Air pollution in Delhi
The air pollution in Delhi, the capital of India, was found to be the most harmful of any major city in the world in an August 2022 survey of 7,000 world cities by the US-based Health Effects Institute. The air pollution in Delhi also affects the surrounding districts. Air pollution in India is estimated to kill about 2 million people every year and is the fifth largest cause of death in India. India has the world's highest death rate from chronic respiratory diseases and asthma, according to the World Health Organization. In Delhi, poor air quality has irreversibly damaged the lungs of 2.2 million children.
On 25 November 2019, the Supreme Court of India expressed their sentiments on the pollution in Delhi, saying "Delhi has become worse than narak (hell)". Supreme Court Justice Arun Mishra remarked that it is "better to get explosives, (and) kill everyone."
During the COVID-19 pandemic lockdown in India, the air quality in Delhi significantly improved.
India's Ministry of Earth Sciences published a research paper in October 2018 attributing almost 41% of air pollution to vehicular emissions, 21.5% to dust and 18% to industrial emissions. The director of the Centre for Science and Environment alleged that the Society of Indian Automobile Manufacturers was lobbying "against the report" because it was "inconvenient" to the automobile industry.
The air quality index (AQI) in Delhi generally falls within the Satisfactory (51–100) and Moderate (101–200) ranges between March and September, and then drastically deteriorates to Poor (201–300), Severe (301–400), or Hazardous (401–500+) levels between October and February due to various factors including 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.
In November 2016, in an event known as the "Great Smog of Delhi", the air pollution spiked far beyond acceptable levels. The levels of PM2.5 and PM 10 particulate matter hit 999 micrograms per cubic meter, well above their respective 24-hour peak limits of 15 and 60 micrograms per cubic metre.
According to Bloomberg, 16.7 lakh (1,670,000) people died due to polluted air in India in 2019. According to data released by the Ministry of Environment, Forest and Climate Change in 2022, the Air Quality Index in Delhi stood at over 200 for at least half the year.
Animal agriculture also contributes to Delhi's pollution problem, as smog and other harmful particles have been produced by farmers burning their crops in other states since the 1980s.
An initiative that is being considered to address air pollution is a 1,600 km long and 5 km wide green ecological corridor along the Aravalli Range from Gujarat to Delhi connecting to the Sivalik Hills range. This would involve the planting of 1.35 billion (135 crore) new native trees over 10 years to combat pollution. In December 2019, IIT Bombay, in partnership with the McKelvey School of Engineering of Washington University in St. Louis, launched the Aerosol and Air Quality Research Facility to study air pollution in India.
The Delhi government announced in November 2021 that it would be shutting all schools and government offices for a week due to the severe air pollution. The government told the Supreme Court that it was confident and prepared for a complete lockdown. The Supreme Court asked authorities in the NCR region to consider remote work policies for employees. When the air quality in Delhi on 18 November 2021 slipped into the "severe" category with an AQI of 362, the Supreme Court of India reprimanded the central and state governments and asked them to take strict measures to reduce pollution in Delhi and the NCR region.
In November 2023, New Delhi was suffering from particularly high levels of air pollution. 38% of this year's pollution has been caused by stubble burning a practice where stubble left after harvesting rice is burnt to clear fields.
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, as reported by India's pollution control authority, indicates hazardous conditions with significant health impacts, particularly for vulnerable populations. The reading marks the highest AQI level for Delhi in 2024.