Kiera Jefferson
New Delhi, the capital of India, is the most polluted city in the world. The city's air quality index (AQI) routinely eclipses 700 during the winter months, posing severe health risks to its residents. Vehicular emissions, industrial activity, construction, road dust, and crop burning in nearby states all contribute to New Delhi's hazardous pollution levels. The elderly, pregnant women, young children, and those with pre-existing health conditions are among the most vulnerable demographics. While the AQI levels in New Delhi have shown some improvement in 2025 compared to previous years, the city continues to grapple with severe air pollution, with even moderate AQI levels considered dangerous to human health.
| Characteristics | Values |
|---|---|
| Air Quality Index (AQI) | 78 (Moderate) |
| PM2.5 | 24µg/m³ |
| PM10 | 79µg/m³ |
| Temperature | 28°C |
| Vehicular Emissions | Carbon monoxide (CO), nitrogen oxides (NOx), particulate matter (PM) |
| Industrial Emissions | SO2, NOx |
| Other Sources | Construction, road dust, crop burning, fires (wood, cow dung, landfill), smog |
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What You'll Learn
Vehicular emissions, including motorbikes, tuk-tuks, cars, trucks, and buses
New Delhi's air quality is currently rated as "Moderate". However, the city has witnessed dangerous levels of pollution in the past, with a reading of 339.5 μg/m³ of PM2.5 in early 2021, placing it in the "hazardous" category. Vehicular emissions from motorbikes, tuk-tuks, cars, trucks, and buses significantly contribute to this pollution.
Vehicular emissions are a major concern in New Delhi, with vehicles contributing about 64% of the city's pollution. This includes emissions from motorbikes, tuk-tuks, cars, trucks, and buses, which release harmful pollutants into the air. The main air pollutants emitted by these vehicles include carbon monoxide (CO), oxides of nitrogen (NOx), and particulate matter (PM).
Motor vehicles, particularly those running on petrol, are a significant source of CO emissions. The emission of CO from two-wheelers is about 61%, while personal cars contribute about 34%. NOx emissions, on the other hand, are predominantly associated with diesel-powered vehicles, with personal cars contributing up to 50% of these pollutants. Heavy commercial vehicles (HCVs) are also major contributors to particulate matter (PM) pollution, accounting for approximately 92% of PM emissions.
The impact of vehicular emissions on air quality in New Delhi is not evenly distributed throughout the day. Emissions of CO and NOx tend to peak during morning and evening office hours, coinciding with congestion on the roads. This results in an increased concentration of pollutants like nitrogen dioxide (NO2), which has been recorded at hazardous levels during peak traffic hours. The contribution of local on-road transport to PM2.5 levels is also highest during the evening traffic peak, with two- and three-wheelers being the primary sources.
The use of lower-quality fuels, such as diesel containing high amounts of sulfur, further exacerbates the problem. Older vehicles and poorly maintained engines also leak heavy amounts of oil vapors and emit higher levels of pollutants compared to newer, cleaner models. Additionally, the rapid increase in the number of vehicles in New Delhi has outpaced the expansion of road infrastructure, leading to more congested roads and higher pollution levels.
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Industrial sources, including factories and power plants
New Delhi's air quality index (AQI) is currently classified as "moderate". However, the city's air pollution levels have been extremely poor in recent years, with the air quality index exceeding 400 on several occasions, far surpassing the hazardous threshold of 300.
Power plants are major sources of ambient air pollution in New Delhi. According to a study, industrial sources account for 52% of NOx emissions, with power plants being the primary contributors. Additionally, 90% of SO2 emissions and 18% of overall air pollution in Delhi are attributed to industrial sources. The high levels of NOx and SO2 emissions from power plants and other industrial activities can have severe health impacts on the residents of New Delhi.
Factories and industrial zones also release large quantities of smog and haze, along with industrial effluence that can contain toxic chemicals and metals. These emissions can have both short-term and long-term health consequences for individuals exposed to them. Short-term effects include respiratory issues such as shortness of breath, severe coughs, and irritation to the eyes, nose, and throat. More severe long-term health issues may include chronic obstructive pulmonary disease (COPD), cancer, and damage to vital organs such as the liver, kidneys, and lungs.
It is important to note that industrial workers and their families, who often live near industrial areas, are at an increased risk of exposure to industrial pollution. The health impacts of air pollution from industrial sources can be devastating, affecting both the workers and the general population of New Delhi. Therefore, it is crucial to implement measures to reduce industrial emissions and improve the overall air quality in the city.
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Construction and road dust
Road dust is particularly problematic when combined with urban topography and specific weather conditions. For example, during periods of cold temperatures, lack of wind, and high humidity, dust and pollution can accumulate in the road channels of the city. If there is insufficient wind to blow away the accumulated dust and pollution, or rainfall to wash it away, the air quality can suffer massively.
Construction dust alone can account for nearly 30% of particulate pollution in Delhi. To tackle this, the Delhi government has proposed strict dust control measures at construction sites, including remote monitoring of larger construction projects on plot areas greater than 500 sqm. The government has also mandated the deployment of anti-smog guns in proportion to the area of construction.
Other measures to reduce construction and road dust include expanding the metro network, promoting electric vehicles, and cleaning inner roads and trees with mechanized sweepers. The Delhi government is also working to strengthen pollution monitoring through the installation of Automatic Number Plate Recognition (ANPR) systems at the city's border entry points to block polluting vehicles.
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Crop burning in nearby states
New Delhi, India's capital, is often regarded as the world's most polluted capital. The air pollution in the city is a result of various factors, including vehicular emissions, industrial activities, construction, and agricultural waste burning. While crop burning in the neighbouring states of Punjab, Haryana, Rajasthan, and Uttar Pradesh has been identified as a significant contributor to Delhi's air pollution, it is essential to understand the context and challenges faced by farmers in these states.
The practice of crop burning in these states is deeply rooted in the agricultural practices of the region. Farmers in Punjab and Haryana have traditionally grown rice in the summer and wheat in the winter, encouraged by government subsidies and minimum price guarantees for these crops. This crop rotation allows them to maximize their yield and income. However, after harvesting rice, they have a very short window to prepare their lands for winter sowing. The quickest and most cost-effective way to clear the fields and prepare them for the next crop is to set fire to the fields, burning the leftover stubble. While this practice has severe environmental consequences, contributing to the hazardous air quality in New Delhi and other nearby cities, farmers argue that they lack affordable and accessible alternatives.
The smoke from the burning fields, combined with emissions from coal-fired power plants and industrial activities, creates a deadly haze that hangs over Delhi and its neighbouring regions during the months of October through December. This period of crop burning coincides with colder weather, which traps the toxic smog over the region, exacerbating the pollution crisis. While the Indian government and environmental organizations have attempted to address this issue by banning crop burning and providing support to extinguish agricultural fires, the efforts have had limited success.
Farmers in these states often defend their practice, arguing that they are being scapegoated for a much wider problem. They highlight the lack of support from the government in adopting more expensive and advanced machinery and techniques for clearing their fields. The combine machines used for harvesting rice leave several inches of stubble in the ground, which was previously used for various purposes but is now considered waste. Without access to affordable alternatives, farmers continue to resort to burning, despite the negative impact on the environment and their health.
To effectively address the issue of crop burning in these states and reduce its impact on New Delhi's pollution levels, a multi-faceted approach is necessary. It involves providing farmers with financial and technological support to transition to alternative methods of crop residue management, such as machinery that can clear fields without burning. Additionally, improving soil health and promoting sustainable agricultural practices can help reduce the need for frequent burning. By working collaboratively with farmers and providing them with viable options, it may be possible to mitigate the pollution caused by crop burning in these states and improve the air quality in New Delhi and the surrounding regions.
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Wood, cow dung, and landfill fires
New Delhi's air quality is considered to be "bad", with high levels of pollution. In early 2021, PM2.5 levels reached 339.5 μg/m³, which is considered hazardous and detrimental to health. Vehicular emissions, industrial activity, and the open burning of waste all contribute to New Delhi's poor air quality.
One source of pollution is the burning of wood for cooking and other domestic purposes. While wood stoves are a significant contributor to pollution, they are still more commonly used than dung stoves.
Cow dung, or dry dung fuel, is a traditional source of fuel in India, used for cooking food in a hearth called a Chulha. In rural India, dried cow dung is a primary source of household cooking fuel, releasing particulate matter and air pollution. According to researchers at the Indian Institute of Science Education and Research (IISER) Mohali, cow dung-fired stoves are highly polluting. In 2020, dung stoves emitted an estimated 1,600 gigagrams of PM2.5, which was about 17% more than wood stoves.
To address the issue of dung stoves, the Indian government launched the Pradhan Mantri Ujjwala Yojana in 2016, a program to encourage the use of liquefied petroleum gas and provide subsidies to reduce pollution and improve productivity. Researchers have also suggested that infrastructure to reduce agricultural air pollution could be utilised to reduce emissions from cow dung. For example, in Punjab, the government has set up biogas facilities to convert crop residue into cleaner-burning methane, which farmers can use in exchange for depositing agricultural waste.
In addition to wood and cow dung fires, landfill fires also contribute to New Delhi's air pollution. The Ghazipur landfill, one of around 3,000 Indian landfills, has been the site of multiple fires, releasing hazardous fumes and methane emissions. In April 2024, a fire at the landfill caused dangerous heat and methane emissions, with nearby residents complaining of throat and eye irritation. The trash mountain at Ghazipur stands at 65 meters (213 feet) tall, and the landfill has surpassed its capacity, with over 2,300 metric tons of solid waste arriving daily.
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Frequently asked questions
As of August 2025, the air quality in New Delhi is moderate, with an Air Quality Index (AQI) of 78. The PM2.5 level is 24µg/m³ and the PM10 level is 79µg/m³.
Vehicular emissions are a significant contributor to New Delhi's air pollution. Fumes from motorbikes, tuk-tuks, cars, trucks, and buses, as well as lower-quality fuels containing higher amounts of sulfur, all contribute to the poor air quality. Other sources include industrial emissions from factories and power plants, construction, road dust, crop burning, and the burning of wood, cow dung, and landfill.
New Delhi's annual AQI in 2025 is 145, which shows an average improvement of -11.6% compared to the previous four years: 2020 (153), 2021 (162), 2022 (174), and 2024 (169). However, it's important to note that during the winter months from October to February, AQI levels routinely eclipse 700, posing severe health risks.
While anyone can be affected by hazardous levels of PM2.5, certain demographics are more vulnerable. This includes young children, the elderly, pregnant mothers, individuals with pre-existing health conditions or compromised immune systems, and those with a predisposition to chemical sensitivity.
