Aeroplanes are grounded, people are locked indoors, and factories are shut.
But as humans slow down the pace of economic activity to try and prevent , the natural world, it seems, is breathing a sigh of relief.
Air pollution over regions in China and Europe has improved as a result.
Over China, NASA and the European Space Agency (ESA) spotted a significant decrease in pollution between January and February.
Satellite imagery showed a reduction in the levels of nitrogen dioxide - caused by cars, power plants and industrial facilities - than is usual during that period, when the Lunar New Year often leads to a drop-off in emissions.
Source: NASA Earth Observatory
The agencies compared the change before the lockdown in Wuhan on 23 January and during the quarantine between 10-25 February, and found concentrations of the gas fell significantly. The reduction was first noticed in Wuhan but eventually spread across the country.
The reduction was estimated at between 10-30 per cent.
For NASA researchers, the change was startling.
“This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event,” NASA air quality researcher Fei Liu said in a statement.
A man wears a face mask in Beijing, China, on 13 February. Source: Getty Images
Some experts say the reduction in pollution may have even saved more lives than the death toll caused by the deadly virus in China.
According to rough calculations done by Stanford University scientist Marshall Burke, the reduction in air pollution may have helped saved the lives of 77,000 people in China under the age of five, and over 70.
“Given the huge amount of evidence that breathing dirty air contributes heavily to premature mortality, a natural - if admittedly strange - question is whether the lives saved from this reduction in pollution caused by economic disruption from COVID-19 exceeds the death toll from the virus itself,” he wrote in the .
“Even under very conservative assumptions, I think the answer is a clear ‘yes’.”
Children wearing face masks play at a park in Beijing on 20 March. Source: AFP/Getty Images
The reductions for China, though, were short-lived. Nitrogen dioxide levels are increasing again as life slowly returns to normal for some.
Reductions in nitrogen dioxide have also been noticed across Europe, but particularly northern Italy, where the lockdown began on 9 March.
The European Space Agency noted the changes between 1 January until 11 March using the Copernicus Sentinel-5P satellite.
Josef Aschbacher, director of Earth observation programmes at the ESA, said while weather factors should be taken into consideration, the reduction was quite a surprise.
“The drop in Italy, especially over the Po Valley, has been quite significant and is certainly to a large extent linked to a lockdown of Italy due to the COVID-19 outbreak,” he told SBS News.
“However, I believe that the pollution levels will further drop in the next days and weeks. Also, other countries are now imposing drastic measures, and we will see reduced air pollution (e.g. NO2 levels) as a result.”
Cloudy and clear sky cover Iran's capital Tehran on 2 March as air pollution levels drop due to coronavirus. Source: Anadolu/Getty Images
Climate scientist Michael Mann said we’re likely to see a drop in global emissions because of the economic slowdown across the world.
“We expect that a decrease in global domestic product leads to a decrease in carbon emissions,” he said.
“This is very difficult to predict because, for one, we don’t know precisely what the impact on the economy will be yet.
“But I expect a bigger impact than the great recession of the late 2000s/early 2010s and a drop, perhaps several per cent, in global carbon emissions.”
Australian climate scientist Robyn Schofield said Australia is also likely to see a drop in emissions, although it’s too early to predict by how much.
Dr Schofield, who specialises in air pollution studies, said we can expect to see the reduction in urban areas due to the limitations on transport and industry.
“We’ll certainly see greenhouse gas emissions reductions from the transport sector and industry sectors so we will see a large greenhouse gas reduction as well,” she said.
'Opportunity to act'
Both Dr Schofield and Mr Mann believe the dramatic changes show how the world can mobilise to act on climate change.
“There are absolutely lessons to be learnt that socially we can change and we can change quite quickly and it can have great health benefits,” Dr Schofield said.
Mr Mann said the real longer-term crisis was climate change itself.
“And ironically our response to a different crisis - the coronavirus pandemic - indicates that it is possible for us to change our ways, but only when there are governmental efforts to support behavioural change, which we have seen with coronavirus and need to see, now, with climate change,” he said.
Mr Aschbacher said the changes will only temporarily improve air quality and a reduction of CO2 emissions for a couple of weeks or months and will have a small impact in the long-term.
“What it may do, however, is change the perception of people to make them realise that human activity has a large impact on the planet's environment and might lead to a partial re-thinking in several domains.”
Mr Aschbacher is based in Rome and has seen the human tragedy of the virus unfold in Italy.
“We all wish that the coronavirus pandemic will subside as quickly as possible and not cause many more casualties.
“We shall be careful not to justify improved air quality at the cost of human lives caused by the coronavirus.”
If you believe you may have contracted the virus, call your doctor, don’t visit, or contact the national Coronavirus Health Information Hotline on 1800 020 080.
If you are struggling to breathe or experiencing a medical emergency, call 000.
NASA Earth Observatory images by Joshua Stevens, using modified Copernicus Sentinel 5P data processed by the European Space Agency.