From scientific evidence to excuses: NEERI and NIAS reports undercut FGD policy with contradictions – Centre for Research on Energy and Clean Air

India’s coal-fired thermal power plants are a major source of deadly air pollution, and the solution is neither new nor complicated. Flue gas desulfurization (FGD) is a proven technology that removes sulfur dioxide (SO₂), a harmful pollutant released when coal-fired power plants are operated. SO₂ turns into fine particulate matter (PM2.5) that enters our lungs and causes various diseases, killing millions every year.

Yet power plants across the country continue to stall the installation of FGDs, ignoring public health, government deadlines, and basic environmental responsibility. What’s worse, studies by institutions like NEERI, NIAS, and IIT Delhi (2022 and 2024) are now being selectively used to justify this inaction, citing low SO₂ levels or small CO₂ increases to argue that FGDs are unnecessary. These arguments simply don’t hold up.

The claim made by the NEERI that ambient SO₂ levels are already low is highly misleading. The air quality monitoring stations (CAAQMS) don’t capture the real impact of power plant pollution because they don’t track whether emissions drift upwind or downwind, and they certainly don’t account for chemical reactions that convert SO₂ into other pollutants like PM2.5. Just because the station reading is low ambient SO₂ doesn’t mean the plant is not polluting. The real picture comes from stack emissions, which show that SO₂ levels are always dangerously above the legal limit.

It is important to note that SO₂ emission norms and the requirement to install FGDs are based on stack emissions, not on ambient SO₂ levels. Using low ambient readings to argue against FGD is not just scientifically wrong, it completely misleads how pollution control works.

The NEERI report, often cited to downplay the importance of FGD, itself acknowledges that “if a flue gas desulfurization technique is installed to reduce sulphur emissions from thermal power stations, it will reduce a part of it, and the overall reduction in ambient air PM will be at most 20 µg/m³” (Section 5.4.4, Page 5.10). For example, reducing PM2.5 levels by 20 µg/m³ in India’s most polluted city, where annual averages are around 100 µg/m³, would mean achieving a 20% reduction from a single control measure. It is alarming to see NEERI completely ignoring its own key finding and basing its recommendation on ambient SO₂ concentrations.

Another report by IIT Delhi in 2022 highlighted that “with the implementation of FGD in the Vindhyachal TPP, we can expect to see a decrease in the monthly mean surface concentrations of sulfate aerosols in the range of 10–15% of the climatological values at certain places as far as 100 km from the location of this TPP,” and further noted that “significant decreases in sulfate aerosol concentrations are also observed as far as 200 km from the TPP” (Page 175). This clearly demonstrates the long-range, transboundary impact of coal-fired thermal power plants. Based on these findings, the report recommended a phased national rollout of FGDs across all coal-based power stations.

However, in their 2024 report, contradicting their earlier findings that identified thermal power plants as a national pollution source, IIT Delhi narrowed the scope to just six cities and reversed its stance. The newer IIT Delhi report recommended halting FGD installations in plants that have yet to adopt them, despite the fact that 92% of plants still lack FGDs. This shift was justified again by citing low ambient SO₂ levels and limited impact, overlooking the secondary particle formation and impacts starting from the vicinity of the plant, all the way to broader regional impacts.

More alarmingly, it is very worrying that the number of people who may suffer or die is not being acknowledged or addressed in any of the reports. Scientific articles showed that coal-fired power plants led to 47,000 deaths in 2014, 62,000 deaths in 2017, and 78,000 deaths in 2018. One needs to note that India is planning to build an addition of 80 to 100 GW of coal power plants and it is very likely that the health impacts would be much worse than what is being estimated now.

Another frequently cited argument attempts to divert attention by claiming that the installation of FGD systems leads to increased CO₂ emissions. According to a report by the NIAS, FGD implementation is projected to add approximately 23 million tonnes of CO₂ by 2030, which is just 0.9% of India’s total CO₂ emissions in 2020. This additional emission is comparable to the output of a coal-based power plant with over 3 GW capacity. The Ministry of Power, dated 20 January 2023, instructed that old and inefficient coal power plants should not be retired. However, this move could lead to significantly higher CO₂ emissions, especially since the Central Electricity Authority (CEA) had earlier planned to shut down around 47 GW of such capacity by 2027.

The irony lies in the fact that while this marginal CO₂ increase by FGD is criticised, plans to build an additional 80 to 100 GW of coal capacity, which would result in far greater CO₂ emissions, are not questioned with the same urgency.

Another excuse is that installing FGDs causes long plant shutdowns of up to 45 days. But NTPC RTI data shows that most FGDs were fitted during regular maintenance, with no additional shutdown period. Moreover, NTPC has already installed FGDs in plants with a combined capacity of 20 GW, and an additional 47 GW is currently under construction. The average time between the FGD award date and commissioning date was approximately 38 months.

Meanwhile, the latest studies from IIT Delhi and IIT Bombay make it crystal clear: power plants are a leading cause of India’s air pollution. The power sector contributes up to 12% of PM2.5 during winter, and is responsible for 16% of cross-boundary urban pollution. That’s on par with the vehicle sector, where the country went through a national initiative to switch to BSVI many years before – however, the coal-fired power sector, despite wasting 10 years, now wants almost all plants barring NTPC and wants a free pass from any regulation.

Since emissions from coal-fired power plants have long-range impacts, affecting air quality at the national level, FGD installation should be mandatory across India, regardless of plant location. FGDs are a critical, life-saving tool that India should have deployed years ago. Every delay means more lives lost, more children breathing toxic air, and more communities suffering from preventable disease.

It is clear that by contradicting their own earlier reports and relying on misleading scientific arguments, much of the power sector barring NTPC appears intent on delaying FGD installation. This approach prioritises profit over public health, placing the burden of inaction on the very people it is meant to serve: Indian citizens.

Download the article in PDF

List of key scientific studies estimating health impacts of power plants in India

-End-