during 2014–2015. Beijing, Shanghai, and Guangzhou had suffered more severe O
3 pollution, yet Beijing had the highest number of days that exceeded the Chinese MDA8 (maximum daily 8 h average) standard of 160 µg m
−3. MDA8 O
3 exhibited different seasonal patterns among the five cities. In Beijing and Xi’an, MDA8 O
3 showed the highest in summer and lowest in winter. Guangzhou also had the highest O
3 concentration in summer, but had similar levels in other three seasons. The O
3 levels were similarly high in Shanghai during spring, summer, and autumn, while in Hefei, O
3 concentration peaked in autumn. No significant difference between weekend and weekday O
3 levels was observed in all the five cities. The diurnal cycle reached a maximum in the afternoon and a minimum in the early morning, which was consistent in the five cities. Correlation analyses showed that the associations between O
3 and the other five criteria air pollutants, as well as meteorological parameters, were substantially different among the five cities. Air mass cluster analyses during episodic days revealed that the short-distance transport of O
3 and its precursors had a greater impact for high O
3 pollution in the five cities. Overall, our results demonstrate that O
3 pollution exhibited great divergence among different regions and thus region-oriented control measures are suggested to reduce O
3 pollution in China.
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