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Open AccessArticle

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

1
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
2
ClimaCell Inc., 280 Summer Street Floor 8, Boston, MA 02210, USA
3
School of Engineering, Westlake University, Hangzhou 310024, China
4
Institute of Advanced Technology, Westlake Institute for Advanced Study, Hangzhou 310024, China
5
School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
6
Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China
7
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; https://doi.org/10.3390/atmos11040433
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
    Link: https://doi.org/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.

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