  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 20% larger than that
from recent years. We relate to 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.
