Responses of Ambient Ozone and Other Pollutants to COVID-19 Lockdown in Taiyuan, North China
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School of Environment and Safety Engineering, North University of China, Taiyuan, 030051, China
Jie Ren   

North University of China, China
Submission date: 2021-09-10
Final revision date: 2021-11-10
Acceptance date: 2021-11-13
Online publication date: 2022-03-23
Publication date: 2022-05-05
Pol. J. Environ. Stud. 2022;31(3):2823–2835
Coronavirus Disease 2019 (COVID-19) lockdown was related to a significant reduction in air pollutant emissions. However, severe air pollution events still occurred frequently in Taiyuan, north China. To better understand this unusual phenomenon, O3 and other pollutants have been investigated before, during and after the COVID-19 lockdown in the early 2020. Results show that PM10, PM2.5, SO2, NO2 and CO underwent a more marked reduction while O3 pollution was amplified during lockdown and the average concentrations O3-8hr during AL stage (101.92 μg m-3) exceeded its Grade I limiting value (100 μg m-3). O3 were negatively correlated with the other pollutants and positively correlated with temperature, visibility and the average solar irradiance during the daytime. The increase in daylight hours and average solar irradiance might be the key factors leading to the increase in O3 concentrations. The reduction of PM2.5 and NO2 promoted the rise in O3 during the lockdown. The majority of the O3 was likely formed by photooxidation in the shadow of Taiyuan and linked with air masses from the northern part of Shanxi Province before the lockdown and Henan, Hebei and Shandong during and after the lockdown.