And it seems that the lockdown imposed by the pandemic of Covid-19 not only served to slow the spread of the new coronavirus, but also resulted in a significant drop in air pollution by ozone, a chemical released by automobiles, factories, power plants and refineries. 

Second NASA estimates, ozone air pollution between May and June 2020 fell by 2%, largely due to gas emission reductions in Asia and the Americas. Although it seems little, according to Science Alert, experts say that the reduction was on a global scale and that, without the stoppage caused by the pandemic, the rate would take at least 15 years to be achieved.


“I was really surprised at how big the impact on global ozone was,” said Jessica Neu, who researches the chemical composition of the atmosphere at the Jet Propulsion Laboratory at NASA

Ozone: not all bad

Ozone is not all bad, but a balance is needed for us to enjoy its benefits. Ozone molecules in the stratosphere form the ozone layer that protects our planet from the Sun's radiation.

In the tropospheric air – the layer closest to the Earth – it affects the quality of the air by retaining heat and ends up contributing to global warming, in addition to working as a pollutant due to chemical reactions caused by combustion processes in industries and vehicles. Exposure beyond what is recommended can irritate the lungs and increase the risk of people dying from cardiovascular or respiratory disease, meaning it can be fatal.

Pandemic: Lockdown led to ozone air pollution drop, says NASA. Image: Shutterstock/Evgenil Panov
Pandemic: Lockdown led to drop in air pollution by ozone, says NASA. Image: Shutterstock/Evgenil Panov

However, the reactions depend not only on this, but also on the climate and the presence of other pollutants and chemicals. In some scenarios, a drop in nitrogen oxides can increase ozone pollution, meaning that it is difficult to predict the process and what the reaction might lead to.

Therefore, the stoppage caused by the pandemic was seen by researchers as an “opportunity scenario” to discover what would happen to the atmosphere if there was a rapid and large reduction in human activity with our pollutants. For specialists, the result opens paths of knowledge for the creation of more effective environmental policies.

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Drop in more pollutants

In addition to ozone, the team found that the lockdown also helped in the drop in the amount of nitrogen emitted. In April and May, for example, global emissions fell by at least 15% and the drop was seen mainly in nations that had the tightest locks.

In China, for example, a 50% drop in pollutants was recorded after the lockdown at the beginning of the year. In the United States, Europe, the Middle East and West Asia, the quarantine led to a drop of 18% to 25% between the same months (April and May).

The satellites, from which the researchers collected the survey data, showed that the drop in ozone emission cleared the air over an area of ​​up to 10 kilometers (6 miles). For experts, being able to measure improvements and worsening in the climate and air is extremely important, as it directly affects the health of society.

“I was very happy that our analysis system was able to capture the detailed changes in emissions around the world,” said atmospheric scientist Kazuyuki Miyazaki of NASA's Jet Propulsion Laboratory. "The challenging and unprecedented nature of this work is a testament to the improvements in satellite monitoring in the service of society's needs."

According to World Health Organization (WHO), air pollution kills about 7 million people each year and is considered a silent pandemic.

The results of the study show the global capacity to curb negative impacts on the environment and improve the atmosphere and human health. Unfortunately, without the good practices needed to keep emissions from falling, they will grow again once the world returns to normal.

Published in Science Advances, click here to access the full study.

Source: Science Alert

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