This datasets contains the top-down NOx emission data during Jan 1 - Mar 12, 2020, derived in the paper NOx emission reduction and recovery during COVID-19 in East China (https://www.mdpi.com/2073-4433/11/4/433). The top-down NOx emission changes can be used as a measure to assess the socioeconomic activity changes due to COVID-19 control measures. Data Description: regional_emission_changes_TableS1.xlsx: The derived NOx emission changes in China at regional (East China), provincial, and city (Wuhan) levels. regional_emission_timeseries.zip: The timeseries plots of NOx emission changes in the mentioned regions NO2_VCD_NOx_emission.nc: This contains data used to derive the top-down NOx emissions (at 0.05 degree resolution): NO2 data from TROPOMI and WRF-GC; NOx emissions from MEIC emission inventory. How to Cite: Please cite both the Zenodo dataset and the paper (https://www.mdpi.com/2073-4433/11/4/433, 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.). Contact: If you have questions, please contact the corresponding authors Drs. Ruixiong Zhang (zhangruixiong@gmail.com) and Yuzhong Zhang (zhangyuzhong@westlake.edu.cn). Paper Abstract: 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 – January 22nd, 2020), P2 (January 23rd, Wuhan lockdown – February 9th, 2020), and P3 (February 10th, back-to-work day – 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 has 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.