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Air pollution returning to pre-COVID levels

on 08 April 2021

In early 2020, data from satellites were used to show a decline in air pollution coinciding with nationwide lockdowns put in place to stop the spread of COVID-19. One year later, as lockdown restrictions loosen in some countries and regular activity resumes, nitrogen dioxide levels are bouncing back to pre-COVID levels.

On 23 January 2020, the world saw the first coronavirus lockdown come into force in Wuhan, China in an effort to stop the spread of the illness. This lockdown set the precedent for similar measures in other cities across the country, putting a halt to daily activities including industry and traffic. Factories and other industries were shut down and people were confined to their homes. Similar measures were then put in place worldwide in the following weeks and months.

As a result, a significant reduction in air pollutants across China was detected by satellites. This included reduced emissions of nitrogen dioxide – a gas which pollutes the air mainly as a result of traffic and the combustion of fossil fuel in industrial processes.

Now, more than one year later, as restrictions have eased, the average level of air pollutants has rebounded and is on the rise again. The maps below show the monthly average concentrations of nitrogen dioxide, derived from data from the Copernicus Sentinel-5P satellite, in the central and eastern portions of China in February 2019, February 2020 and February 2021. The map shows the fluctuation in levels between the three periods, with dark red indicating high concentrations of nitrogen dioxide.

2021 04 Covid POllution Image B

More details here.

Image credit: contains modified Copernicus Sentinel data (2019-21), processed by ESA, CC BY-SA 3.0 IGO