European Space Agency satellite imagery reveals NO₂ Emissions have disappeared across China and Italy as a direct result of COVID-19 lockdowns.
The COVID-19 pandemic is getting more overwhelming by the day, with increasing lockdowns, a death toll of more than 7,000 people across the world, and a direct hit to the global economy.
But if there's a sliver of good news, it's about how the spread of the new coronavirus has been decreasing air pollution, and possibly even saving lives in the process.
Back on March 8, Stanford University environmental resource economist Marshall Burke did some back-of-the-envelope calculations about the recent air pollution drop over parts of China and potential lives saved, posting it on a global food, environment and economic dynamics blog, G-FEED.
The situation has continued to unfold since then, so those numbers won't stay current for long; but according to Burke, even conservatively, it's very likely that the lives saved locally from the reduction in pollution exceed COVID-19 deaths in China.
"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," Burke writes.
"Even under very conservative assumptions, I think the answer is a clear 'yes'."
The two months of pollution reduction, Burke calculates, has probably saved the lives of 4,000 children under 5 and 73,000 adults over 70 in China. That's significantly more than the current global death toll from the virus itself.
Although this might seem a little surprising, it's something we've known about for quite a long time. Earlier this month, research suggested that air pollution costs us three years, on average, off our global life expectancy.
"It is remarkable that both the number of deaths and the loss in life expectancy from air pollution rival the effect of tobacco smoking and are much higher than other causes of death," physicist Jos Lelieveld from the Cyprus Institute in Nicosia stated at the time.
"Air pollution exceeds malaria as a global cause of premature death by a factor of 19; it exceeds violence by a factor of 16, HIV/AIDS by a factor of 9, alcohol by a factor of 45, and drug abuse by a factor of 60."
So, it's well established that air pollution really does kill.
But Burke's analysis was just using data from China, and was completed before there was more information about how COVID-19 has affected the rest of the world.
With the second largest number of cases occurring in Italy, and the country putting in place strict quarantine measures, satellite data over northern Italy have now shown a large drop in air pollution - specifically nitrogen dioxide, a gas mainly emitted by cars, trucks, power plants and some industrial plants.
Using the Tropomi instrument on the Copernicus Sentinel-5P satellite, images taken from 1 January to 11 March 2020 showed nitrogen dioxide dropping dramatically.
"The decline in nitrogen dioxide emissions over the Po Valley in northern Italy is particularly evident," explains Claus Zehner, ESA's Copernicus Sentinel-5P mission manager.
"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 lock-down in Italy causing less traffic and industrial activities."
For now, we don't have peer-reviewed studies measuring the true health impact reduced emissions will bring, but given what we know about the dangers of widespread air pollution, it's likely that there will be a direct benefit in the shape of fewer pollution-related deaths.
Even such a tiny silver lining can hardly make up for the devastation of the COVID-19 pandemic. But these preliminary numbers demonstrate that this global health disaster is an opportunity to assess - which aspects of modern life are absolutely necessary, and what positive changes might be possible if we change our habits on a global scale.
The Emissions Impact of Coronavirus Lockdowns
There’s a high chance you’re reading this while practicing social distancing, or while your corner of the world is under some type of advised or enforced lockdown.
While these are necessary measures to contain the spread of the COVID-19 pandemic, such economic interruption is unprecedented in many ways—resulting in some surprising side effects.
The Evidence is in NO₂ Emissions
Nitrogen dioxide (NO₂) emissions, a major air pollutant, are closely linked to factory output and vehicles operating on the road.
As both industry and transport come to a halt during this pandemic, NO₂ emissions can be a good indicator of global economic activity—and the changes are visible from space.
These images from the Centre for Research on Energy and Clean Air (CREA), as well as satellite footage from NASA and the European Space Agency (ESA), show a drastic decline in NO₂ emissions over recent months, particularly across Italy and China.
NO₂ Emissions Across Italy
In Italy, the number of active COVID-19 cases has surpassed China (including the death toll). Amid emergency actions to lock down the entire nation, everything from schools and shops, to restaurants and even some churches, are closed.
Italy is also an industrial hub, with the sector accounting for nearly 24% of GDP. With many Italians urged to work from home if possible, visible economic activity has dropped considerably.
This 10-day moving average animation (from January 1st—March 11th, 2020) of nitrogen dioxide emissions across Europe clearly demonstrates how the drop in Italy’s economic activity has impacted the environment.
That’s not all: a drop in boat traffic also means that Venice’s canals are clear for the time being, as small fish have begun inhabiting the waterways again. Experts are cautious to note that this does not necessarily mean the water quality is better.
NO₂ Emissions Across China
The emissions changes above China are possibly even more obvious to the eye. China is the world’s most important manufacturing hub and a significant contributor to greenhouse gases globally. But in the month following Lunar New Year (a week-long festival in early February), satellite imagery painted a different picture.
