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NOx Emission Reduction and Recovery during COVID-19 in East China

School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
ClimaCell Inc., 280 Summer Street Floor 8, Boston, MA 02210, USA
School of Engineering, Westlake University, Hangzhou 310024, China
Institute of Advanced Technology, Westlake Institute for Advanced Study, Hangzhou 310024, China
School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China
School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
Authors to whom correspondence should be addressed.
Atmosphere 2020, 11(4), 433;
Received: 8 April 2020 / Revised: 20 April 2020 / Accepted: 21 April 2020 / Published: 24 April 2020
(This article belongs to the Special Issue Asian/Pacific Air Pollution and Environment)
Since its first confirmed case at the end of 2019, COVID-19 has become a global pandemic in three months with more than 1.4 million confirmed cases worldwide, as of early April 2020. Quantifying the changes of pollutant emissions due to COVID-19 and associated governmental control measures is crucial to understand its impacts on economy, air pollution, and society. We used the WRF-GC model and the tropospheric NO2 column observations retrieved by the TROPOMI instrument to derive the top-down NOx emission change estimation between the three periods: P1 (January 1st to January 22nd, 2020), P2 (January 23rd, Wuhan lockdown, to February 9th, 2020), and P3 (February 10th, back-to-work day, to March 12th, 2020). We found that NOx emissions in East China averaged during P2 decreased by 50% compared to those averaged during P1. The NOx emissions averaged during P3 increased by 26% compared to those during P2. Most provinces in East China gradually regained some of their NOx emissions after February 10, the official back-to-work day, but NOx emissions in most provinces have not yet to return to their previous levels in early January. NOx emissions in Wuhan, the first epicenter of COVID-19, had no sign of emission recovering by March 12. A few provinces, such as Zhejiang and Shanxi, have recovered fast, with their averaged NOx emissions during P3 almost back to pre-lockdown levels. View Full-Text
Keywords: COVID-19; NOx emission; air pollution; satellite retrieval; WRF-GC; GEOS-Chem COVID-19; NOx emission; air pollution; satellite retrieval; WRF-GC; GEOS-Chem
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  • Externally hosted supplementary file 1
    Doi: 10.5281/zenodo.3759985
    Description: The tropospheric NO2 data from TROPOMI and WRF-GC and MEIC NOx emission data used to derive top-down NOx emissions in this research.
MDPI and ACS Style

Zhang, R.; Zhang, Y.; Lin, H.; Feng, X.; Fu, T.-M.; Wang, Y. NOx Emission Reduction and Recovery during COVID-19 in East China. Atmosphere 2020, 11, 433.

AMA Style

Zhang R, Zhang Y, Lin H, Feng X, Fu T-M, Wang Y. NOx Emission Reduction and Recovery during COVID-19 in East China. Atmosphere. 2020; 11(4):433.

Chicago/Turabian Style

Zhang, Ruixiong, Yuzhong Zhang, Haipeng Lin, Xu Feng, Tzung-May Fu, and Yuhang Wang. 2020. "NOx Emission Reduction and Recovery during COVID-19 in East China" Atmosphere 11, no. 4: 433.

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