Delhi's Air: Polluted Or Not?

Delhi, India's capital, is one of the world's most polluted cities. The city's air quality is frequently classified as 'very poor', 'severe', or even 'hazardous', with the annual average PM2.5 concentration rising from 102.4 micrograms per cubic meter in 2023 to 108.3 micrograms per cubic meter in 2024. This is significantly higher than the World Health Organization's (WHO) recommended limit of 5 micrograms per cubic meter. Delhi's pollution stems from various factors, including vehicular emissions, industrial activities, agricultural residue burning, and natural factors, posing significant health risks to its residents.

Delhi's air quality is categorised as 'severe'

Delhi's air quality is categorised as severe, with the city ranking as the world's most polluted capital for the fourth consecutive year in 2023. The air pollution in Delhi is so severe that it affects the surrounding districts and is considered a silent killer, taking lives and impacting the health of millions of residents.

In November 2023, New Delhi recorded extremely high levels of air pollution, with the Air Quality Index (AQI) reaching over 400, indicating hazardous conditions. The city's air pollution stems from various sources, including vehicular emissions, industrial outputs, agricultural residue burning, and adverse weather patterns. Vehicles account for about 38% of the city's air pollution, with car ownership doubling since 2005 and congested roads. Rapid industrialisation has also led to increased pollution from factories, power plants, and construction sites, emitting pollutants such as sulfur dioxide and nitrogen oxides.

Agricultural practices in neighbouring states, such as stubble burning, significantly impact Delhi's air quality, especially during the winter crop-burning season. This practice can account for up to 45% of Delhi's pollution during this period. Additionally, Delhi's geographical location makes it susceptible to natural air pollutants, such as dust storms from the Thar Desert.

The poor air quality in Delhi has severe health implications. It is estimated that the air pollution in Delhi shortens the lifespan of its residents by 11.9 years. The high levels of pollution have irreversibly damaged the lungs of 2.2 million children in the city. Exposure to PM2.5 air pollution exacerbates health conditions such as asthma, cancer, stroke, and lung disease. It can also impair cognitive development in children and lead to mental health issues.

To address the air pollution crisis, various initiatives are being considered, such as the Graded Response Action Plan (GRAP) and the installation of air purification systems like smog towers. Additionally, a proposed 1,600 km long green ecological corridor along the Aravalli Range, involving the planting of 1.35 billion new native trees over 10 years, could help combat pollution in the region.

Delhi is the world's most polluted capital city

Delhi, the capital of India, is the world's most polluted capital city. In March 2024, Delhi was ranked as the world's most polluted capital city for the fourth consecutive year. The air quality in Delhi is so poor that it has been compared to a "gas chamber" and declared "worse than hell".

The air pollution in Delhi is caused by a combination of factors, including vehicular pollution, industrial outputs, agricultural residue burning, and adverse weather patterns. Vehicles account for 38% of the city's air pollution, with car ownership having doubled since 2005. The city's roads are struggling to keep up, and Delhi is ranked as the 44th most congested city in the world. In addition to vehicular pollution, industrial pollution from factories, power plants, and construction sites also contributes significantly to the poor air quality in Delhi.

Agricultural practices in the neighbouring states of Punjab, Haryana, and other states also impact Delhi's air quality. Farmers often burn the leftover straw and stubble in their fields to clear the land for the next crop cycle, releasing large amounts of particulate matter and carbon monoxide into the atmosphere, which winds carry into Delhi. This practice can account for up to 45% of Delhi's pollution during the crop-burning season.

The poor air quality in Delhi has severe health impacts on its residents. It is estimated that poor air quality reduces the lifespan of people living in Delhi by 11.9 years. In Delhi, poor air quality has irreversibly damaged the lungs of 2.2 million children. Exposure to elevated levels of fine particles can impair cognitive development in children, lead to mental health issues, and exacerbate existing illnesses such as asthma, cancer, stroke, lung disease, and diabetes.

While the government has implemented initiatives such as the Graded Response Action Plan (GRAP) to address air pollution, these measures have been criticized for targeting the symptoms rather than the root causes. Delhi's air pollution continues to be a significant concern, impacting the health and well-being of its residents.

The air pollution in Delhi is a public health crisis

Delhi's air pollution is driven by a range of factors, including vehicular emissions, industrial pollution, agricultural practices, and natural factors. With car ownership doubling since 2005, vehicles account for 38% of the city's air pollution. The city's roads are struggling to keep up, and Delhi is ranked as the 44th most congested city globally. Additionally, rapid industrialization has led to increased emissions from factories, power plants, and construction sites, further contributing to the poor air quality.

The agricultural practices in the neighboring states of Punjab and Haryana also significantly impact Delhi's air quality, particularly during the winter months. Farmers in these states often burn leftover straw and stubble in their fields, releasing large amounts of particulate matter and carbon monoxide into the atmosphere, which winds then carry into Delhi. The city's geographic location also makes it susceptible to natural air pollutants, such as dust storms from the Thar Desert.

The government has launched multiple initiatives to tackle Delhi's air pollution crisis, including the Graded Response Action Plan (GRAP) and the use of drones to spray mist in high-pollution areas. However, these efforts face challenges due to cost concerns, limited effectiveness, and logistical obstacles. The public health impact of air pollution in Delhi continues to grow, with studies estimating that poor air quality reduces the lifespan of Delhi residents by 11.9 years.

The worsening air quality in Delhi is not just a local issue but also reflects the broader challenges of air quality management in India. With 13 of the world's top 20 most polluted cities located in the country, India continues to struggle with air pollution, ranking fifth globally in terms of smog levels. The crisis in Delhi highlights the urgent need for collective action to address the twin crises of air pollution and climate change, prioritizing the well-being of people over corporate profits.

Vehicular pollution is a major contributor to Delhi's poor air quality

Delhi's air quality is categorised as "severe", exceeding WHO limits by over 17 times and causing harmful effects on the health of its residents. It is the most polluted capital city globally, with 42 of the world's polluted cities located in India. Delhi's air pollution stems from various factors, including vehicular pollution, industrial emissions, agricultural practices, and natural factors.

Vehicular pollution is a significant contributor to Delhi's poor air quality, accounting for about 38% of the city's air pollution. The resumption of work and increased commuter traffic after the Diwali weekend further exacerbated the issue. The number of vehicles on the road has doubled since 2005, and Delhi is ranked as the 44th most congested city globally. This spike in vehicular emissions, combined with unfavourable meteorological conditions, paddy-straw burning, firecrackers, and other local pollution sources, results in hazardous air quality levels in Delhi during winters.

Vehicles emit secondary inorganic aerosols, such as sulfate and nitrate particles, which are formed by the interaction of gases and particulate pollutants from sources like power plants, refineries, and vehicles themselves. These aerosols are the second major contributor to Delhi's poor air quality, accounting for 30 to 35% of the city's air pollution. Calm winds and low temperatures allow the accumulation of these pollutants, and the situation is expected to persist for several days.

To address the issue of vehicular pollution, the Delhi government has considered implementing the odd-even car rationing scheme, which permits cars to operate on alternate days based on their registration numbers. Additionally, stringent measures have been put in place under the Graded Response Action Plan (GRAP), including a ban on construction work and the entry of polluting trucks into the city. These measures aim to mitigate the root causes of air pollution and protect the health and well-being of Delhi's residents.

Stubble burning in neighbouring states impacts Delhi's air quality

Delhi's air quality is a recurring concern, with the city frequently recording air quality index (AQI) values in the "severe" category, especially during winter. The air pollution in Delhi is influenced by various factors, including vehicular emissions, industrial activities, and natural factors. However, one significant contributor to Delhi's air pollution is the practice of stubble burning in neighbouring states, particularly Punjab, Haryana, and Uttar Pradesh.

Stubble burning is a common agricultural practice in these states, where farmers burn the leftover straw and stubble in their fields to clear the land for the next crop cycle. This practice releases large amounts of particulate matter, including PM2.5, and carbon monoxide into the atmosphere. The wind then carries these pollutants towards Delhi, impacting its air quality. Studies have shown that stubble burning in Punjab and Haryana has significantly contributed to the pollution load in Delhi, with a maximum daily mean contribution of around 30-35% during specific periods in 2021.

While stubble burning has long been blamed for the seasonal spike in pollution in Delhi, the reality is more complex. Local sources, especially vehicular emissions, also play a significant role. In recent years, there has been a decline in the contribution of stubble burning to Delhi's air pollution. For example, between October 12 and October 21, stubble burning accounted for only 0.92% of the PM2.5 levels in Delhi. However, the overall air quality in Delhi continues to worsen, with the annual average PM2.5 concentration rising from 102.4 micrograms per cubic metre in 2023 to 108.3 micrograms per cubic metre in 2024, far exceeding national and World Health Organization (WHO) standards.

To effectively address Delhi's air pollution crisis, a multi-pronged approach is necessary, targeting both regional and local contributors. This includes implementing measures to reduce vehicular emissions, such as accelerating the shift towards electric vehicles, improving public transportation, and promoting carpooling. Additionally, stricter controls on industrial emissions, construction dust, and waste management practices are crucial. Regional cooperation with neighbouring states is also essential to mitigate the impact of cross-border pollution on Delhi's air quality.

Delhi's air pollution has severe health implications, with studies estimating that poor air quality reduces the lifespan of residents by 11.9 years. It is important to continue monitoring and addressing this issue through a combination of technological solutions, policy interventions, and regional collaboration to improve the air quality and protect the health of those living in and around the city.

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