Abrupt decline in tropospheric nitrogen dioxide over China after the outbreak of COVID-19
This is the final version. Available on open access from the American Association for the Advancement of Science via the DOI in this record ; Data and materials availability: All satellite data used in this work is publicly available through NASA Goddard Earth Sciences Data and Information Services Center (https://disc.gsfc.nasa.gov/) and ESA Sentinel-5P Pre-Operations Data Hub (https://s5phub.copernicus.eu/). GMI model output and policy response data are available upon request from the authors as is code to process all data sets. All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data available from authors upon request. ; China's policy interventions to reduce the spread of the coronavirus disease 2019 have environmental and economic impacts. Tropospheric nitrogen dioxide indicates economic activities, as nitrogen dioxide is primarily emitted from fossil fuel consumption. Satellite measurements show a 48% drop in tropospheric nitrogen dioxide vertical column densities from the 20 days averaged before the 2020 Lunar New Year to the 20 days averaged after. This is 21% ± 5% larger than that from 2015–2019. We relate this reduction to two of the government's actions: the announcement of the first report in each province and the date of a province's lockdown. Both actions are associated with nearly the same magnitude of reductions. Our analysis offers insights into the unintended environmental and economic consequences through reduced economic activities. ; NASA