Integrated process analysis retrieval of changes in ground-level ozone and fine particulate matter during the COVID-19 outbreak in the coastal city of Kannur, India

Fei Ye; Dipesh Rupakheti; Lin Huang; Nishanth T; Satheesh Kumar Mk; Lin Li; Valsaraj Kt; Jianlin Hu

doi:10.1016/j.envpol.2022.119468

Integrated process analysis retrieval of changes in ground-level ozone and fine particulate matter during the COVID-19 outbreak in the coastal city of Kannur, India

Environ Pollut. 2022 Aug 15:307:119468. doi: 10.1016/j.envpol.2022.119468. Epub 2022 May 16.

Authors

Fei Ye¹, Dipesh Rupakheti¹, Lin Huang¹, Nishanth T², Satheesh Kumar Mk³, Lin Li¹, Valsaraj Kt⁴, Jianlin Hu⁵

Affiliations

¹ Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science & Technology, Nanjing, 210044, China.
² Department of Physics, Sree Krishna College Guruvayur, Kerala, 680102, India.
³ Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Karnataka, 576104, India.
⁴ Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA, 70803, USA.
⁵ Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science & Technology, Nanjing, 210044, China. Electronic address: jianlinhu@nuist.edu.cn.

Abstract

The Community Multi-Scale Air Quality (CMAQ) model was applied to evaluate the air quality in the coastal city of Kannur, India, during the 2020 COVID-19 lockdown. From the Pre1 (March 1-24, 2020) period to the Lock (March 25-April 19, 2020) and Tri (April 20-May 9, 2020) periods, the Kerala state government gradually imposed a strict lockdown policy. Both the simulations and observations showed a decline in the PM_2.5 concentrations and an enhancement in the O₃ concentrations during the Lock and Tri periods compared with that in the Pre1 period. Integrated process rate (IPR) analysis was employed to isolate the contributions of the individual atmospheric processes. The results revealed that the vertical transport from the upper layers dominated the surface O₃ formation, comprising 89.4%, 83.1%, and 88.9% of the O₃ sources during the Pre1, Lock, and Tri periods, respectively. Photochemistry contributed negatively to the O₃ concentrations at the surface layer. Compared with the Pre1 period, the O₃ enhancement during the Lock period was primarily attributable to the lower negative contribution of photochemistry and the lower O₃ removal rate by horizontal transport. During the Tri period, a slower consumption of O₃ by gas-phase chemistry and a stronger vertical import from the upper layers to the surface accounted for the increase in O₃. Emission and aerosol processes constituted the major positive contributions to the net surface PM_2.5, accounting for a total of 48.7%, 38.4%, and 42.5% of PM_2.5 sources during the Pre1, Lock, and Tri periods, respectively. The decreases in the PM_2.5 concentrations during the Lock and Tri periods were primarily explained by the weaker PM_2.5 production from emission and aerosol processes. The increased vertical transport rate of PM_2.5 from the surface layer to the upper layers was also a reason for the decrease in the PM_2.5 during the Lock periods.

Keywords: CMAQ; COVID-19 lockdown; O(3); PM(2.5); Process analysis.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Air Pollution* / analysis
COVID-19*
Communicable Disease Control
Disease Outbreaks
Environmental Monitoring / methods
Humans
India
Ozone* / analysis
Particulate Matter / analysis

Substances

Aerosols
Air Pollutants
Particulate Matter
Ozone