Bengaluru: Around 1.24 lakh Indians every year – that’s how many deaths the Modi government could be responsible for after it decided to exempt many coal-fired thermal power plants from installing technology to limit sulphur emissions in July last year.A study published on May 4 shows that eliminating sulphur emissions from thermal power plants can decrease concentrations of fine particulate matter (a major air pollutant) across the country drastically – enough to prevent around 1.24 lakh deaths annually. People living in states such as Chhattisgarh and Odisha would benefit most from these reductions, as will people belonging to the Other Backward Classes (OBC) and Scheduled Castes (SC) and Tribes (ST). Per the study, installing flue-gas desulphurisation systems or FGDs and other sulphur emission control measures in power plants would be more cost-effective than the healthcare costs incurred otherwise.Energy and atmospheric scientists told The Wire that the Union environment ministry should immediately reverse its notification exempting around 80% of coal-fired thermal power plants across the country from installing FGDs.Only India recorded a rise in sulphur emissionsThe notification drew ire in July 2025 for several reasons. One was that the decision went against the government’s mandate in 2015 that all thermal power plants should implement FDGs in their units – a decision backed by science that shows that sulphur emission-limiting technologies are extremely important in reducing air pollution and linked health impacts.Another was that a few days after the notification, the Ministry defended its decision. On July 14, it released a statement claiming that media reports had “grossly misinterpreted” its notification and that the rationale was based on “detailed scientific studies” and “extensive consultations with stakeholders and research institutions”.Now, a detailed study of sulphur dioxide emission levels from thermal power plants across India shows that limiting emissions from such plants across the country would bring Indians significant benefits. For this, scientists at IIT Delhi’s Centre for Atmospheric Sciences and Air Quality Research Division in the Environment and Climate Change Canada (a department under the government of Canada) analysed a range of data: sulphur emissions in India derived from a global satellite-based emissions catalogue, premature deaths caused by exposure to fine particulate matter (PM2.5) as given by the Global Burden of Disease study, and economic and demographic data from India’s National Family Health Survey.The study found that globally, sulphur dioxide emissions decreased continuously from 2005 to 2021 (from 44.11 to 19.37 thousand kilotons or Kt per yr), and witnessed a sharp drop after 2013. But in India, sulphur dioxide emissions increased during this time. It rose from 2.36 to 5.05 thousand Kt per year from 2005 to 2021. This then increased by around 30% in 2023. This is because of higher coal consumption and operating coal-fired power plants without sulphur dioxide emission controls such as FGDs, said Sunil Dahiya, Founder and Lead Analyst at Delhi-based think tank EnviroCatalysts. “China generates way more power than India, even from coal. But because they have FGDs, they are able to control their emissions,” he said.One of the major reasons that Chinese cities were able to reduce pollution levels aggressively is because they acted on both power plants and industries burning coal, ensuring that all these facilities have FGDs implemented, Dahiya commented. Huge health benefitsPer the study, India’s main sulphur emission hotspots are in the “industrialised central-east regions, particularly in Chhattisgarh and Orissa”. The study also found that completely mitigating sulphur emissions from coal-fired thermal power plants could decrease ambient fine particulate matter concentrations by around 0.3 to 12 µg/m3 across India.This is a very “significant” reduction that the study which uses “fair, robust scientific methodology” has found, commented Dahiya, who was not involved in the study. For context as to how significant this reduction will be, consider the permissible limits of fine particulate matter as per the National Ambient Air Quality Standards (NAAQS) set by the Central Pollution Control Board (CPCB) in 2009: 40 µg/m3 annually, and 60 µg/m3 in a 24-hour-span.Completely eliminating sulphur emissions across India could also decrease very high concentrations of ambient fine particulate matter by around 8 µg/m3 in eastern and central states. The states that would gain most from this would be Chhattisgarh and Orissa, followed by Maharashtra, Madhya Pradesh and other industrialized areas in central India. Even south Indian states such as Tamil Nadu, Karnataka and Kerala would benefit from this, per the study.The health benefits that follow will be enormous.Per the study, completely eliminating sulphur dioxide emissions from coal-fired power plants can help India prevent around 1,24,564 premature deaths every year. This includes an estimated 14,777 deaths from cardiovascular disease and 8,476 deaths from respiratory causes due to exposure to fine particulate matter.So will installing FGDs – which are known to reduce around 95% of sulphur emissions from power plants – prevent these deaths?“Yes, we can say that confidently,” Dahiya told The Wire. “Because there is always an uncertainty margin for such numbers, and this margin is about 5% here. So we can clearly say that if we implement FGD norms in all power plants in India, including the ones which were exempted last year, India could save approximately 1.24 lakh people annually.”Installing FGDs will definitely prevent these 1.24 lakh deaths, agreed Manoj Kumar, analyst with independent international NGO Centre for Research on Energy and Clean Air (CREA).Even these may be underestimationsIn fact, the estimated health benefits will be higher because India plans to add another 87 gigawatts of coal-fired thermal power plant capacity by 2025, Kumar told The Wire, citing a December 2025 government press release. “The estimated health impacts might increase approx to 1.5 fold…As a result, health benefits outweigh FGD installation costs,” he commented.Across economic groups, the study estimates that the middle class and the poor will derive larger benefits from PM2.5 reductions, as will wealthier sections in urban areas if India eliminates sulphur dioxide emissions across all states. Among caste-based subgroups, the more vulnerable sections – the OBCs, as well as the SCs and STs, will benefit more with the better air quality than people in the General category. But the study’s numbers could well be underestimations of the impacts of sulphur emissions from coal-fired thermal power plants.Almost all the limitations that the scientists have pointed out in their own study suggest that their methods could in fact be underestimating impacts – such as pollution concentrations or air quality benefits – of limiting sulphur emissions in coal-fired power plants. For instance, one limitation they list is that the study does not take into account small emission sources of sulphur emissions, and that this can potentially underestimate pollutant concentrations inferred in this study. Another is that due to lack of fine geographical data on air pollution levels, the study used the same pollutant exposures for different sub-populations within buffer zones of 2 to 5 km – which assumes that the impacts of people living within this zone from thermal power plants experience the same pollution levels. Science, however, shows that the impacts on air quality are highest closest to power plants. “Such coarser data and mixed neighbourhoods of sub-populations may underestimate disparities in air quality benefits at different geographic scales,” the study says.According to the study, there is an “urgent need” to mitigate sulphur dioxide emissions from coal-fired power plants in India.“The comprehensive evaluation of air quality and health benefits in our study, along with recent benefit-cost evidence in India, highlights that individuals’ willingness to pay additional out-of-pocket expenses through government investments in FGD installations and other emission control measures would be more cost-effective than the healthcare costs otherwise needed to prevent related health impacts,” the study noted, adding that delays in installing FGDs could “worsen air quality” and “related health impacts in the foreseeable future”.Same centre, two conflicting studies?Incidentally, the same Centre (IIT Delhi’s Centre for Atmospheric Sciences) whose scientists led and co-authored the new study, published a non-peer reviewed report in 2024 that gave contrasting recommendations. It said that “the urgency of FGD installation across India must be reassessed” because the impact of sulphur dioxide emissions on ambient particulate matter levels is “relatively minor” and that installing FGDs in thermal power plant units to limit sulphur emissions would have an “insignificant impact” on lowering particulate matter levels. The report, commissioned by the government-run Central Electricity Authority, came to these conclusions based on a one-year, three-phase study of sulphur dioxide levels across ten cities including Delhi, Nagpur and Kolkata. “Our study indicates that installing FGD systems with an 87.5% SO₂ removal efficiency in all coal-based TPPs across India would lead to a maximum reduction in PM2.5 concentrations of up to 4.56% (2.89 µg/m³) and PM10 concentrations of up to 3.21% (3.15 µg/m³). This reveals that SO₂ emissions from TPPs contribute relatively little to ambient air PM2.5 and PM10 mass concentrations in the surveyed cities and seasons. Consequently, there would be only a marginal improvement (5%) in particulate matter air quality even after eliminating allSO₂ emissions from TPPs,” it said. This 2024 report was also one of the references that the Union environment ministry cited to justify its decision to exempt around 80% of coal-fired thermal power plants across the country from installing FGDs in July 2025.The report regarding the recent notification issued by the Ministry regarding the applicability of Sulphur Dioxide norms in respect of Thermal power Plants has been grossly misinterpreted.The norms of Sulphur Dioxide emissions from Thermal Power Plants notified on 11th July… pic.twitter.com/0aKpNaEXgy— MoEF&CC (@moefcc) July 14, 2025The Wire contacted one of the authors of the report, professor Sagnik Dey of the CAS, who is also an author on the new study, about why there was such disparity in the findings of both reports. He responded that the report did not say there were no impacts (of sulphur dioxide emissions on particulate matter levels) and that it had shown that impacts vary from city to city. While the report only looked at the baseline data for six cities and linked modelling studies, the new study examined all of India; the new study also shows small relative contributions in the Delhi NCR area, but large relative contributions elsewhere, he said.“Both studies are consistent,” he said. But some experts are not convinced. A scientist who did not want to be named pointed out that this is why peer review is important. The same group’s findings show an entirely different outcome now because only good methodology and scientific robustness will stand in the global scientific community – unlike when scientists have to file reports for the government, the expert said.Govt should reverse exemptionOther experts told The Wire that it was time for the Union environment ministry to reverse its July 2025 notification that exempts around 80% of thermal power plants from installing FGDs. “Last year, the policy dilution happened without considering any health impact study,” Kumar told The Wire. “Now we have strong evidence that shows health benefits of installing FGD. So yes, MOEF[CC] must consider this study and reverse their decision.”Dahiya said that the study shows that the cost of implementing FGD norms is way lower than the health costs that could be incurred otherwise – “a good enough reason for this investment to be done”.Moreover, FGD implementation had progressed in the years from 2015 to 2025 and a majority of power plants – almost all those owned by central sector undertakings such as the NTPC and DVC – had made significant progress in installing the FGDs; some had even operationalised them while others were nearing completion, Dahiya added. “If we don’t use the investment into these FGDs, it is as good as throwing away all that money invested and not gaining any benefits from it. That is why all those power plants that have installed FGDs or are nearing completion should immediately be given urgent timelines so that they start operating these immediately and the remaining ones should also follow,” he added.