Pandemic blockades reduced air pollution, but with a catch

Last April, as people around the world protected against the Covid-19 pandemic, Indian Express newspaper He posted a photo that went viral on Twitter, showing a rather foggy deep blue sky showing Uttar Pradesh, the most populous state in northern India. On a garden trellis, the angular, white peaks of the Himalayan mountains could be seen on the horizon like a hard, rigid meringue. Pawan Gupta, a senior scientist at NASA’s Marshall Space Flight Center University Space Research Association, says friends and relatives in India have told him that the peaks have not been so spectacular for decades. The reason for this is simple: before the pandemic closed, the air was full of smoke.

Gupta is studying air pollution in India, and like many other scientists, he has been studying how blockages have reduced emissions over urban areas. “It’s a natural experiment for many of us,” Gupta says. Above all, the natural experiment proved one thing: air quality can be improved, and it can be done quite quickly.

In one published research this March Sustainable Cities and Societies, Gupta and his colleagues focused on three months (March to May 2020) when travel, construction, and industry outside medical facilities were limited. Air pollution metrics were compared to six metropolitan areas — Bengaluru, Chennai, Delhi, Kolkata, Mumbai and Pune — over the same period over the previous three years. Using satellite imagery, particles were reduced by 42-60 percent and nitrogen dioxide (NO) by 46-61 percent.₂), a potentially toxic air pollutant.

Particlesthe scientific term for soot includes soil, dust, smoke, and allergens. Very tiny particles can enter people’s lungs and bloodstream, worsening bronchitis, causing heart attacks and speeding up death. NO₂ it is caused by the burning of fossil fuels, which can exacerbate asthma and lead to respiratory infections.

Gupta’s colleague Christoph Keller, a senior scientist at NASA’s same research association, also looked at the city’s air pollution. For Keller’s study itself, published in Chemistry and Atmospheric Physics this March, he created the basis for a computer model of what is a global NO₂ the spills would be in 2020 without any blockages. He then used surface measurements in cities around the world, including emissions from Melbourne, Taipei and Rio de Janeiro. His results showed NO worldwide₂ a decrease of almost 20%, and 50 of the 61 cities studied had reductions of between 20 and 50 per cent. Notable is Wuhan (China) a 60 percent reduction; In New York, it was 45 percent.

“One of the lessons we can learn from the pandemic is that there is still a lot of potential to NOT go down₂ concentrations, ”says Keller.“ What we see clearly in urban environments is that there is still NOT much₂ that is man-made, which we can really reduce considerably. “

Recent research has echoed the same results. Marco Carnevale Miino, PhD student in engineering from the University of Pavia, Italy, ₂₂examine NO₂ concentrations in three European cities. It fell by 80.8 per cent in London, 79.8 per cent in Paris and 42.4 per cent in Milan between March and May, when it was related to the drop in traffic caused by travel restrictions. In Santiago, Chile, researchers studied urban air pollution during these three months and compared with the same period in the previous three years. In addition, they found that the average concentrations of particles and NO2 decreased. ₂₂In Portugal, researchers NO₂ it fell by 41 per cent and particles by 18 per cent from March to May compared to the last five years. It was studied by researchers in the UK NO₂ Data from January to June 2020 have again shown that concentrations have been reduced from 32% to 50% during blockades and have gradually increased with the return of road traffic.