Film shows ‘breathtaking’ emissions reductions during lockdown

Timelapse satellite imagery from the University of Leicester reveals startling reductions in air pollution.

Dan Potts, who is studying for a Master of Physics, worked with Professor Hartmut Boesch and Dr David Moore of the National Centre for Earth Observation at the University to plot data from the Tropospheric Monitoring Instrument (TROPOMI).

Dan, 22, said: “I’ve been looking at nitrogen dioxide emissions from power stations. After lockdowns started happening around the world due to the coronavirus, I adapted my code to start producing plots like these, to see the affect that these lockdowns were having on air pollution. The stark reduction in emissions over a few short weeks is breath-taking.”

Dan’s film shows levels of nitrogen dioxide (NO2) from December 2019 to the end of March 2020 over eastern China, northern Italy and India; each map is a ten-day average centred on the date shown. Nitrogen dioxide is produced from car engines, power plants and other industrial processes and is thought to exacerbate respiratory illnesses such as asthma.

The Italian video shows an expected reduction over Christmas and New Year before a rise which then dips suddenly in March, while the video for China shows a drop in NO2 levels at the end of January, which only start to recover from early March. In India a gradual decrease in emissions is seen until a sharp drop around 27 March, coinciding with a nationwide lockdown.

Professor John Remedios, Professor of Earth Observation Science and Director of the National Centre for Earth Observation, said: “Dan’s work has clearly shown us how air quality pollutants can be changed across large numbers of countries by human actions we would have thought not possible a year ago.”

“Returns to work will no doubt be reflected in poorer air quality but we will have learnt that changes in our behaviours do make it possible to have large-scale impacts.”

Launched just over two years ago aboard the Copernicus Sentinel-5 Precursor satellite, TROPOMI measures ultraviolet, visible and infrared wavelengths with a resolution of 7km by 3.5 km.

TROPOMI is a collaboration between ESA, the European Commission and the Netherlands Space Office.