{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,6]],"date-time":"2026-02-06T04:18:08Z","timestamp":1770351488799,"version":"3.49.0"},"reference-count":54,"publisher":"MDPI AG","issue":"24","license":[{"start":{"date-parts":[[2022,12,15]],"date-time":"2022-12-15T00:00:00Z","timestamp":1671062400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["21976031"],"award-info":[{"award-number":["21976031"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["42075097"],"award-info":[{"award-number":["42075097"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["22176037"],"award-info":[{"award-number":["22176037"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>An unprecedented city-wide lockdown took place in Shanghai from April to May 2022 to curb the spread of COVID-19, which caused socio-economic disruption but a significant reduction of anthropogenic emissions in this metropolis. However, the ground-based monitoring data showed that the concentration of ozone (O3) remained at a high level. This study applied Tropospheric Monitoring Instrument (TROPOMI) observations to examine changes in tropospheric vertical column density (VCD) of nitrogen dioxide (NO2) and formaldehyde (HCHO), which are precursors of O3. Compared with the same period in 2019\u20132021, VCDs of NO2 and HCHO decreased respectively by ~50% and ~20%. Multiple regression analysis showed that the lockdown effect played a dominant role in this dramatic decline rather than meteorological impacts. Using the exponentially-modified Gaussian method, this study quantified nitrogen oxides (NOX) emission in Shanghai as 32.60 mol\/s with a decrease of 50\u201380%, which was mainly contributed by the transportation and industrial sectors. The significant reduction of NOX emission in Shanghai is much higher than that of volatile organic compounds (VOCs), which led to dramatic changes in formaldehyde-to-nitrogen dioxide ratio (HCHO\/NO2, FNR). Thus, when enforcing regulation on NOx emission control in the future, coordinately reducing VOCs emission should be implemented to mitigate urban O3 pollution.<\/jats:p>","DOI":"10.3390\/rs14246344","type":"journal-article","created":{"date-parts":[[2022,12,15]],"date-time":"2022-12-15T03:01:51Z","timestamp":1671073311000},"page":"6344","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["Ozone Pollution of Megacity Shanghai during City-Wide Lockdown Assessed Using TROPOMI Observations of NO2 and HCHO"],"prefix":"10.3390","volume":"14","author":[{"given":"Ruibin","family":"Xue","sequence":"first","affiliation":[{"name":"Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China"}]},{"given":"Shanshan","family":"Wang","sequence":"additional","affiliation":[{"name":"Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China"},{"name":"Institute of Eco-Chongming (IEC), Shanghai 202162, China"}]},{"given":"Sanbao","family":"Zhang","sequence":"additional","affiliation":[{"name":"Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China"}]},{"given":"Jingfang","family":"Zhan","sequence":"additional","affiliation":[{"name":"College of Foreign Languages and Literature, Fudan University, Shanghai 200433, China"}]},{"given":"Jian","family":"Zhu","sequence":"additional","affiliation":[{"name":"Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China"}]},{"given":"Chuanqi","family":"Gu","sequence":"additional","affiliation":[{"name":"Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China"}]},{"given":"Bin","family":"Zhou","sequence":"additional","affiliation":[{"name":"Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China"},{"name":"Institute of Eco-Chongming (IEC), Shanghai 202162, China"},{"name":"Zhuhai Fudan Innovation Institute, Zhuhai 519000, China"},{"name":"Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, China"}]}],"member":"1968","published-online":{"date-parts":[[2022,12,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1582","DOI":"10.1016\/j.scitotenv.2016.10.081","article-title":"Ozone pollution in China: A review of concentrations, meteorological influences, chemical precursors, and effects","volume":"575","author":"Wang","year":"2017","journal-title":"Sci. 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