Air Pollution

Genesis of the Delhi Air Pollution and its mitigation


From UPSC perspective, the following things are important :

Prelims level: Read the attached story

Mains level: Delhi Air Pollution issue


As the situation becomes an annually recurring one in New Delhi and NCR, here’s a look at how far back it goes and what policies have been adopted by the Centre and Delhi’s elected governments to curb air pollution over the years.

Do you know?

In November 2016, in an event known as the Great Smog of Delhi, the air pollution spiked far beyond acceptable levels. This tagged New Delhi to be world’s most polluted city ever.

Causes of Poor Air Quality

  • Motor vehicle emissions are one of the causes of poor air quality.
  • Badarpur Thermal Power Station, a coal-fired power plant was another major source of air pollution in Delhi.
  • 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)
  • Fires in Bhalswa landfill is a major reason for airborne particles in Delhi.
  • Burning of effigies during Vijayadashami and bursting of firecrackers burning during Diwali is often accused by the left-wing activists to cause of Delhi’s poor air quality.
  • 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.

Evolution of policies

(1) Recognition of the broader issue (1995)

  • In March 1995, the Supreme Court, while hearing a plea by environmentalist and lawyer M.C. Mehta about Delhi’s polluting industries
  • It noted that Delhi was the world’s fourth most polluted city in terms of concentration of suspended particulate matter (SPM) in the ambient atmosphere as per the WHO’s 1989 report.

(2) Identifying major pollutants (1996)

  • The Court took note of two polluting factors — vehicles and industries.
  • In 1996, the court ordered the closure and relocation of over 1,300 highly-polluting industries from Delhi’s residential areas beyond the National Capital Region (NCR) in a phased manner.
  • In 1996, Mr. Mehta filed another public interest litigation (PIL) alleging that vehicular emissions were leading to air pollution and that it posed a public health hazard.

(3) Action plan by Delhi Govt. (1996)

  • The Delhi government submitted an action plan to the apex court.
  • The court recognised the need for technical assistance and advice in decision-making and implementation of its orders.

(4) Establishment of EPCA (1998)

  • The Supreme Court asked the Environment Ministry to establish an authority for Delhi, leading to the creation of the Environmental Pollution Control Authority of Delhi NCR (EPCA) in 1998.
  • The EPCA submitted its report containing a two-year action.
  • The Court subsequently ordered the Delhi Transport Corporation (DTC) bus fleet, taxis, and autos to switch to Compressed Natural Gas (CNG), and the phasing out of all pre-1990 autos.
  • Coal-based power plants within Delhi were also converted to gas-based ones.

(5) National Air Quality Programme (NAMP)

  • Around the same time, the Centre decided to establish a network of monitoring stations under the National Air Quality Programme (NAMP) to measure key pollutants.
  • The NAMP monitors the four major pollutants as part of the AQI – sulphur dioxide, oxides of nitrogen, respirable particulate matter and fine particulate matter.
  • It also checks wind speed and direction along with relative humidity and temperature.

How were air quality standards revised?

  • The National Ambient Air Quality Standards (NAAQS) were specified by the Central Pollution Control Board (CPCB).
  • It identified pollutants like PM10 (particulate matter with a diameter exceeding 10 microns), sulphur dioxide and nitrogen oxides were measured.
  • The NAAQS were revised in 2009 to include 12 categories of pollutants including PM2.5 (particulate matter with a diameter under 2.5 microns
  • Particulate Matter (PM) is primarily generated by fuel combustion from different sectors, including transport, energy, households, industry and agriculture.

Arriving finally at: Graded Response Action Plan (GRAP)

  • According to the revised NAAQS, the acceptable annual limit for PM2.5 is 40 micrograms per cubic metre (ug/m3) and 60 ug/m3 for PM10.
  • In the winter of 2016, Delhi witnessed one of its worst incidents of pollution-induced smog, with PM2.5 and PM10 levels reaching a whopping 999 ug/m3 in parts of Delhi on November 1.
  • Subsequently, the Supreme Court in November 2016 told Delhi and NCR authorities to form a plan to deal with the air pollution.
  • The MoEFCC in early 2017 came out with the Graded Response Action Plan (GRAP).


Try this question from CS Mains 2015:

Q.Mumbai, Delhi and Kolkata are the three megacities of the country but the air pollution is a much more serious problem in Delhi as compared to the other two. Why is this so?


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