Breathe easy: 40% drop in Sulphur Dioxide concentration in air across India

ESA’s observations show SO2 concentration in Delhi fell when coal-fired power plants and industries shut down for the lockdown. (Source: Shutterstock)
Sulphur Dioxide (SO2) concentration, an air pollutant released by the burning of fossil fuels, reduced across India by almost 40 per cent when the country was shut down for more than two months to contain the coronavirus pandemic, data released by the European Space Agency (ESA) shows.

ESA’s observations show SO2 concentration in Delhi fell when coal-fired power plants and industries shut down for the lockdown, which started on March 24 and now has been eased off. While power plants across the country ceased entirely, some in the states of Odisha, Jharkhand, and Chhattisgarh maintained a substantial level of activity.

The observations are significant as India was in 2019 named the world’s largest emitter of SO2. India’s emissions have increased in the last 10 years, leading to haze and poor air quality in cities including national capital New Delhi.

Coal-based power plants and oil refineries are responsible for two-thirds of the anthropogenic SO2 emissions. “The country ranking shows India as the top emitter of SO2 in the world, contributing more than 15 per cent of the global anthropogenic SO2 emissions,” said Greenpeace in a 2019 report.

"We have experienced a reduction in Sulphur dioxide, however, this is temporary and it's not going to benefit in the long run. We should not forget that because of the drastic fall in consumption in the industrial and commercial categories, the power demand has also gone down during the lockdown. This reduction in SO2 could be achieved in the long run with cleaner energy sources," said Avinash Chanchal, Senior Climate and Energy Campaigner for Greenpeace India.

Power plants and Sulphur Dioxide concentration as observed by ESA satellite. (Source: ESA)

ESA’s observations come days after the Supreme Court rejected a request by power companies to extend the deadline to install equipment to cut emissions by two years to 2024. The apex court in its June order said, “We are not inclined to allow the prayer made in the application.”

India has a phased plan for plants to comply with emissions standards, which involve installing Flue Gas Desulphurization (FGD) units that cut emissions of Sulphur Dioxide. More than half of India’s coal-fired power plants ordered to retrofit equipment to curb Sulphur Dioxide emissions are set to miss the deadlines which go up to the end of 2022.

The Ministry of Environment, Forest and Climate Change introduced SO2 emission limits for coal-fired power plants in December 2015, but the deadline for the installation of the FGDs in power plants have been shifted from 2017 to 2022. "It is high time to take strict steps to put pressure on thermal power plants so that they can implement the new emission standards," Avinash said.

Delhi has had several bouts of smog filled air leading straining the heathcare situation.

Power plants in and around New Delhi have already missed a deadline to install emission control systems. Last month the Central government also removed a provision requiring the washing of coal, saying the process caused more pollution.

While India continues its dependency on coal-based power plants, countries like China and the United States of America have been able to reduce SO2 emissions rapidly. While the US has switched to clean energy sources, China drastically improved the emission standards and enforced SO2 control across the mainland.

The ESA's observations were produced using data from the Tropomi instrument onboard the Copernicus Sentinel-5P satellite. The Sentinels are a fleet of dedicated EU-owned satellites central to the European Union's Copernicus Environmental Programme. 

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