By Miki Perkins
For our free coronavirus pandemic coverage, learn more here.
No, dolphins and swans didn't return to the canals of Venice to swim in clear water as an unexpected side effect from the pandemic – these claims were shown to be fake.
But new research reveals it is true the grinding halt on global economic activity has had a remarkable effect on ground and atmospheric pollution.
Using satellite images and data from thousands of air quality stations, European researchers have found a 20 per cent decrease in air pollution – including ground-level nitrogen dioxide (usually caused by car pollution), ozone, and fine particulate matter (PM2.5) - during the first two weeks of lockdown in 27 countries around the world. You can have a look at their interactive here.
Even in Australia, which usually has very good air quality (aside from bushfire smoke pollution), you can see a small but visible decrease in nitrogen pollution, according to the new paper available through medRxiv, a site that carries scientific studies before they have been published. That means this study has not yet been subject to rigorous peer review, and its findings must be treated with caution.
The researchers also estimated there was a net total of 7400 premature deaths and 6600 paediatric asthma cases that were avoided during that fortnight in those 27 countries.
If the lockdown-induced reductions in pollutants were to continue for the whole of 2020, they estimated 780,000 premature deaths could be avoided globally.
“We by no means imply that global pandemics ... are beneficial to public health. But we suggest the current situation is a useful lens through which to view the global air pollution ‘pandemic’,” the researchers write.
Professor Zoran Ristovski, the acting head of the School of Earth and Atmospheric Sciences at the Queensland University of Technology, said the Australian satellite images seemed to show a reduction in nitrogen because of reduced traffic pollution, and also in the Hunter Valley and Gladstone regions, where coal-fired power stations are located.
“There are a lot of uncertainties in these types of studies but what we clearly see is a reduction, even after a short amount of time – just two weeks – in key pollutants,” Professor Ristovski said. "The reduction in PM2.5 particles [fine particles smaller than 2.5 microns] are especially important as we know they have the biggest health effect.”
Professor Ristovski said he was concerned that when the pandemic ends polluters will return to "business as usual", and that the significant economic fallout will mean environmental controls are neglected and air quality becomes worse.
A recent US study showed a correlation between air pollution and the number of coronavirus infections. In an analysis of 3000 counties in the United States, Harvard University researchers found higher levels of PM2.5 particles in the air were associated with higher death rates from the disease.
Long-term exposure to air pollution, including fine particulate matter, is estimated to cause more than 8 million deaths globally, each year. The main outdoor pollution sources include power generation, industry, traffic and residential energy use.