The COVID-19 lockdown induced changes of SO2 pollution in its Human-made global hotspots

Sulphur dioxide (SO₂) is a hazardous air pollutant, which is mostly emitted from burning of fossil fuels, and has an adverse impact on the human health and ecosystem functioning. The COVID-19 natural anthropause (lockdown) provides a great opportunity to understand the changes in SO₂ pollution across the globe, as there was a temporary standstill for most human activities. Therefore, we analyse the changes in global SO₂ pollution during lockdown compared to pre-lockdown and identify its hotspots driven by human activities using satellite measurements, reanalysis data and emission inventory. We observe a decline in SO₂ pollution of about 2.21 % in its global average, −21.05 % in Indo-Gangatic Plain, −16 % in East China, −7.67 % in East United States of America, −3.99 % in Western Europe and −3.85 % in Middle East owing to the halt in human activities such as industrial and transport operations, as found from the emissions inventory. There are point and aerial hotspots of SO₂ pollution across the globe (e.g. cities or industrial units), which also show a decrease (20–30 %) in SO₂ pollution during the anthropause. Fossil fuel burning in thermal power plants is a major source of SO₂ pollution, and it has declined notably (1–12 %) during the lockdown in the major coal consuming countries such as the United States, China, Japan, Canada, Brazil, Australia, France, Germany, Spain, Italy and the United Kingdom. Therefore, lockdown provides a clear understanding of global human-driven hotspots of SO₂ pollution and their changes, which would help us to make better and effective air pollution mitigation strategies.