Epidemic shutdowns have reduced air pollution – but with a problem

Last April, as People around the world are protected in place against the Covid-19 pandemic, Indian Express Newspaper Post a picture Spreading on Twitter, a deep, hazy blue sky appears over Uttar Pradesh, the most populous state in northern India. Above the garden trellis, the angular white peaks of the Himalayas were seen on the horizon like whipped hard meringues. Pawan Gupta, a senior scientist with the University Space Research Consortium at NASA’s Marshall Space Flight Center, says friends and family in India told him the peaks had not been visible for decades. The reason is simple: before the epidemic closed, the air was filled with smog.

Gupta studies air pollution in India and, like many other scientists, has been studying how lockdowns have reduced emissions over urban areas. “This is a natural experience for a lot of us,” says Gupta. A natural experience that proves one thing above all – the air quality can improve, and quickly, too.

at The study was published This March at Sustainable cities and societyGupta and colleagues focused on three months – from March to May 2020 – when travel, construction, and industry were restricted outside of medical facilities. They compared air pollution measures in six major cities – Bengaluru, Chennai, Delhi, Calcutta, Mumbai and Pune – to the same period in the previous three years. Using satellite imaging, they found a 42 to 60 percent reduction in particulate matter and a 46 to 61 percent decrease in nitrogen dioxide (NO).2), And it is a potentially toxic air pollutant.

Fine particlesThe scientific term for soot includes soil, dust, smoke, and allergens. Very small particles can make their way into people’s lungs and bloodstream, making bronchitis worse, causing heart attacks, and even speeding up death. No2 It is caused by the combustion of fossil fuels, and can exacerbate asthma and increase the likelihood of developing a respiratory infection.

Gupta’s fellow Christoph Keeler, a senior scientist at the same Research Society within NASA, has been monitoring urban air pollution as well. to Keeler’s Special StudyPosted on Atmospheric Chemistry and Physics In March of this year, he created a basic computer model for what global NO is2 Emissions were in 2020 without any shutdowns. He then used surface measurements to track actual emissions in cities around the world, including Melbourne, Taipei and Rio de Janeiro. Its results showed NO worldwide2 Decreased by nearly 20 percent, and 50 of the 61 cities analyzed showed a decrease of between 20 and 50 percent. Notably, Wuhan, China, showed a decrease of 60 percent; For New York City, it was 45 percent.

“One of the lessons we can learn from the pandemic is that there is still great potential for reducing nitrogen oxide2 Keeler says. “What we see clearly in urban environments is that there is still a lot of NO2 This is man-made. We can really reduce it a little bit. “

Other recent studies have echoed the same findings. Marco Carnevale Meno is a PhD student in engineering at the University of Pavia, Italy, 22Not checked2 Concentrations in three European cities. It was found to have decreased by 80.8% in London, 79.8% in Paris, and 42.4% in Milan between March and May, which is linked to reduced traffic due to travel restrictions. In Santiago, Chile, researchers studied urban air pollution During those same three months and compared to the same period during the previous three years. They also found that the average concentrations of particulate matter and nitrogen dioxide decreased. 22In Portugal, researchers found that NO2 By 41% and particles by 18% During the period from March to May compared to the past five years. Researchers studied in the United Kingdom No2 The data from January to June 2020 found, again, that concentrations decreased anywhere from 32 to 50 percent during the lockdown and gradually increased as road traffic returned.

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