With full cities and countries under lockdown due to the coronavirus pandemic, there have been reports from around the world of reduced air pollution.
Researchers from China, Italy and the USA have all reported a significant drop in emissions over areas that have been affected by the Covid-19 strain of coronavirus. Here’s why.
Where has air pollution declined?
China was the first nation to report a decline in pollution due to the coronavirus outbreak. Climate website Carbon Brief reported that the country’s CO2 emissions had dropped by up to a quarter over the four week period leading up to 1 March. This represents a 200 million tonne reduction, which is about half of the UK’s annual emissions.
In the two weeks in February during which the city of Wuhan and other parts of China were under quarantine, the cloud of nitrogen dioxide above the country seemed to evaporate.
Fei Liu, one of NASA’s air quality researchers, said, "This is the first time I have seen such a dramatic dropoff over such a wide area for a specific event."
Over the course of the year, experts believe this will likely lead to a one per cent fall in China’s overall emissions.
Stanford University air quality expert Marshall Burke estimated that the reduced emissions may “have saved the lives of 4,000 kids under five and 73,000 adults over 70.”
The country with the most confirmed cases outside of China, Italy has also seen a noticeable decline in air pollution since the nation went under lockdown to try and curb the virus’ spread. Pictures from Venice have also shown the canals, which are often very murky, running clear.
Air pollution satellite, Copernicus Sentinel-5P, noted a reduction in nitrogen dioxide, carbon monoxide, methane and various other substances.
Researchers in New York have reported that early results suggest that carbon monoxide levels there have decreased by up to 50 per cent. They also reported a five to 10 per cent reduction in CO2 in the air above the city as well.
According to the BBC, scientists are predicting that global CO2 emissions could hit their lowest point since 2008 this May.
Why has air pollution declined?
The reports from New York have suggested that a decrease in traffic has been the main cause of the drop in pollution, with traffic levels in the city down 35 per cent from the previous year. With schools closed and many people working from home or living in full self-isolation, the coronavirus outbreak has caused a dramatic reduction in the number of cars in use across the world.
Similarly, Venice’s canals have seen a downturn in the amount of boat traffic upon them as all non-essential travel is restricted.Many industrial operations have also been reduced due to the coronavirus. A report from Lauri Myllyvirta at the Centre for Research on Energy and Clean Air suggested that this played a large role in China’s reduced emissions.
Claus Zehner, who manages the Copernicus Sentinel-5P satellite which reported Italy’s reduced emissions believed that both factors were at play there.
“Although there could be slight variations in the data due to cloud cover and changing weather, we are very confident that the reduction in emissions that we can see coincides with the lockdown in Italy causing less traffic and industrial activities,” he said.