US space agency National Aeronautics and Space Administration (NASA) reported based on its satellite data that air pollution over northern India has decreased by a 20-year-low. The Indian government placed lockdown on March 25, restricting 1.3 billion citizens from going outside to reduce the spread of the coronavirus. The nation-wide lockdown decreased activity of factories and severely reduced car, bus, truck and airplane traffic.
Every year, the human-made sources of anthropogenic aerosols cause unhealthy levels of air-pollution. Aerosols means tiny solid and liquid particles released into the air reducing the visibility and damaging the human lungs and heart.
Pawan Gupta, a Universities Space Research Association (USRA) scientist at NASA’s Marshall Space Flight Center, said “We knew we would see changes in atmospheric composition in many places during the lockdown,”
“But I have never seen aerosol values so low in the Indo-Gangetic Plain at this time of year,” added Gupta.
Alice G Wells, the Acting Assistant Secretary of State for South and Central Asia tweeted, “These images from NASA were taken each spring starting in 2016 and show a 20-year low in airborne particle levels over India. When India and the world are ready to work and travel again, let’s not forget that collaborative action can result in cleaner air.”
Every year at this time, which is early spring, human activities generate the majority of aerosols. Coal-fired power plants, motor vehicles, and other industrial sources release carbon-rich particles, nitrates and sulfates. But the 2020 lockdown has reduced those human-made emission sources.
The heavy rainfall around March 27, helped clear the air of aerosol in a wide range of area. Mr. Gupta said it was difficult to observe a change in the pollution level within a few days. “We saw an aerosol decrease in the first week of the shutdown, but that was due to a combination of rain and the lockdown,” said Gupta.
“After the rainfall, I was really impressed that aerosol levels didn’t go up and return to normal. We saw a gradual decrease, and things have been staying at the level we might expect without anthropogenic emissions,” he added.