Impact of coronavirus pandemic is the “largest scale experiment ever” into global air quality

The coronavirus pandemic is the “largest scale experiment ever” into global air quality, according to Professor Paul Monks, Professor of Atmospheric Chemistry and Earth Observation Science at the University of Leicester, after new satellite images from the European Space Agency (ESA) are released showing drastic differences between air pollution before and after the outbreak.

Levels of nitrogen dioxide have significantly dropped after a reduction in industrial and transport emissions occurred, owing to the pandemic.

Measurements from ESA’s Sentinel-5P satellite show that during the past six weeks, levels of nitrogen dioxide (NO2) over cities and industrial areas in Asia and Europe are lower than in the same period last year.

Professor Monks said: “We are now, inadvertently, conducting the largest-scale experiment ever seen. This might give us some hope from something so clearly terrible - we can see what could be achieved in terms of a low pollution future. Road traffic accounts for about up to 80% of nitrogen oxide emissions in cities the UK. It seems entirely probable that a reduction in air pollution will be beneficial to people in susceptible categories, for example some asthma sufferers.

“What I think will come out of this is a realisation - because we are forced to - that there is considerable potential to change working practices and lifestyles. This challenges us in the future to think, do we really need to drive our car or burn a fuel for that.”

Nitrogen dioxide is produced from car engines, power plants and other industrial processes and is thought to exacerbate respiratory illnesses such as asthma. While not a greenhouse gas itself, the pollutant originates from the same activities and industrial sectors that are responsible for a large share of the world’s carbon emissions and that drive global heating.

Roadside monitors in the UK already show significantly reduced levels of pollution at hotspots such as Marylebone in London.

The city of Wuhan, which has been on lockdown since late January, has seen one of the largest drops in pollution levels. The city of 11 million people serves as a major transportation hub and is home to hundreds of factories supplying car parts and other hardware to global supply chains. According to Nasa, nitrogen dioxide levels across eastern and central China have been 10-30% lower than normal.

NO2 levels also dropped in South Korea, which has long struggled with high emissions from its large fleet of coal-fired power plants but also from nearby industrial facilities in China.

The changes over northern Italy are particularly striking because smoke from a dense cluster of factories tends to get trapped against the Alps at the end of the Po Valley, making this one of Western Europe’s pollution hotspots.