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Friday, 20 March 2020

COVID-19: pandemic has reduced air pollution in several countries


As the spread of the SARS-CoV-2 coronavirus continues to expand, the pandemic has begun to show positive trends worldwide. This is particularly the case of air pollution. According to the latest observation results from the ESA Copernicus satellite, the containment measures would have made it possible to reduce carbon dioxide and nitrogen dioxide pollution significantly. And according to researcher Mashall Burke, the number of lives indirectly saved by this reduction in pollution could far exceed the human losses due to the virus.

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.



Pollution reduction in China: lives saved would exceed losses due to virus

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.

Loss of average life expectancy according to different causes of death for the year 2015. Air pollution arrives at the top of the podium with approximately 3 years of life expectancy lost, before smoking. Credits: Jos Lelieveld et al. 2020

"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."

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.

A net reduction in nitrogen dioxide pollution in Italy

"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.

This ESA video shows the reduction of nitrogen dioxide emissions in Italy:



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