Assessing the PM<sub>2.5</sub>–O<sub>3</sub> Correlation and Unraveling Their Drivers in Urban Environment: Insights from the Bohai Bay Region, China

Understanding the correlation between PM<sub>2.5</sub> and O<sub>3</sub> is critical for complex air pollution control. This study comprehensively analyzed PM<sub>2.5</sub> and O<sub>3</sub> pollution characteristics, uncovered spatiotemporal variation...

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Main Authors: Yan Nie, Yongxin Yan, Yuanyuan Ji, Rui Gao, Yanqin Ren, Fang Bi, Fanyi Shang, Jidong Li, Wanghui Chu, Hong Li
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Atmosphere
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Online Access:https://www.mdpi.com/2073-4433/16/5/512
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author Yan Nie
Yongxin Yan
Yuanyuan Ji
Rui Gao
Yanqin Ren
Fang Bi
Fanyi Shang
Jidong Li
Wanghui Chu
Hong Li
author_facet Yan Nie
Yongxin Yan
Yuanyuan Ji
Rui Gao
Yanqin Ren
Fang Bi
Fanyi Shang
Jidong Li
Wanghui Chu
Hong Li
author_sort Yan Nie
collection DOAJ
description Understanding the correlation between PM<sub>2.5</sub> and O<sub>3</sub> is critical for complex air pollution control. This study comprehensively analyzed PM<sub>2.5</sub> and O<sub>3</sub> pollution characteristics, uncovered spatiotemporal variations in their correlation, and investigated the driving mechanisms of their association in Dongying, a typical petrochemical city in China’s Bohai Bay region. Results showed that PM<sub>2.5</sub>–O<sub>3</sub> correlation in Dongying exhibited significant seasonal variations, spatial patterns, and concentration threshold effects from 2017 to 2023. PM<sub>2.5</sub> and O<sub>3</sub> showed strong positive correlations in summer, negative in winter, and weak positive in spring/autumn, with strongest links in western areas. The strongest positive PM<sub>2.5</sub>–O<sub>3</sub> correlation occurred in summer when PM<sub>2.5</sub> ≤ 35 μg·m<sup>−3</sup> and O<sub>3</sub> >160 μg·m<sup>−3</sup>, while the strongest negative correlation was exhibited in winter with PM<sub>2.5</sub> > 75 μg·m<sup>−3</sup> and O<sub>3</sub> ≤ 100 μg·m<sup>−3</sup>. Meteorological conditions (T > 20 °C, RH < 30%, wind speed < 1.73 m/s, O<sub>x</sub> > 125 μg·m<sup>−3</sup>) and non-sea-breeze periods enhanced the PM<sub>2.5</sub>–O<sub>3</sub> positive correlation. During the four typical pollution episodes, the positive PM<sub>2.5</sub>–O<sub>3</sub> correlation in summer was propelled by synchronous increases in O<sub>3</sub> and secondary components via shared precursors. In autumn, strong positivity resulted from secondary component–O<sub>3</sub> correlations (r > 0.7) and dominance of secondary formation in PM<sub>2.5</sub>. In winter, the negative correlation stemmed from primary emissions inhibiting photochemistry. Random forest analysis showed that O<sub>x</sub>, RH, and T drove positive PM<sub>2.5</sub>–O<sub>3</sub> correlation via photochemistry in summer, whereas winter primary emissions and NO titration caused negative correlation. This study offers guidance for the collaborative PM<sub>2.5</sub> and O<sub>3</sub> control in the petrochemical cities of the Bay region.
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spelling doaj-art-dd813861b6ef4bab9e5d3f5aba57bbf72025-08-20T01:56:20ZengMDPI AGAtmosphere2073-44332025-04-0116551210.3390/atmos16050512Assessing the PM<sub>2.5</sub>–O<sub>3</sub> Correlation and Unraveling Their Drivers in Urban Environment: Insights from the Bohai Bay Region, ChinaYan Nie0Yongxin Yan1Yuanyuan Ji2Rui Gao3Yanqin Ren4Fang Bi5Fanyi Shang6Jidong Li7Wanghui Chu8Hong Li9State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, ChinaState Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, ChinaState Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, ChinaState Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, ChinaState Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, ChinaState Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, ChinaDongying Municipal Ecology and Environment Bureau, Dongying 257000, ChinaDongying Municipal Ecology and Environment Bureau, Dongying 257000, ChinaState Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, ChinaState Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, ChinaUnderstanding the correlation between PM<sub>2.5</sub> and O<sub>3</sub> is critical for complex air pollution control. This study comprehensively analyzed PM<sub>2.5</sub> and O<sub>3</sub> pollution characteristics, uncovered spatiotemporal variations in their correlation, and investigated the driving mechanisms of their association in Dongying, a typical petrochemical city in China’s Bohai Bay region. Results showed that PM<sub>2.5</sub>–O<sub>3</sub> correlation in Dongying exhibited significant seasonal variations, spatial patterns, and concentration threshold effects from 2017 to 2023. PM<sub>2.5</sub> and O<sub>3</sub> showed strong positive correlations in summer, negative in winter, and weak positive in spring/autumn, with strongest links in western areas. The strongest positive PM<sub>2.5</sub>–O<sub>3</sub> correlation occurred in summer when PM<sub>2.5</sub> ≤ 35 μg·m<sup>−3</sup> and O<sub>3</sub> >160 μg·m<sup>−3</sup>, while the strongest negative correlation was exhibited in winter with PM<sub>2.5</sub> > 75 μg·m<sup>−3</sup> and O<sub>3</sub> ≤ 100 μg·m<sup>−3</sup>. Meteorological conditions (T > 20 °C, RH < 30%, wind speed < 1.73 m/s, O<sub>x</sub> > 125 μg·m<sup>−3</sup>) and non-sea-breeze periods enhanced the PM<sub>2.5</sub>–O<sub>3</sub> positive correlation. During the four typical pollution episodes, the positive PM<sub>2.5</sub>–O<sub>3</sub> correlation in summer was propelled by synchronous increases in O<sub>3</sub> and secondary components via shared precursors. In autumn, strong positivity resulted from secondary component–O<sub>3</sub> correlations (r > 0.7) and dominance of secondary formation in PM<sub>2.5</sub>. In winter, the negative correlation stemmed from primary emissions inhibiting photochemistry. Random forest analysis showed that O<sub>x</sub>, RH, and T drove positive PM<sub>2.5</sub>–O<sub>3</sub> correlation via photochemistry in summer, whereas winter primary emissions and NO titration caused negative correlation. This study offers guidance for the collaborative PM<sub>2.5</sub> and O<sub>3</sub> control in the petrochemical cities of the Bay region.https://www.mdpi.com/2073-4433/16/5/512correlation between PM<sub>2.5</sub> and O<sub>3</sub>causal investigationmeteorological conditionsatmospheric oxidation capacityprecursorsbay area
spellingShingle Yan Nie
Yongxin Yan
Yuanyuan Ji
Rui Gao
Yanqin Ren
Fang Bi
Fanyi Shang
Jidong Li
Wanghui Chu
Hong Li
Assessing the PM<sub>2.5</sub>–O<sub>3</sub> Correlation and Unraveling Their Drivers in Urban Environment: Insights from the Bohai Bay Region, China
Atmosphere
correlation between PM<sub>2.5</sub> and O<sub>3</sub>
causal investigation
meteorological conditions
atmospheric oxidation capacity
precursors
bay area
title Assessing the PM<sub>2.5</sub>–O<sub>3</sub> Correlation and Unraveling Their Drivers in Urban Environment: Insights from the Bohai Bay Region, China
title_full Assessing the PM<sub>2.5</sub>–O<sub>3</sub> Correlation and Unraveling Their Drivers in Urban Environment: Insights from the Bohai Bay Region, China
title_fullStr Assessing the PM<sub>2.5</sub>–O<sub>3</sub> Correlation and Unraveling Their Drivers in Urban Environment: Insights from the Bohai Bay Region, China
title_full_unstemmed Assessing the PM<sub>2.5</sub>–O<sub>3</sub> Correlation and Unraveling Their Drivers in Urban Environment: Insights from the Bohai Bay Region, China
title_short Assessing the PM<sub>2.5</sub>–O<sub>3</sub> Correlation and Unraveling Their Drivers in Urban Environment: Insights from the Bohai Bay Region, China
title_sort assessing the pm sub 2 5 sub o sub 3 sub correlation and unraveling their drivers in urban environment insights from the bohai bay region china
topic correlation between PM<sub>2.5</sub> and O<sub>3</sub>
causal investigation
meteorological conditions
atmospheric oxidation capacity
precursors
bay area
url https://www.mdpi.com/2073-4433/16/5/512
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