A recent study by researchers from IIT Delhi, published in the journal Nature, indicates that India could avert approximately 124,564 deaths annually by completely eliminating sulfur dioxide (SO₂) emissions from coal-fired power plants (CFPPs).
This research represents one of the initial detailed efforts to assess the impact of SO₂ emissions from CFPPs, not only on ambient SO₂ concentrations but also on the generation of secondary fine particulate matter, commonly referred to as PM2.5.
The findings suggest that reducing these emissions could lead to a decrease in annual PM2.5 exposure by between 0.3 and 12 micrograms per cubic meter, as well as a reduction in ambient SO₂ levels ranging from 0.1 to 13.6 parts per billion in various states.
CFPPs release SO₂ which interacts with atmospheric components to create secondary inorganic aerosols, including sulfates, nitrates, and ammonium. These pollutants contribute to PM2.5, which is associated with cardiovascular and respiratory health issues.
Debajit Sarkar, a co-author of the study from IIT Delhi, noted, “Numerous existing studies on source apportionment indicate that the energy sector is a primary contributor to air pollution. Together with the household sector, thermal power plants rank among the top sources of pollution. Therefore, we aimed to quantify the exact impact of this sector.”
The researchers employed air pollution models along with satellite data regarding SO₂ emissions from CFPPs. They also utilized the Global Burden of Disease framework, which evaluates health impacts across different demographics, to estimate the number of deaths that could be prevented from pollution-related health issues, including cardiovascular and respiratory diseases. Furthermore, they correlated air quality data with the National Family Health Survey-5 data, conducted from 2019 to 2021, to analyze potential benefits across various gender, caste, and income groups.
The analysis revealed that completely eliminating SO₂ emissions from CFPPs could prevent 14,777 cardiovascular deaths and 8,476 respiratory deaths each year, in addition to reducing overall mortality rates.
Maharashtra, Tamil Nadu, and Karnataka were projected to experience the highest number of avoidable deaths due to significant population exposure to pollution. Conversely, Chhattisgarh and Odisha were expected to see the most substantial improvements in air quality, given their numerous coal power-related pollution hotspots.
The research also highlighted that the health benefits would not be uniformly distributed. Individuals from Other Backward Classes, Scheduled Castes, and Scheduled Tribes, along with lower-income and middle-income groups, are anticipated to experience greater air quality improvements compared to wealthier demographics. According to the researchers, this underscores the importance of addressing SO₂ emissions as both an air quality and environmental equity issue.
This study emerges amidst ongoing discussions regarding the implementation of flue gas desulfurization (FGD) systems in CFPPs. FGD technology is designed to remove SO₂ from the exhaust gases of coal-fired power plants and industrial boilers, thereby reducing acid rain and air pollution.
Opponents of FGD installation often cite the relatively low sulfur content of Indian coal, which makes the technology costly. However, the study contends that the health benefits associated with reduced emissions are likely to surpass the expenses of installing emission-control technologies.
Manoj Kumar, a researcher at the Centre for Research on Energy and Clean Air, emphasized the significance of these findings, noting that previous estimates had not fully captured the health impacts related to SO₂. “These observations are crucial, especially considering that the costs associated with saving lives will outweigh the expenses related to FGD implementation,” he stated.
Kumar urged that these findings should be contextualized within the framework of the 2015 emissions standards for thermal plants and the subsequent delays in compliance. “These assessments were overlooked during the reversal of the 2015 policy. Most importantly, the study highlights the health impacts on vulnerable populations and the variation among states,” he added.
On December 7, 2015, the Union Ministry of Environment, Forest, and Climate Change introduced mandatory emissions standards for CFPPs, aimed at achieving significantly lower SO₂, nitrogen oxides, mercury, and particulate matter levels. However, on July 11, 2025, the Centre relaxed these standards, exempting approximately 79% of coal-fired units from the requirement to install FGD systems to control SO₂ emissions.
According to the IIT Delhi study, while global SO₂ emissions from CFPPs decreased between 2005 and 2021, India’s emissions increased during the same period. Satellite data indicated that India’s SO₂ emissions rose from 2.36 thousand kilotonnes per year in 2005 to 5.05 thousand kilotonnes in 2021, with an additional increase of about 30% projected for 2023.
The study advocates for stricter enforcement of SO₂ emission regulations, increased adoption of FGDs and related control technologies, and a focus on pollution hotspots. “India needs to rigorously implement SO₂ emission regulations, enhance the use of FGDs and pollution-control technology in power plants, and prioritize regions with high pollution levels. Additionally, transitioning to cleaner cooking fuels, promoting electric vehicles, and reducing stubble burning incidents are vital steps,” stated Sarkar.
Furthermore, the research highlighted that the implementation of SO₂ emission regulations in India remains “slow, localized, and uneven,” asserting that fully enforcing current limits could lead to a reduction of over 80% in SO₂ and PM2.5 emissions linked to coal power plants by 2030.
Sophiya Mathew is a Correspondent for The Indian Express, based in New Delhi.
