Timeline of pollution in Delhi

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This is a timeline of pollution in Delhi, a city that has frequently ranked among the most polluted in the world.[1]

Big picture

Time period Development summary
1980s Air and water pollution in Delhi emerge as significant public issues, prompting early intervention by the Supreme Court of India. Judicial involvement begins to shape environmental governance, marking the start of sustained legal oversight of pollution control.[2]
1990s Delhi reaches some of the worst urban air pollution levels in the world, driven by rapid urbanisation, industrial activity, and rising vehicular emissions. Severe health impacts and public concern lead to intensified civil society activism and major court-mandated interventions, including relocation of polluting industries.[3][4]
2000s Policy measures targeting vehicular emissions and fuel standards contribute to localized improvements, but rapid urban growth and expanding traffic offset gains. Air pollution spreads beyond central districts into residential areas, indicating a transition from localized to citywide environmental stress.[5]
2010s Despite extensive government policies, regulations, and judicial interventions, Delhi experiences recurring air pollution crises, particularly during winter months. Pollution levels reach extremes that affect even healthy individuals, reflecting the limited long-term effectiveness of existing measures and the persistence of structural drivers.[6]
2020s Delhi continues to rank among the most polluted cities globally, with seasonal smog crises, public health emergencies, and rising public frustration. New policy plans and emergency measures are introduced, but ongoing pollution highlights the enduring challenges of managing emissions from transport, industry, and regional sources such as crop burning.

Sample questions

The following are some interesting questions that can be answered by reading this timeline:

  • How did air pollution in Delhi evolve from a relatively minor issue into a chronic public health crisis?
    • Read the full timeline chronologically.
    • You will observe a transition from low pollution levels in the mid-20th century to severe and persistent pollution beginning in the 1990s.
  • What role has the Supreme Court of India played in addressing pollution in Delhi?
    • Sort the full timeline by "Type of event" and look for rows with value "Court ruling".
    • You will see repeated judicial interventions shaping environmental governance, particularly from the mid-1980s onward.
  • What are the main government policies introduced to control pollution in Delhi?
    • Sort the full timeline by "Type of event" and look for rows with value "Government policy".
    • You will identify measures targeting vehicular emissions, fuel standards, plastic use, and emergency traffic restrictions.
  • What regulatory frameworks have been established to manage environmental pollution?
    • Sort the full timeline by "Type of event" and look for rows with value "Regulation".
    • You will find laws and rules such as pollution control boards, waste management regulations, and emission standards.
  • What evidence exists regarding the health impacts of pollution in Delhi?
    • Sort the full timeline by "Type of event" and look for rows with value "Study".
    • You will see research quantifying mortality, air quality levels, and long-term exposure risks.
  • What are the major pollution crises recorded in Delhi?
    • Sort the full timeline by "Type of event" and look for rows with value "Crisis".
    • You will observe recurring emergency episodes, especially during winter months, with hazardous smog levels and public health alerts.
  • How effective have pollution control measures been over time?
    • Compare rows classified as "Government policy", "Regulation", and "Court ruling" with later rows classified as "Observation" or "Crisis".
    • You will find that despite numerous interventions, pollution levels remain persistently high, suggesting limited long-term effectiveness.
  • What are the main structural drivers of pollution in Delhi?
    • Read across rows describing studies and observations.
    • You will identify key contributors including vehicular emissions, industrial activity, urbanization, and regional crop burning.
  • How has public perception and social response to pollution evolved?
    • Focus on recent rows classified as "Crisis" and "Observation".
    • You will see increasing public concern, health warnings, and social pressure on authorities.
  • How does Delhi compare globally in terms of pollution levels?
    • Look for rows classified as "Study" and "Recognition".
    • You will find global rankings and comparative assessments placing Delhi among the most polluted cities in the world.

Full timeline

Year Pollution type Type of event Details
1947 Air pollution Baseline India becomes an independent state. At the time, fog in Delhi is rather rare.[7]
1950–1951 (December–February) Air pollution Observation Only one foggy day is reported in the winter months in the city.[7]
1955 Water pollution Crisis Sewage and industrial wastes from the Najafgarh drain cause a famous jaundice episode in Delhi. The Najafgarh drain comes to be known as "sorrow of Delhi"[8]
1974 Water pollution Regulation The Central Pollution Control Board is set up under the Water Act.[9]
1982 Air pollution, water pollution Urban planning Delhi passes its first Industrial Policy.[9]
1985 Air pollution Court ruling The Supreme Court of India issues a verdict to deal with the chronic problem of vehicular pollution in Delhi, one of the earliest stands taken by the judiciary.[9]
1987 Air pollution Study A survey estimates that 1172 tonnes of suspended particulate matter, hydrocarbons, sulphur dioxide, nitrogen oxides, carbon monoxide and other poisonous gases are emitted into the air in Delhi by industrial units, transport, and the power sector. The findings highlight the scale of pollution sources in the city, particularly the role of expanding industry and transport, and provide early quantitative evidence supporting the need for regulatory intervention.[10]
1990 – 2001 Air pollution, water pollution Urban planning A Master Plan of Delhi allows for "light" industry to be set up in residential areas. This creates a leeway for many industries... The policy facilitates the continued presence and expansion of small-scale industries within urban areas, contributing to sustained environmental pressures and complicating efforts to control pollution.[11]
1993 – 2000 Light pollution Study Author Pavan Kumar says New Delhi, along with Telangana, Maharashtra, Karnataka and Uttar Pradesh experienced increase in “very high light pollution intensity” in the period.[12]
1994 Water pollution Court ruling India’s Supreme Court takes suo motu notice of a newspaper report on pollution of the Yamuna River in Delhi. The intervention brings the Central Pollution Control Board and the Delhi government into the case, marking a turning point in judicial oversight of pollution control in the capital.[2]
1995 Air pollution Measurement Delhi’s air pollution reaches a critical peak, with suspended particulate matter rising to about 409 µg/m³. This reflects the rapid deterioration of air quality during the early 1990s, driven by accelerated urbanisation and a sharp increase in vehicular traffic, especially diesel-powered vehicles. The extreme particulate levels contribute to worsening winter fog and smog conditions and would later prompt judicial intervention, laying the groundwork for Supreme Court–mandated pollution control measures in the following years.[7]
1995 Air pollution, water pollution Court ruling The Supreme Court of India asks the Delhi Pollution Control Committee to categorize all industrial units in the city according to pollution hazard they pose.[13]
1995 Air pollution Government policy Delhi government introduces catalytic converter in passenger cars as vehicle control measure policy to curb air pollution in the city.[9]
1996 Air pollution Observation 46 foggy days are reported in the winter months in Delhi. The sharp increase compared to earlier decades reflects worsening air quality conditions and the growing impact of particulate pollution on visibility and public health.[7]
1996 (February) Water pollution Court ruling The Supreme Court of India orders the Delhi state government to construct common effluent treatment plants, which the industries are required to pay for, to reduce water pollution.[13]
1996 (April) Air pollution, water pollution Court ruling The Supreme Court of India orders the relocation of factories away from residential areas.[13]
1997 Air pollution Study The annual suspended particulate matter concentration in Delhi reaches 339.3 microgrammes per cubic meter. The high level confirms the persistence of severe air pollution following the early 1990s peak and underscores the limited effectiveness of initial control measures.[10]
1998 Air pollution Court ruling The Supreme Court of India orders a major transformation of Delhi's transportation system, in response to a public interest petition on air pollution.[13]
1998 Air pollution Government policy Delhi government introduces unleaded petrol as vehicle control measure policy to curb air pollution in the city.[9]
1998 Biomedical waste Regulation India enacts the Biomedical Waste Rules to regulate the storage, treatment, and disposal of biomedical waste in ways that protect public health and the environment. The rules apply to all biomedical waste generators, including hospitals, laboratories, and veterinary institutions. They establish approved treatment methods such as incineration and autoclaving, mandate color-coded waste segregation, prohibit storing untreated waste beyond 48 hours, and require disposal at authorized landfill or treatment sites.[11]
2000 Air pollution Government policy Delhi government introduces reduction of benzene content in fuels and reduction of sulfur content in diesel as vehicle control measure policy to curb air pollution in the city.[9]
2003 soil contamination, water pollution Regulatory enforcement After Supreme Court order on hazardous waste, stringent actions are prompted by various State Pollution Control Board in Delhi.[11]
2003 Air pollution Recognition Delhi wins the United States Department of Energy's first 'Clean Cities International Partner of the Year' award for its "bold efforts to curb air pollution and support alternative fuel initiatives".[14]
2007 Air pollution Study Studies find that converting buses from diesel to compressed natural gas in Delhi reduces particulates, carbon monoxide, and sulfur oxides, though some analyses identify more limited effects. The mixed results highlight both the benefits and limitations of fuel-switching policies in addressing urban air pollution.[3]
2009 Water pollution, soil contamination Government policy Delhi allows the use of only virgin plastic.[11]
2011 Electronic waste Regulation India’s Ministry of Environment and Forests enact the E-waste Rules, establishing a formal regulatory framework for electronic waste management. The rules assign clear responsibilities to producers, consumers, collection centers, dismantlers, and recyclers. Producers are required to collect and finance environmentally sound e-waste management under extended producer responsibility, while restricting hazardous substances in new equipment. Consumers must return e-waste only to authorized entities, and storage beyond six months is prohibited.[11]
2011 (September) Air pollution Study The World Health Organization releases urban air quality data showing that Delhi exceeds the maximum PM10 limit by nearly tenfold at 198 μg/m³. The findings reinforce global recognition of Delhi’s air pollution crisis and highlight the contribution of vehicle and industrial emissions to both outdoor and indoor air quality degradation.[9]
2012 Water pollution, soil contamination Government policy Delhi completely bans all plastic.[11]
2013 Air pollution Observation Delhi experiences a dramatic rise in foggy days, reaching 74 between December and February, compared with just one in 1951. This increase reflects long-term deterioration in air quality driven by rapid urbanisation and heavy vehicular traffic since the early 1990s, especially diesel vehicles. Although Supreme Court-mandated shifts to CNG in the late 1990s temporarily had reduced particulate matter levels, pollution remains severe by 2013, manifesting visibly through persistent winter fog and smog.[7]
2013 (January) Air pollution, water pollution, soil contamination Court ruling The Delhi High Court orders civic authorities to relocate a biomedical waste incinerator from a residential area to outside the city, citing CPCB guidelines that classify incinerators as hazardous to public health. The court references the Master Plan of Delhi 2021, which bans such industries in residential zones. This decision reinforces judicial enforcement of biomedical waste regulations.[11]
2013 (April) Air pollution Study A research paper by The Centre for Development Economics at Delhi School of Economics indicates that Delhi Metro helps reduce vehicular air pollution. The findings suggest that expansion of public transport infrastructure can play a significant role in mitigating emissions from private vehicles in rapidly growing urban areas.[15]
2014 (May) Air pollution Study The World Health Organization announces New Delhi as the most polluted city in the world based on urban air quality data. The designation draws global attention to the severity of Delhi’s pollution crisis and intensifies scrutiny of government policies aimed at improving air quality.[16]
2014 (December) Air pollution Study The Centre for Science and Environment classifies the air in Delhi as “severely polluted” for over 65 per cent of days. The finding underscores the chronic nature of the city’s air quality crisis and suggests that pollution is no longer confined to seasonal peaks.[17]
2015 (December) Air pollution Study A study estimates that Delhi loses about 80 lives to air pollution every day, amounting to roughly 10,000 to 30,000 deaths annually. The findings highlight the severe public health burden of air pollution and reinforce its status as a major environmental risk factor in the city.[17][18]
2015 (End of the year) Air pollution Government policy Severe air pollution in Delhi National Capital Region leads to a number of Supreme Court rulings, one banning the sale of diesel cars in the area with engine displacements greater than 2.0 L from January 1 to 1 April 2016.[19]
2016 (November) Air pollution Crisis Air pollution in Delhi reaches 16 times above safe levels, and the Delhi government declares an emergency.[6][20]
2017 (November) Air pollution Crisis A public health emergency is declared by the Indian Medical Association in Delhi as air quality index breached 999, likened to smoking 50 cigarettes a day. Air pollution raises to over 710 micrograms per cubic meter, more than 11 times the World Health Organisation’s safe limit.[21][22][23][24]
2017 (November 17) Air pollution Government policy The government of Delhi launches the odd-even rule in an attempt to reduce pollution in the nation's capital. It is based on the Odd-Even rationing method: This means that cars running with number plates ending in Odd digits could only be driven on certain days of the week, while the Even digit cars could be driven on the remaining days of the week.[25]
2017 (November 25) Air pollution Court ruling The Supreme Court of India bans the sale of firecrackers in Delhi to alleviate pollution.[26]
2017 (December) Air pollution Crisis During a test match between Sri Lankan and Indian cricket teams in New Delhi, Sri Lanka players begin to feel breathing problems and several players vomit both in the rest rooms and in the field and have to use face masks until the end of the match.[27]
2018 – 2019 (November 1 2018 – January 6 2019) Air pollution Observation According to a report, toxic levels of air pollution monitored over Delhi almost every week during the period shows that the government’s emergency plans to tackle the city’s annual crisis have failed.[6]
2019 (March) Air pollution Study A study published in Nature Sustainability finds that high pollution levels in New Delhi during fall and winter are largely driven by post-harvest crop burning, with emissions rivaling fossil fuel sources. The findings challenge the prevailing view that urban traffic is the dominant source and highlight the importance of regional agricultural practices in shaping city air quality.[28]
2024 (November) Air pollution Crisis Delhi orders the closure of all primary schools as hazardous smog worsens, shifting classes online indefinitely. Air pollution levels reach more than 50 times World Health Organization safety limits, with extremely high PM2.5 and PM10 concentrations affecting Delhi and nearby cities. The seasonal smog is driven by weather conditions, vehicle emissions, dust, and crop burning. Authorities impose mitigation measures, but critics say they remain ineffective.[29]
2025 (December) Air pollution Government policy Authorities in Delhi introduce a new policy plan aimed at reducing toxic air pollution through coordinated measures targeting transport, industry, and construction emissions. The plan emphasizes stricter enforcement and inter-agency coordination, but experts question whether implementation capacity and political will are sufficient to deliver sustained improvements in air quality.[30]
2026 (January) Air pollution Crisis Rising public anger over hazardous air pollution levels intensifies in Delhi, with residents expressing frustration over recurring winter smog and perceived government inaction. The growing dissatisfaction reflects the social and political costs of chronic air pollution and increases pressure on authorities to implement more effective long-term solutions.[31]
2026 (March 4) Air pollution Study A report by IQAir ranks Delhi among the top 10 most polluted cities in the world based on global air quality monitoring data. The ranking reinforces the city’s persistent position among the world’s most polluted urban areas despite decades of policy interventions and highlights the continuing severity of particulate pollution levels.[32]

Visual data

The comparative chart below shows Google Trends data for pollution in Delhi (Search term), Delhi air quality (Search term) and air pollution in India (Search term), from January 2004 to April 2021, when the screenshot was taken. Interest is also ranked by country and displayed on world map.[33]

Google Ngram Viewer

The comparative chart below shows Google Ngram Viewer data for Pollution in Delhi and pollution in Beijing, from 1945 to 2019.[34]

Wikipedia Views

The chart below shows pageviews of the English Wikipedia article Pollution in Delhi, from November 2017 to March 2021.[35]


Meta information on the timeline

How the timeline was built

The initial version of the timeline was written by User:Sebastian.

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See also

References

  1. ↑ "India takes steps to curb air pollution". who.int. Retrieved 10 May 2019.
  2. ↑ 2.0 2.1 Cite error: Invalid <ref> tag; no text was provided for refs named Environmentalism
  3. ↑ 3.0 3.1 Cite error: Invalid <ref> tag; no text was provided for refs named Delhi air quality
  4. ↑ "Delhi lacks long-term plan to check industrial pollution". hindustantimes.com. Retrieved 10 May 2019.
  5. ↑ Chauhan, Chetan. "Delhi cold brings pollution, illness". hindustantimes.com. Retrieved 10 May 2019.
  6. ↑ 6.0 6.1 6.2 "Despite government's emergency pollution plan, Delhi once again breathed deadly air through winter". scroll.in. Retrieved 8 May 2019.
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Balachandran, Manu; Thomas, Maria. "Delhi's air is so toxic that schools are closing, expats are fleeing, and the visiting UK PM could lose hours from her life". qz.com. Retrieved 12 June 2019.
  8. ↑ Agarwal, S. K. Water Pollution.
  9. ↑ 9.0 9.1 9.2 9.3 9.4 9.5 9.6 "Pollution in Delhi : A Chronic Problem". jagranjosh.com. Retrieved 9 May 2019.
  10. ↑ 10.0 10.1 Agarwal, S. K. Air Pollution.
  11. ↑ 11.0 11.1 11.2 11.3 11.4 11.5 11.6 Raju, K.V.; Ravindra, A.; Manasi, S.; Smitha, K.C.; Srinivas, Ravindra. Urban Environmental Governance in India: Browsing Bengaluru.
  12. ↑ "Not just air, light pollution too is on the rise in India". scroll.in. Retrieved 8 May 2019.
  13. ↑ 13.0 13.1 13.2 13.3 Bauer, Joanne R. Forging Environmentalism: Justice, Livelihood, and Contested Environments.
  14. ↑ "Express India". Cities.expressindia.com. Archived from the original on 31 December 2010. Retrieved 11 March 2011. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  15. ↑ "Delhi Metro helps reduce vehicular air pollution, indicates research". indiatoday.in. Retrieved 9 May 2019.
  16. ↑ Madhok, Madhok (16 October 2014). "Here is why India has no clue how bad its air pollution problem is". Quartz India. Retrieved 8 May 2019.
  17. ↑ 17.0 17.1 "Delhi loses 80 lives to air pollution every day, says study". downtoearth.org.in. Retrieved 8 May 2019.
  18. ↑ "Air pollution kills 30,000 in Delhi every year". hindustantimes.com. Retrieved 8 May 2019.
  19. ↑ Naseem, Mohammad; Naseem, Saman. Energy Law in India.
  20. ↑ "Indian government declares Delhi air pollution an emergency". theguardian.com. Retrieved 10 May 2019.
  21. ↑ "Toxic Air Is Now A Year-Round Problem For Delhi". bloombergquint.com. Retrieved 9 May 2019.
  22. ↑ "Delhi doctors declare pollution emergency as smog chokes city". theguardian.com. Retrieved 8 May 2019.
  23. ↑ "Delhi residents panic as 'deadly smog' returns". bbc.com. Retrieved 8 May 2019.
  24. ↑ "Delhi's air pollution is triggering a health crisis". bbc.com. Retrieved 8 May 2019.
  25. ↑ "Odd-Even Rule: 5 Things You Need to Know - NDTV CarAndBike". CarAndBike. Retrieved 24 May 2019.
  26. ↑ "Supreme Court bans sale of firecrackers in Delhi, NCR". Times of India. Retrieved 8 May 2019.
  27. ↑ Safi, Michael (2017-12-03). "Pollution stops play at Delhi Test match as bowlers struggle to breathe". The Guardian. ISSN 0261-3077. Retrieved 8 May 2019.
  28. ↑ "Burning Crops Are a Top Source of Air Pollution in India, Study Finds". e360.yale.edu. Retrieved 15 May 2019.
  29. ↑ Phillips, Aleks (14 November 2024). "Delhi shuts all primary schools as hazardous smog worsens". BBC News. Retrieved 31 January 2026.
  30. ↑ "Delhi has a new plan to fight its toxic air—but will it deliver?". healthpolicy-watch.news. Retrieved 29 April 2026.
  31. ↑ "Delhi air pollution fuels anger among residents". japantimes.co.jp. Retrieved 29 April 2026.
  32. ↑ "Delhi among top 10 most polluted cities in the world". iqair.com. Retrieved 29 April 2026.
  33. ↑ "pollution in Delhi, Delhi air quality and air pollution in India". Google Trends. Retrieved 12 April 2021.
  34. ↑ "Pollution in Delhi and pollution in Beijing". books.google.com. Retrieved 21 April 2021.
  35. ↑ "Pollution in Delhi". wikipediaviews.org. Retrieved 30 April 2021.
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