Delhi pollution: Blame thermal plants, not just farmers for toxic air

A research by the Centre for Research on Energy and Clean Air reveals that thermal power plants in the national capital region release 16 times more air pollutants than stubble burning

Are farmers solely to be blamed for the poisonous air in Delhi? This long-held belief that the stubble burning in Punjab and Haryana during the October-November months is the primary cause behind Delhi’s hazardous air quality, has been challenged by the Centre for Research on Energy and Clean Air in its new study. The study reveals that in the age-old agriculture vs industry debate, it’s the industries that are to be blamed more for causing health problems to the residents of Delhi-NCR.

 

The research by the Centre for Research on Energy and Clean Air (CREA) reveals that thermal power plants in the national capital region (NCR) release 16 times more air pollutants than stubble burning. The study notes that these plants emit 16 times the 17.8 kilotonnes of pollutants generated from burning 8.9 million tonnes of paddy straw.

 

 

CREA’s analysis, as cited by The Times of India, shows that coal-fired thermal power plants in NCR emitted 281 kilotonnes of sulphur dioxide (SO₂) between June 2022 and May 2023.

 

India remains the largest emitter of SO₂ globally, accounting for over 20 per cent of human-caused emissions worldwide. This is largely attributed to the country’s dependence on coal for energy. In 2023, India’s SO₂ emissions from power generation reached 6,807 kilotonnes, far exceeding those of Turkey (2,206 kilotonnes) and Indonesia (2,017 kilotonnes).

 

Worsening air quality in Delhi

 

These findings coincide with worsening air quality in Delhi, where the Air Quality Index (AQI) reached 441 on November 17, placing the city in the ‘severe’ pollution category and making it the second-most polluted city in India. At 4 pm the same day, the city’s 24-hour AQI stood at 441. On the preceding Saturday, the AQI was recorded at 417.

 

As per the Central Pollution Control Board (CPCB), an AQI in the ‘severe’ range can harm healthy individuals and have serious impacts on those with pre-existing health conditions.

 

Difference in pollutants emitted by stubble burning and thermal plants

 

The study underscores the disproportionate impact of emissions from thermal power plants compared to paddy straw burning in Punjab and Haryana. While thermal power plants in NCR release 281 kilotonnes of SO₂ annually, burning 8.9 million tonnes of paddy straw emits just 17.8 kilotonnes. This demonstrates the persistent and large-scale pollution caused by power plants throughout the year, in contrast to the seasonal impact of stubble burning.

 

The report highlights the need for stricter emission controls on thermal power plants, noting that these facilities often benefit from lenient enforcement and repeated deadline extensions for installing flue gas desulfurization (FGD) systems. In contrast, farmers face penalties and strict monitoring during stubble-burning seasons. Adopting FGD technology more rapidly could lower NCR emissions to 93 kilotonnes annually—a 67 per cent reduction, according to the study.

 

Meanwhile, the Centre’s Decision Support System for Air Quality Management identified vehicular emissions as contributing 15.8 per cent of Delhi’s pollution on Sunday, while stubble burning accounted for 25 per cent on Saturday. The CPCB noted that PM2.5 was the primary pollutant. These fine particles, measuring 2.5 micrometres or less, can penetrate the lungs and enter the bloodstream, posing severe health risks.

 

Measures not taken by thermal plants

 

Within a 300-km radius of Delhi, there are 11 coal-based thermal power plants. Additionally, the Goindwal Sahib Power Plant in Punjab, located just outside this radius, is also considered when evaluating the impact of thermal power plants around Delhi.

 

According to CREA, of the 12 thermal power plants, only the Mahatma Gandhi thermal power station (TPS) in Haryana has fully implemented Flue Gas Desulfurization (FGD) technology, while the Dadri thermal power plant in Uttar Pradesh has partially installed it. 

 

The remaining 10 coal-based plants have missed four deadlines—December 2017, December 2019, March 2021, and December 2022. The latest deadline for four of these plants is now December 2024, while for the other six, it is December 2026. In 2015, the Centre issued notices to all coal-based thermal power plants in this zone, directing them to install FGD technology.

 

How does SO₂ spread and form PM2.5?

 

Sulphur dioxide contributes to the formation of fine particulate matter (PM2.5), which can travel vast distances and exacerbate air quality issues. Coal-fired power plants remain a significant source of SO₂ emissions. Chimney plumes from these plants can be carried long distances by wind or trapped near the ground due to weather conditions like atmospheric inversion.

 

In the atmosphere, SO₂ can condense on existing particles or form new particles, resulting in sulphate aerosols — a major component of PM2.5. This mechanism is similar to the process occurring during stubble burning, which also releases sulphur dioxide.

 

Health impacts of Sulphur Dioxide in air

 

Exposure to SO₂ has several adverse health effects, particularly on the respiratory system:

 

>It can cause wheezing, shortness of breath, and chest tightness, especially during physical activity, as rapid breathing enables the gas to reach deeper into the lungs.

 

>Prolonged exposure to high levels can lead to chronic respiratory symptoms and diminished lung function.

 

>Even short-term exposure to high concentrations can exacerbate asthma symptoms and pose challenges for outdoor activities.

 

>Vulnerable groups, including children, the elderly, and individuals with asthma, face higher risks of hospitalisation or emergency medical care due to SO₂ exposure.