Air pollution in Delhi, the capital of India, was found to be one of the most lethal of any city in the world in an August 2022 study of 7,000 world cities by the US-based Health Effects Institute. Air pollution in India is estimated to kill about 2 million people every year. 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, 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.Want govt to build 1600 km green wall along Aravalli, Indian Express, 24 December 2019. 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 2023's pollution has been caused by stubble burning.
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. The Bharatiya Janta Party-led Delhi Government was accused of deliberately distorting AQI data after Municipal Corporation of Delhi tankers (controlled by the BJP) were witnessed spraying water around air-quality monitoring stations in a bid to suppress actual readings that suggested catastrophic air quality.
Particulate matter levels in Delhi
Air quality or ambient/outdoor air pollution is represented by the annual mean concentration of particulate matter PM10 (particles smaller than 10 microns) and PM2.5 (particles smaller than 2.5 microns, about 25 to 100 times thinner than a human hair).
PM10 levels, for the period 2008 and 2013, based on data of 1600 cities in 91 countries, range from 26 to 208 micrograms per cubic meter of air (μg/m3), with the world average being 71 μg/m3. 13 of the 25 cities worldwide with the highest levels of PM are in India.
The 2022 version of the WHO ambient air quality database status report includes annual means for PM10, PM2.5, and NO2 for the years between 2010 and 2019, and it covers 6,743 human settlements in 117 countries worldwide. It documents the following annual mean concentration on particulate matter from 2010 to 2020 in Delhi: +YearPM2.5 (μg/m3)PM10 (μg/m3)NO2 (μg/m3)2010153274201123727020121192382013120226692014198216662015113214201614929269201712921320181062019105192202011419461 In 2010, the year of the WHO survey, the average PM10 level in Delhi was 286 μg/m3. In 2013, the PM2.5 level was 153 μg/m3. These levels are considered very unhealthy. In Gwalior, the city with the worst air quality in India, the PM10 and PM2.5 levels were 329 μg/m3 and 144 μg/m3 respectively. For comparison, the PM10 and PM2.5 levels in London were 22 μg/m3 and 16 μg/m3 respectively.
In December–January 2015, in Delhi, an average PM2.5 level of 226 μg/m3 was noted by US embassy monitors in Delhi. The average in Beijing for the same period was 95.Air Pollution in India: Real-time Air Quality Index Visual Map, http://aqicn.org/map/india/ Delhi's air is twice as bad as Beijing's air. As of November 2017, experts in several monitoring stations have reportedly measured an air quality index of 999. This is said to be the equivalent of smoking 45 to 50 cigarettes a day. This has led to chief minister of Delhi comparing the nation's capital to a "gas chamber".
According to the WHO ambient air quality database, 2022 status report update, recommended levels as of 2021 are 15 μg/m3 (annual mean) for PM10, 5 μg/m3 (annual mean) for PM2.5, and 25 μg/m3 (annual mean) for NO2. These guidelines have changed from those of 2005 which were 20 μg/m3 (annual mean) for PM10, 10 μg/m3 (annual mean) for PM2.5, and 40 μg/m3 (annual mean) for NO2.
Causes of poor air quality Motor vehicle emissions are one of the causes of poor air quality. Other causes include wood-burning fires, cow dung cake combustion, fires on agricultural land, exhaust from diesel generators, dust from construction sites, burning garbage and illegal industrial activities in Delhi. Although pollution is at its worst from November to February, Delhi's air misses clean-air standards by a wide margin for much of the year. On the worst days, the air quality index, a benchmark ranging from zero (good) to 500 (hazardous), exceeds 400. Thermal power plants in NCR. Agricultural stubble burning in Haryana and Punjab, coupled with north-westerly winds also affects Delhi's air quality since the 1980s when crops are being harvested. This is the biggest cause of air pollution in Delhi and as can be seen from air pollution index data, the air quality drastically deteriorated in October, the season of crop burning in Punjab and Haryana. During the crop-burning season, the practice can account for up to 45% of Delhi's pollution, according to government meteorologists. The drift/mist emissions from the wet cooling towers are also a source of particulate matter as they are widely used in industry and other sectors for dissipating heat in cooling systems. Although Delhi is kerosene free and 90% of the households use LPG for cooking, the remaining 10% uses wood, crop residue, cow dung, and coal for cooking. (Census-India, 2011) Fire in Bhalswa landfill is also a major reason for airborne particles in Delhi.
A study in 2016 measured the sources and average levels of various types of air pollution in Delhi. Of PM2.5 pollution, 38% came from road dust, 20% from vehicles, 12% from domestic fuel burning, and 11% from industrial point sources. Of PM10 pollution, 56% came from road dust, 10% from concrete batching, 10% from industrial point sources, and 9% from vehicles. Of NOx emissions, 52% came from industrial point sources (mostly from power plants and 36% from vehicles (but the 36% was potentially more damaging due to being emitted close to people). Of SO2 emissions, 90% came from industrial point sources. Of CO emissions, 83% came from vehicles.Comprehensive Study on Air Pollution and Green House, Mukesh Sharma and Onkar Dikshit (Indian Institute of Technology Kanpur), 2016 The large contributions of vehicles and road dust to air pollution have been made worse by court-ordered restrictions on bus service in Delhi, which had the effect of accelerating the purchase of private cars and the construction of roads to accommodate them.Altruism and Development - It's complicated.......
A collaborative study between IIT Delhi and IIT Kanpur concluded that biomass burning drive is the primary cause air pollution in Delhi following the days after Vijayadashami and Diwali. It also said that stubble burning and increased heating requirements of the region in winters increase the biomass burning activity.
Past causes
The Badarpur Thermal Power Station, a coal-fired power plant built in 1973, was another major source of air pollution in Delhi. Despite producing less than 8% of the city's electric power, it produced 80 to 90% of the particulate matter pollution from the electric power sector in Delhi. During the Great Smog of Delhi in November 2016, the Badarpur Power Plant was temporarily shut down to alleviate the acute air pollution but was allowed to restart on 1 February 2017. In view of the detrimental effect to the environment, the power plant has been permanently shut down since 15 October 2018.
Air quality index data of Delhi by month
MonthJanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecemberAverage air quality index301–400 (Severe)201–300 (Poor)101–200 (Moderate)101–200 (Moderate)101–200 (Moderate)101–200 (Moderate)51–100 (Satisfactory)51–100 (Satisfactory)51–100 (Satisfactory)201–300 (Poor)401–500 (Hazardous)401–500 (Hazardous)
Effects of poor air quality
Effects on children 22 lakh (2,200,000) children in Delhi have irreversible lung damage due to poor air quality. In addition, research shows that pollution can lower children's immune system and increase the risks of cancer, epilepsy, diabetes and even adult-onset diseases like multiple sclerosis. Children are more vulnerable to the negative effects of air pollution as they are growing and developing due to breathing a higher rate of air per kilogram of their body weight. They also spend more time outside and are thus more exposed to it.
Effects on adults Poor air quality is a cause of reduced lung capacity, headaches, sore throats, coughs, fatigue, lung cancer, and early death.
Control measures
In 2016, the Chief Minister of Delhi proposed these measures to reduce air pollution but didn't get any success due to the lack of implementation in reality. The efficacy of any individual step has been a matter of public debate.
All Delhi schools will remain shut for the next few days.