India April 2019 and India April 2020ESA
Concentrations of sulfur dioxide in polluted areas in India have decreased by up to 40 percent between April 2019 and April 2020.
The data was compiled by the Copernicus Sentinel-5P satellite, from the European Union Copernicus program, and translated into a map that shows the drop in concentrations across the country during the COVID-19 pandemic.
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The scourge of sulfur dioxide
Last year, a Greenpeace report named India the world's largest emitter of anthropogenic sulfur dioxide — a large contributor to air pollution. Sulfur dioxide can cause health problems for populations, it can harm ecosystems, and is also a precursor to acid rain.
Though some sulfur dioxide is produced naturally in the environment, such as through volcanic activity, a substantial amount is released into the atmosphere by human activity — predominantly from the burning of fossil fuels.
The last decade has seen a sharp increase in sulfur dioxide emissions in India, leading to haze problems across large parts of the country. However, the new data shows that levels have dropped considerably following the beginning of India's lockdown, which started on March 25, 2020, an ESA press release explains.
The maps above show the average sulfur dioxide concentrations in April 2019, compared with the same month a year later. The darker shades of red and purple depict greater concentrations of the gas in the atmosphere.
EU's Copernicus Program
The analysis was produced using data from the Tropomi instrument on the Copernicus Sentinel-5P satellite, part of the EU's Copernicus program, which is collecting data on the climate so as to guide policy aimed at improving environmental conditions worldwide.
The findings correlate with data from NASA that has shown air pollution drop over China following the start of lockdown restrictions in the country. Cleaner air is one of the few positives stories in world news in 2020.