Delhi's Air Pollution: Environmental Impact And Concerns

Delhi, the capital territory of India, is known for being one of the most polluted cities globally, with air pollution levels reaching hazardous levels that severely impact the health and environment of its residents. The poor air quality in Delhi is attributed to various sources, including vehicular emissions, industrial activities, crop stubble burning, firecrackers, and garbage waste. These pollutants contribute to respiratory problems, cardiovascular issues, and adverse effects on the natural environment, leading to concerns about the overall quality of life in the city. The Indian government has implemented measures to combat air pollution, but the situation remains critical, especially during the winter months.

Impact on human health

Delhi's air pollution has a significant impact on human health, causing a range of respiratory and other health issues. The high levels of air pollution in the city are linked to an increased prevalence of respiratory symptoms such as dry cough, wheezing, breathlessness, and chest discomfort. The city's air pollution has also been associated with a higher incidence of upper and lower respiratory tract infections, asthma, and reduced lung function. In addition, Delhi's air pollution has been linked to an increased risk of cancer, premature death, hypertension, chronic headache, eye irritation, and skin irritation.

The impact of air pollution on human health is particularly severe for vulnerable populations, including the elderly, children, and people with chronic lung diseases, influenza, or asthma. These individuals are especially sensitive to the effects of particulate matter, which can reach the lower regions of the respiratory tract and lead to adverse health outcomes. The health effects of air pollution are not limited to the respiratory system, as studies have also found correlations between air pollution and attention-deficit hyperactivity disorder, increased blood lead levels, and decreased vitamin D levels.

The poor air quality in Delhi has been found to contribute to infections and diseases that kill around 600,000 children under five years of age every year. Additionally, air pollution is associated with a higher prevalence of symptoms of chronic bronchitis and is estimated to cause approximately 2.5 million deaths worldwide each year. The impact of air pollution on health is not limited to the residents of Delhi, as the pollution affects a much larger area, including the neighbouring states of Haryana, Uttar Pradesh, and even Alwar in Rajasthan.

The air pollution in Delhi has severe consequences for the health of its citizens, and the situation is worsening. Several factors contribute to the poor air quality, including vehicular emissions, industrial activities, crop stubble burning, firecrackers, and waste burning. The government has implemented various measures to combat air pollution, such as the Graded Response Action Plan and the Odd-Even rule for vehicles, but more needs to be done to effectively reduce air pollution levels and mitigate its impact on human health. Individual actions, such as the use of air purifiers, masks, and reducing carbon footprints, are also crucial in protecting personal health.

Impact on the environment

Delhi's air pollution has a significant impact on the environment, causing harm to the natural world and contributing to global warming. The Indian capital, with a population of over 30 million, is known for being one of the world's most polluted cities, and the situation is worsening.

Greenhouse Gases and Global Warming

Delhi's air pollution is a major contributor to global warming due to the high levels of greenhouse gas emissions. Burning fossil fuels, such as the coal used in thermal power plants, releases carbon dioxide, which has the most significant impact on global warming. According to a study, crop residue burning in neighbouring states also releases substantial amounts of carbon dioxide and other greenhouse gases, including carbon monoxide, oxides of sulphur, and black carbon.

Harm to Natural Environment

The poor air quality in Delhi affects not just human health but also the natural environment. The high levels of pollutants in the air, such as particulate matter, lead, and other harmful gases, have consequences for the local ecosystem. Delhi's air pollution has led to reduced visibility, causing accidents and disruptions to transport services. The city's smog is so thick that it is visible from space, as seen in satellite images captured by NASA.

Impact on Surrounding Areas

Delhi's air pollution extends beyond the city limits, affecting the wider region. The severe air pollution affects a huge airshed around Delhi, including the National Capital Region (NCR) and neighbouring states such as Haryana, Uttar Pradesh, and even Rajasthan. The north-westerly winds from these states, and sometimes Pakistan and Afghanistan, bring dust into the region, and the Himalayas obstruct the escape route for the polluted air, causing it to settle in the Delhi area.

Vehicular emissions

The high number of vehicles in Delhi, estimated at 1.50 crores in 2021, has severe environmental implications. The emissions from these vehicles contribute to the city's deteriorating air quality, which has irreversible impacts on the health of its residents, particularly children. Vehicular emissions release pollutants such as secondary inorganic aerosols, which include particles like sulphate and nitrate. These pollutants form in the atmosphere due to the interaction of gases and particulate pollutants from power plants, refineries, and vehicles. Calm winds and low temperatures further hinder the dispersion of pollutants, allowing them to accumulate and worsen air quality.

The impact of vehicular emissions on Delhi's environment is evident in the city's Air Quality Index (AQI) readings. On November 18, 2024, Delhi recorded its worst air quality of the season, with a 24-hour AQI reading of 491, classified as "severe plus". This level indicates hazardous conditions with significant health impacts, particularly for vulnerable populations. The high AQI readings in Delhi are a result of the combination of vehicular emissions and unfavourable meteorological conditions, which make it difficult for pollutants to disperse.

To address the issue of vehicular emissions, the Delhi government has implemented various measures. These include the odd-even car rationing scheme, which allows cars to operate on alternate days based on their registration numbers, and the promotion of public transportation. Additionally, the government has banned the entry of commercial petrol and diesel vehicles into the city. Despite these efforts, Delhi continues to struggle with severe air pollution, and residents are advised to stay indoors and take precautions such as wearing masks when outdoors.

The high levels of vehicular emissions in Delhi have severe environmental consequences. The emissions contribute to the city's hazardous air pollution, which poses significant health risks to residents, especially children. The Delhi government has implemented measures to reduce vehicular emissions, but the city continues to face challenges in mitigating this issue.

Industrial activities

Delhi, the capital territory of India, has been deemed the most polluted major city in the world. Industrial activities are a significant contributor to this poor air quality.

Delhi is part of the Gurgaon-Delhi-Meerut Industrial Region, a highly significant economic region in India. Industrial areas cover 51.81 km2 of the National Capital Territory of Delhi's landscape. The city has consistently ranked among the most polluted metropolitan areas globally, with respiratory patients twelve times the national average and nearly 30% of the population suffering from respiratory diseases due to air pollution.

The increase in registered and operating industries in Delhi has led to a rise in air pollutant concentrations. Delhi's intricate urban environment concerning air pollution has seen annual mean levels of PM10 and NO2 exceed standard limits, with PM2.5 also surpassing the annual average in 2017. Chemical, textile, cement, steel, basic metal, mining, petroleum refineries, and thermal power plants are among the industries that have the potential to impact air quality.

A 2016 study on the sources of Delhi's air pollution revealed that 11% of PM2.5 pollution and 10% of PM10 pollution came from industrial point sources. Additionally, 52% of NOx emissions and 90% of SO2 emissions were attributed to industrial sources. The presence of various industries, including textiles, metal, paper products, rubber, plastic, and petroleum, further contributes to the city's air pollution.

Impact on Human Health

The health effects of air pollution in industrial areas have become a pressing issue in recent years. Exposure to air pollutants such as PM10, PM2.5, NO2, and CO can lead to respiratory diseases, chronic respiratory symptoms, aggravated asthma, decreased lung function, emergency room visits, hospital admissions, and premature mortality. Industrial workers and their families, who often live near industrial areas, are at high risk of these health problems. The productivity and survival of workers are affected, impacting the overall economic and social growth associated with industrialization.

Government Initiatives

To address the issue of industrial air pollution in Delhi, the government has formed 58 teams to monitor industrial units and ensure compliance with environmental regulations. As part of the city's Winter Action Plan, special focus is placed on reducing pollution during the winter months, with 191 patrol teams deployed to ensure the proper disposal of industrial waste. Non-compliance with environmental standards will result in strict punitive measures. Additionally, 1,901 industrial units have switched to Piped Natural Gas (PNG) to curb pollution from industrial operations.

Stubble burning

In 2021, a scientific study found that stubble burning in the states of Punjab and Haryana contributed to around 30-35% of the air pollution in Delhi during the post-monsoon season. The contribution peaked in the first week of November, with a daily mean of around 35-40%. However, it's important to note that the impact of stubble burning on Delhi's air quality varies throughout the year.

In 2024, stubble burning in Punjab and Haryana was responsible for a staggering 38% of Delhi's pollution on November 16, according to data from the Indian Institute of Tropical Meteorology (IITM) in Pune. This was the highest contribution recorded so far that year, surpassing the previous peak of 36% on November 1. For several consecutive days, stubble burning accounted for over 30% of Delhi's pollution.

While stubble burning is a major factor, other sources also contribute to Delhi's air pollution. Vehicular emissions, for example, remain the second-largest source, accounting for 11.7% of pollution. Industrial activities, residential practices, road dust, construction, and garbage burning also play a role, each contributing around 1-3% to the overall pollution levels.

The issue of stubble burning has become a political flashpoint, and the Indian government has implemented various measures to address it, including providing subsidies for farm equipment to manage crop residue without burning. However, the problem persists, and there is increasing pressure on the government to take more stringent action.

Frequently asked questions