Delhi's Air Pollution: A Crisis And Its Causes

Delhi, the capital territory of India, has been recognised as the most polluted capital city in the world. The air pollution in Delhi is estimated to be responsible for 10,000 premature deaths per year, with the lungs of 2.2 million children irreversibly damaged by poor air quality. The primary sources of smoke are power plants, stubble burning, lit garbage, road dust, factories, and vehicles.

Delhi's air quality is the worst of any major city in the world

Delhi, the capital territory of India, has been recognised as the most polluted capital city in the world. A 2022 survey of 7,000 world cities by the US-based Health Effects Institute found that Delhi had the worst air pollution of any major city.

The air pollution in Delhi is estimated to cause 10,000 premature deaths per year and irreversibly damage the lungs of 2.2 million children. The World Health Organization (WHO) reports that India has the highest death rate from chronic respiratory diseases and asthma, with air pollution being the fifth-largest killer in the country, causing approximately 2 million deaths annually.

There are several factors contributing to Delhi's poor air quality. Motor vehicle emissions are a significant cause, with vehicles contributing 20% of PM2.5 and 36% of NOx emissions. In 2018, India's Ministry of Earth Sciences attributed almost 41% of air pollution to vehicular emissions. Other sources of pollution include industrial emissions, which account for about 18% of air pollution, with 90% of Delhi's SO2 emissions stemming from industrial sources. Fine particulate matter is the most dominant pollutant in Delhi, with the WHO reporting an annual average mass concentration of 121 µg/m3, 24 times higher than the recommended healthy level.

Agricultural practices also play a role in Delhi's air pollution. Stubble-burning in nearby states, such as Haryana and Punjab, can increase pollution levels in Delhi by over 45% during the winter months. The burning of crops during the harvest season, particularly in October, has been identified as the biggest cause of air pollution in Delhi. The Central Pollution Control Board (CPCB) reported a record-high hourly concentration of fine particulate matter of up to 1676 µg/m3 during the Diwali Festival, far exceeding the worst record in Beijing, China.

To combat air pollution, the Delhi government has implemented various measures. In 2016, the Chief Minister of Delhi proposed a series of steps, including banning construction and demolition work, diesel generator sets, and ash transportation from power plants. The government also introduced initiatives like vacuum cleaning and water sprinkling on roads. More recently, the Commission for Air Quality Management was established to enforce pollution control, and the Green Delhi app was launched to manage complaints and regulate dust. Additionally, the installation of smog towers and the use of the Pusa Bio-Decomposer to reduce stubble burning have been explored as solutions. Despite these efforts, Delhi's air quality continues to be a severe challenge, with AQI levels routinely eclipsing 700 during the winter months.

Fine particulate matter is the dominant pollutant, causing 10,000 premature deaths per year

Delhi, the capital territory of India, has been found to be the most polluted city in the world. In 2022, an analysis of 7,000 cities worldwide by the US-based Health Effects Institute revealed that Delhi had the worst air pollution of any major city. The air pollution in Delhi is estimated to cause around 2 million deaths per year, making it the fifth-largest killer in India.

Fine particulate matter, or PM2.5, is the dominant pollutant in Delhi's air. These tiny particles, measuring 2.5 micrometres or less in diameter, can be inhaled deep into the respiratory system, causing severe respiratory problems. According to the World Health Organization, safe levels of PM2.5 should not exceed 15 micrograms per cubic metre. However, in Delhi, these levels are frequently breached, with the air quality index often exceeding 400, far beyond the hazardous level of 500.

The sources of PM2.5 pollution in Delhi are varied. Motor vehicle emissions are a significant contributor, with vehicular emissions attributed to almost 41% of the city's air pollution. Other sources include wood-burning fires, cow dung combustion, agricultural fires, diesel generator exhaust, construction site dust, burning garbage, and illegal industrial activities. The burning of agricultural stubble in nearby Haryana and Punjab, combined with north-westerly winds, also significantly impacts Delhi's air quality.

The health consequences of inhaling fine particulate matter are dire. In addition to respiratory issues, exposure to PM2.5 has been linked to cardiovascular diseases and cancer. It can also trigger heart problems in those with pre-existing conditions, leading to heart attacks, irregular heartbeats, and increased blood pressure. The elderly and children are particularly vulnerable, with children facing a higher risk of developing respiratory issues and the elderly being more susceptible due to their weaker immune systems.

The high levels of PM2.5 in Delhi's atmosphere have resulted in an estimated 10,000 premature deaths per year. This figure represents the devastating impact of air pollution on the city's residents, with the irreversible damage to the lungs of 2.2 million children being one of the most alarming consequences.

Motor vehicle emissions are a major cause of poor air quality

Delhi has one of the highest vehicle densities in the world, with a large number of cars on the road contributing to high levels of air pollution. Motor vehicle emissions are a major cause of poor air quality in the city. The exhaust gases from vehicles contain a mix of toxic elements and chemicals, which have detrimental effects on both physical health and the environment.

Vehicular emissions are a significant contributor to particulate matter and ozone pollution, which have a negative impact on human health, climate, and vegetation. The high density of vehicles in Delhi leads to congestion, further increasing the concentration of vehicular emissions. The varied nature of the modelling domain, including residential, industrial, commercial, agricultural, and barn lands, also plays a role in the spatial and temporal disaggregation of emissions.

Various measures have been implemented to mitigate vehicular emissions in Delhi. The Bharat Stage Emission Standards (BSES) were introduced to reduce vehicular emissions, with several stages of norms proposed since 2000. The BS-VI norms, implemented in Delhi in 2017, aim to reduce emissions from vehicles. Additionally, compressed natural gas (CNG) fuel was introduced for public transport vehicles in 1998, and many private vehicles also adopted CNG. However, the difference in engine technologies between diesel and CNG-fuelled engines posed challenges in the transition.

Despite these efforts, the rising number of vehicles, along with factors such as road dust, construction, and industrial activities, continue to contribute to poor air quality in Delhi. The air pollution in Delhi has severe health implications, with irreversible lung damage reported in 2.2 million children. It is crucial for individuals, especially those utilizing private vehicles, to take responsibility and reduce their carbon footprint to improve air quality in the city.

To summarize, motor vehicle emissions are a critical factor contributing to Delhi's poor air quality. The high vehicle density, congestion, and toxic exhaust gases all play a significant role in this issue. While steps have been taken to mitigate vehicular emissions, the increasing number of vehicles on the road continues to pose a challenge. It is essential for both governmental and individual efforts to reduce emissions and improve air quality in Delhi.

The air pollution in Delhi affects the surrounding districts

Delhi, the capital territory of India, has been found to be the most polluted of any major city in the world. A 2022 survey of 7,000 cities by the US-based Health Effects Institute revealed that Delhi's air pollution was the worst. This air pollution is estimated to kill about 2 million people every year in India and is the country's fifth-largest killer. The World Health Organization has stated that India has the world's highest death rate from chronic respiratory diseases and asthma.

The air pollution in Delhi is caused by a variety of factors, including motor vehicle emissions, wood-burning fires, cow dung combustion, fires on agricultural land, exhaust from diesel generators, dust from construction sites, burning garbage, and illegal industrial activities. The air quality index (AQI) in Delhi generally falls within the moderate range between March and September, then deteriorates to poor, severe, or hazardous levels between October and February. The seasonal deterioration is due to factors such as the burning of effigies during Vijayadashami, the bursting of firecrackers during Diwali, thermal power plants in the National Capital Region, stubble burning, road dust, vehicle pollution, and cold weather.

The air pollution in Delhi has severe impacts on the surrounding districts. A recent analysis by Climate Trends revealed a strong correlation between stubble fire incidents in Punjab and Haryana and the deteriorating air quality in Delhi. The study, which examined data from 2019 to 2023, highlighted the urgent need for coordinated fire management and air quality interventions across state boundaries. The interconnectedness of environmental issues across states calls for urgent action from policymakers, agricultural experts, and environmental scientists to address the root causes of these fire incidents and protect public health in the region.

The Decision Support System (DSS), developed by the Indian Institute of Tropical Meteorology-Pune, can forecast the contribution of emissions from Delhi and the surrounding 19 districts of UP and Haryana to the city's air quality. The system can help identify the sources of particulate matter pollution and suggest possible solutions to policymakers. For example, on one day in October 2021, the DSS forecast that the contribution of Delhi's transport to the city's PM2.5 was likely to be around 25%, followed by biomass burning at 11%. The GRAP 3 restrictions, implemented in November 2024 due to severe air pollution, also impacted the surrounding districts of Gurugram, Faridabad, Ghaziabad, and Gautam Budh Nagar, with restrictions on vehicle use and construction.

The government has implemented action plans to combat air pollution

The Delhi government has introduced a 10-point action plan to combat air pollution in the winter season, which is when pollution is at its worst. This includes a complete ban on the sale and purchase of firecrackers, which resulted in the cleanest Diwali celebration in the last 7 years. The government has also formed 75 teams to inspect construction sites to control dust pollution and 250 teams to monitor waste burning. 500 teams have been constituted to check Pollution Under Control certificates, and steps will be taken to address traffic jams on 64 identified roads to reduce vehicle pollution.

The government has also launched a comprehensive 21-point Winter Action Plan, which includes real-time monitoring of pollution using drones, deploying special task forces, and implementing emergency measures such as artificial rain and vehicle rationing schemes. This plan also includes an anti-dust campaign from October 7.

To tackle pollution in the national capital, 233 teams are monitoring industrial sites, and 1600 industries are being inspected regularly. The government has also started spraying PUSA bio-decomposer in the farmlands of Delhi to combat pollution, covering nearly 3,200 acres so far.

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