Nitrogen dioxide concentrations drop amid coronavirus spread

Strict measures implemented in China to slow the spread of coronavirus have led to a dramatic reduction in nitrogen dioxide concentrations. The measures include closing factories and clearing streets.

As news of the coronavirus broke out in the Hubei province, China, in late December 2019, stricter measures were put in place. As a result, by late January, factories were closed and streets were cleared as Chinese authorities had ceased daily activities to stop the spread of the illness, according to a statement from the European Space Agency (ESA).

This led to the dramatic reduction in nitrogen dioxide concentrations – those released by power plants, industrial facilities and vehicles – in all major Chinese cities between late-January and February.

The Copernicus Atmosphere Monitoring Service (CAMS) observed a decrease of fine particulate matter – one of the most important air pollutants – in February 2020 compared to the previous three years. By combining satellite observations with detailed computer models of the atmosphere, their studies indicated a reduction of around 20-30 per cent in surface particulate matter over large parts of China.

An ESA animation, using data from the Copernicus Sentinel-5P satellite, shows the nitrogen dioxide concentrations from 20 December 2019 until 16 March 2020 – using a 10-day moving average. The drop in concentrations in late-January is visible, coinciding with the nationwide quarantine, and from the beginning of March, the nitrogen dioxide levels have begun to increase.

Claus Zehner, ESA’s Copernicus Sentinel-5P mission manager, commented: “We can certainly attribute a part of the nitrogen dioxide concentration reduction to the impact of the coronavirus. We currently see around a 40% reduction over Chinese cities, however these are just rough estimates, as weather also has an impact on emissions.

“We are conducting a detailed scientific analysis which will soon provide more insights and quantified results in the following weeks and months.”

The Copernicus Sentinel-5 Precursor mission, also known as Sentinel-5P, is dedicated to monitoring air pollution by measuring a multitude of trace gases as well as aerosols – all of which affect the air we breathe.

Image credit: Lei Han, flickr/Creative Commons

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