Delhi's Air Pollution: Understanding The Key Causes

Delhi, India's capital, has the poorest air quality among capital cities globally. The city's air pollution is caused by a combination of natural and human-made pollutants. Vehicular emissions are a major contributor to Delhi's air pollution, with millions of cars on the roads. The lack of sufficient public transport options forces many people to depend on private cars, causing constant traffic jams and increasing air pollution. In addition, industrial emissions, construction activities, and agricultural practices contribute significantly by releasing dust particles and harmful chemicals, which increase particulate matter in the air. The burning of agricultural waste by farmers in neighbouring states, as well as the use of firecrackers during festivals, further adds to the air pollution in Delhi.

Vehicular emissions

Delhi, India's capital, has the poorest air quality among capital cities globally. The city's air pollution is caused by a combination of natural and human-made pollutants. Vehicular emissions are a major contributor to Delhi's poor air quality.

Motor vehicle emissions are one of the leading causes of Delhi's air pollution. The city's roads are crowded with vehicles, many of which are old and release high levels of harmful gases. The lack of sufficient public transportation options forces many people to rely on private cars, resulting in constant traffic jams and elevated air pollution levels. Vehicle emissions, particularly from heavy traffic, release carbon monoxide, nitrogen oxides, and hydrocarbons, which intensify pollution in congested areas.

According to a study by the Centre for Science and Environment, vehicular emissions are the largest contributor to Delhi's air pollution, accounting for 51.5% of the city's pollution during the period of October 12 to November 3, 2024. Another study by IQAir also identified vehicle emissions as a significant contributor to Delhi's declining air quality.

The large number of vehicles on Delhi's roads is due in part to the city's rapid urban growth, which has put immense pressure on its infrastructure. The increasing population means more cars, more waste, and higher energy consumption, all contributing to rising pollution levels. Additionally, court-ordered restrictions on bus services in Delhi have led to more people purchasing private cars, further exacerbating the problem.

To address the issue of vehicular emissions, the Delhi government has implemented several measures. They have added 1,000 extra CNG buses to the public transport fleet. The Supreme Court of India has also suggested that government officers living in government colonies should commute through carpooling or public transportation. Furthermore, diesel cars over ten years old and petrol cars over fifteen years old are banned in Delhi due to their higher pollution levels.

Overpopulation

Delhi, India's capital, is the most polluted capital city in the world. With a population of over 20 million, the city's rapid urban expansion puts a lot of strain on its infrastructure. Overpopulation contributes to the many types of pollution, including air pollution.

The overpopulation in Delhi has resulted in a significant increase in the number of vehicles on the road. Vehicular emissions are a major contributor to Delhi's air pollution, with emissions from millions of cars releasing harmful gases such as carbon monoxide, nitrogen oxides, and hydrocarbons. The lack of efficient public transportation options forces many people to rely on private cars, leading to frequent traffic jams and further increasing air pollution levels.

The large population also results in increased waste and energy consumption. The burning of garbage and the use of dirty fuels for cooking and heating contribute to the air pollution in Delhi. Additionally, the high energy demand leads to greater emissions from thermal power plants.

Furthermore, the high population density in Delhi contributes to noise pollution, which can also have indirect effects on air quality. Overall, the overpopulation in Delhi exacerbates the various types of pollution, including air pollution, and poses significant challenges to the city's infrastructure and environment.

Crop stubble burning

The burning of crop stubble releases atmospheric particulate matter (PM) and trace gases, which have severe health and environmental implications. These pollutants, along with dust particles, are carried by the wind and get locked in the air over Delhi, leading to smog formation and reduced air quality. The rapid increase in air pollution episodes in Delhi has been attributed, in part, to the seasonal burning of crop residues in these upwind regions.

Several factors contribute to the persistence of stubble burning. Firstly, there is a delay in the harvesting of Kharif crops due to the utilisation of monsoonal rains for cultivation instead of depleting groundwater. This postpones the burning of stubble by about 10-12 days, pushing it closer to the post-monsoon and winter seasons. Secondly, there has been an underestimation of crop residue burning emissions from Haryana and Uttar Pradesh due to challenges in detecting partially burnt areas. This has led to uncertainties in modelling the contribution of stubble burning to air quality in northern India.

To address the issue of stubble burning, the Indian government has implemented various measures. In 2022, the central government launched the Promotion of Agricultural Mechanisation for In-situ Management of Crop Residue scheme in Punjab, Haryana, Uttar Pradesh, and Delhi NCR. The scheme subsidised the cost of in-situ crop residue management (CRM) equipment, encouraging their adoption. Punjab received significant financial support under this initiative. Additionally, the Supreme Court has criticised the lack of enforcement of environment laws and the ineffective implementation of the Commission for Air Quality Management (CAQM) Act, which includes penalties for stubble burning.

Fireworks

The use of firecrackers during Diwali has been a controversial issue. While authorities banned traditional firecrackers in 2017 and allowed only environmentally friendly lights, the rule was not effectively enforced. The Supreme Court intervened in 2024, criticising the timing of the Delhi government's ban, which was imposed just before Diwali, speculating that stockpiling may have already occurred. The Court stressed that religious activities should not compromise the environment or public health.

The hazardous levels of air pollution in Delhi during the winter of 2024, with a 24-hour Air Quality Index (AQI) reading of 491, were classified as "severe plus." This reading indicated hazardous conditions with significant health impacts, particularly for vulnerable populations. The crisis is deepened from October to January, when colder temperatures coincide with widespread crop stubble burning in neighbouring states, and fireworks during Diwali.

The Supreme Court of India has taken an active role in addressing Delhi's air pollution crisis. In addition to reprimanding the government and addressing the issue of firecrackers, the Court has suggested that government officers living in government colonies commute through carpooling or public transportation. These suggestions aim to reduce the number of private cars on the roads, which contribute to the city's congested traffic and high pollution levels.

Delhi's toxic smog season typically occurs during the winter, and the capital region of 33 million people is consistently ranked among the most polluted areas globally. The combination of emissions from vehicles, fumes from construction, and the use of fireworks during festivals, all contribute to the severe air pollution levels in Delhi. The city's rapid urban growth and overpopulation further exacerbate the problem, leading to more cars, more waste, and increased energy consumption, all contributing to higher pollution levels.

Industrial emissions

Delhi, India's capital, has the poorest air quality among capital cities globally. The city's air pollution is caused by a combination of natural and human-made pollutants. Industrial emissions are a significant contributor to Delhi's poor air quality. These emissions include harmful pollutants such as sulfur dioxide, nitrogen oxides, and volatile organic compounds, which lead to the formation of secondary pollutants like ozone. Industrial activities, such as thermal power plants, contribute largely to these emissions.

In an attempt to tackle the issue, the Indian government has implemented several measures. For instance, the government has shut down 6 out of 11 thermal power plants in Delhi within a 300 km radius until the end of November 2021. This decision was made to reduce pollution and improve the air quality index. Additionally, the government has also banned the entry of trucks into Delhi and halted all construction activities for a period, aiming to decrease emissions from these sectors.

The private sector has also taken initiatives to address the problem. The India CEO Forum for Clean Air, including prominent businesses such as Wipro and Mahindra Group, is actively working towards improving air quality. These companies, along with the Clean Air Fund, are empowering healthcare professionals and amplifying health-focused voices in the clean air movement. Their efforts are crucial in ensuring clean and healthy air for everyone.

Despite these efforts, industrial emissions continue to be a significant concern. The Indian Institute of Technology Kanpur, in collaboration with the Department of Environment, Forest & Climate Change, is working to enable real-time monitoring of air quality. This will provide valuable data to inform effective strategies for reducing industrial emissions and improving Delhi's air quality.

Overall, industrial emissions are a critical factor in Delhi's air pollution crisis, and addressing them is essential for the health and well-being of the city's residents. By implementing regulations, encouraging sustainable practices, and promoting clean technologies, it is possible to mitigate the impact of industrial activities on the environment and public health.

Frequently asked questions