Abstract
During the COVID‐19 outbreak that took place in early 2020, the economic activities in China were drastically reduced and accompanied by a strong reduction in the emission of primary air pollutants. On the basis of measurements made at the monitoring stations operated by the China National Environmental Monitoring Center, we quantify the reduction in surface PM2.5, NO2, CO, and SO2 concentrations in northern China during the lockdown, which started on 23 January 2020. We find that, on the average, the levels of surface PM2.5 and NO2 have decreased by approximately 35% and 60%, respectively, between the period 1 and 22 January 2020 and the period 23 January and 29 February 2020. At the same time, the mean ozone concentration has increased by a factor 1.5–2. In urban area of Wuhan, where drastic measures were adopted to limit the spread of the coronavirus, similar changes in the concentrations of PM2.5, NO2, and ozone are found.
Highlights
During the COVID‐19 outbreak of February and March 2020 that disrupted dramatically the economy in China, emissions of primary pollutants due to transportation and industrial activity, including nitrogen oxides (NOx) and carbon monoxide (CO), were severely reduced in this region of the world
On the basis of measurements made at the monitoring stations operated by the China National Environmental Monitoring Center, we quantify the reduction in surface PM2.5, NO2, CO, and SO2 concentrations in northern China during the lockdown, which started on 23 January 2020
When the averages of the data gathered by more than 800 stations before and during the lockdown are compared, we find that the mean levels of PM2.5 and NO2 in northern China have decreased by approximately (29 ± 22%) and (53 ± 10%), respectively
Summary
During the COVID‐19 outbreak of February and March 2020 that disrupted dramatically the economy in China, emissions of primary pollutants due to transportation and industrial activity, including nitrogen oxides (NOx) and carbon monoxide (CO), were severely reduced in this region of the world. We analyze the situation in two urban areas in which the economic activity has been severely reduced after 23 January 2020. Several limitations in this comparison between the time periods should be stressed. CO is a product of residential combustion and power generation, while NOx is emitted primarily by industrial activity and transportation It contributes to the photochemical formation of ozone during summertime, while, in polluted areas, it titrates ozone during the winter months.
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