Air Pollution In India: Major Sources And Causes

India is one of the world's most polluted countries, with 1.4 billion people exposed to unhealthy levels of ambient particulate matter (PM2.5). The main sources of air pollution in India include industrial and vehicular emissions, construction dust and debris, thermal power plants, waste burning, and the use of wood and dung for cooking and heating. In 2019, India launched the National Clean Air Programme (NCAP) with a tentative target of reducing PM2.5 and PM10 concentrations by 20-30% by 2024.

Residential sources, including tobacco smoke and inefficient cooking stoves

Tobacco smoking has been linked to respiratory issues and lung cancer, and its joint impact with air pollution on mental health is an emerging area of research. Studies suggest that exposure to high levels of air pollution, particularly PM2.5, may be a risk factor for depression, and quitting smoking is recommended to reduce this risk.

Indoor air pollution from solid fuel use and inefficient cooking stoves is a critical issue in Indian households. In 2001, over 70% of households in India, rising to 90% in rural areas, relied on traditional solid fuels like wood, dung, and coal for cooking and heating. The burning of these fuels releases toxic pollutants, including fine particulate matter (PM2.5), and is a major risk factor for lung cancer and cardiovascular and respiratory diseases. Women and children, who typically spend more time indoors, are disproportionately affected, with children's carbon monoxide levels comparable to those from smoking cigarettes.

Improved cooking stoves, utilizing cleaner fuels and incorporating chimneys, have been introduced to address indoor air pollution. However, their effectiveness is limited by low uptake and irregular usage, with little evidence of improved health or reduced fuel usage over time.

To combat this, the Indian government has implemented initiatives like the Pradhan Mantri Ujjwala Yojna, promoting clean energy options like LPG for marginalized households. Additionally, large-scale ecological projects, such as the Great Green Wall of Aravalli, aim to mitigate pollution by planting native trees. These efforts are crucial steps towards improving India's air quality and reducing the health risks associated with residential air pollution sources.

Power emissions, especially from coal-burning

India's air pollution levels are among the highest in the world, posing a significant threat to the country's health and economy. One of the major contributors to this crisis is power emissions, particularly from coal-burning.

Coal-fired power plants are a significant source of air pollution in India. These plants emit harmful pollutants such as particulate matter (PM), sulfur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide, volatile organic compounds, and carbon dioxide. The health impacts of these emissions are severe, with an estimated 80,000 to 115,000 premature deaths in India attributed to coal-fired power plant emissions, accounting for 15-20% of the country's total premature deaths.

The International Energy Agency's Clean Coal Centre (IEACCC) has conducted studies highlighting the detrimental effects of coal burning on India's air quality. According to the IEACCC, coal-based thermal power stations without pollution control technology are responsible for over half of the country's SO2 emissions, 30% of NOx emissions, and about 20% of PM emissions, in addition to other man-made emissions. The delay in implementing the latest carbon capture storage technology and emission norms in these power plants exacerbates the problem.

To address the issue, the IEACCC has recommended the implementation of emission norms and the retirement of old coal-fired power stations to limit pollution and improve fleet efficiency. In 2015, India ratified emissions standards that included a mandate for flue-gas desulfurization (FGD) in power plants to promote clean energy and a healthier environment. It is estimated that full implementation of FGD could immediately reduce PM2.5 pollution from these plants by at least 50%.

In addition to the efforts mentioned above, India has also launched several initiatives to combat air pollution, such as the National Clean Air Programme, which aims to reduce PM2.5 and PM10 concentrations by 20%-30% by 2024. The country is also developing green ecological corridors, such as the Great Green Wall of Aravalli, to combat pollution and improve air quality.

While India has recognized the urgency of addressing air pollution, the challenge remains multi-sectoral and multi-jurisdictional, requiring close coordination and regional cooperation to implement effective strategies and improve the country's air quality.

Industrial emissions, including from unregulated small-scale industries

Industrial emissions are a major contributor to India's poor air quality. According to a study, 51% of India's air pollution comes from industrial sources, with industrial areas showing significantly higher levels of SOx and NOx emissions than residential areas.

There are 17 categories of industrial units that are required to have OCEMS (online continuous emissions/effluents monitoring systems) in place, including power plants, aluminium, zinc, and copper plants, as well as cement, distilleries, and fertiliser plants. Despite this, accessing data from these monitoring systems is challenging for the public. The data is often opaque or inaccessible, making it difficult for residents to understand the emissions levels and take necessary actions.

Small and medium-scale industries (SMEs) have also been identified as major sources of air pollution in India. These industries often rely on dirty coal as their primary fuel source, and inefficient technology leads to excessive coal burning, causing air pollution and greenhouse gas emissions. The regulatory agencies are overwhelmed due to limited resources, resulting in less monitoring of these smaller-scale industries.

To address these issues, organisations like CSE India are offering training programmes to build capacity and share best practices for emission control in the small and medium-scale sectors. Additionally, India's Parliament approved a law in August 2021 to establish the Commission of Air Quality Management in the National Capital Region and adjoining areas, recognising the need for coordinated action across jurisdictions to tackle air pollution effectively.

Vehicle emissions

India is the world's fourth-largest emitter of greenhouse gases, contributing 7% of global emissions. The country's rapid growth in vehicle registration and urbanisation have led to a significant increase in vehicle emissions, which are a major cause of air pollution in cities. Vehicular emissions are responsible for 27% of India's air pollution.

Vehicles emit pollutants such as carbon monoxide, hydrocarbons, nitrogen oxides, and particulate matter. These emissions are released into the atmosphere through the combustion of fossil fuels and the burning of biomass, such as wood and charcoal. In addition, traffic congestion and slow-moving vehicles emit even more pollutants, with cars emitting up to eight times more pollutants when travelling at speeds between 5 and 20 kilometres per hour compared to speeds between 55 and 70 kilometres per hour.

The problem of vehicle emissions is particularly acute in highly polluted cities like New Delhi, where vehicular emissions are the primary source of carbon monoxide. The transport sector accounts for a quarter of India's total emissions, with road transport contributing three-quarters of transport emissions. Furthermore, the use of adulterated fuel blends in taxis and auto-rickshaws increases emissions of harmful pollutants, exacerbating urban air pollution.

To address the issue of vehicle emissions, the Indian government has implemented Bharat Stage (BS) emission standards to regulate air pollutants from internal combustion engine vehicles. The government has also set targets for the adoption of electric vehicles and the production of ethanol-blended fuel to reduce vehicle emissions and improve air quality.

The consequences of vehicle emissions are severe, contributing to global warming and climate change. Exposure to particulate matter and other pollutants from vehicle emissions can cause serious illnesses such as lung cancer, stroke, and heart disease, leading to premature deaths and significant economic losses. Therefore, tackling vehicle emissions is crucial for improving air quality and protecting the health and well-being of India's population.

Construction dust and debris

Construction sites are significant sources of particulate matter pollution, with dust generated during various processes, including excavation, demolition, and material transportation. This dust contains harmful particles such as metalliferous dust, rock dust, finely powdered materials, coal dust, and crystalline silica dust. When these particles become airborne and reach high densities, they can cause severe health issues, especially for those with asthma or other respiratory ailments.

The health impacts of construction dust are evident in studies conducted in Delhi, India. The analysis revealed an estimated 7,350-16,200 premature deaths and 6 million asthma attacks annually due to particulate pollution. Additionally, a Central Pollution Control Board study found that 23% of children in urban Delhi exhibited upper and lower respiratory symptoms. Another study by Jamia Millia Islamia's Civil Engineering Department at 19 construction sites in Delhi found excessive levels of PM10, a harmful particulate matter.

Several factors contribute to the prevalence of construction dust pollution. The absence of green curtains around construction sites, inadequate sprinkling of water on debris, and discontinuation of practices like road sprinkling have been identified as aggravating factors. Furthermore, traditional construction methods that involve on-site material breaking and crushing, along with outdated equipment, exacerbate the problem.

To mitigate the impact of construction dust on air quality, effective measures must be implemented. This includes adopting dust control measures at construction sites, ensuring regular sprinkling of water to suppress dust emissions, and enforcing guidelines for construction projects. India has recognised the urgency of addressing air pollution and has implemented initiatives such as the National Clean Air Programme, aiming to reduce particulate matter concentrations.

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