In winters, almost two-thirds of Delhi’s PM 2.5 pollution comes from outside city

Data for the study were derived from 10 days of air-quality monitoring in the winter and summer of 2016-17

- By Bhasker Tripathi

Delhi contributes no more than 36 percent to its fine-particulate (PM 2.5) pollution during winters, with 64 percent coming from sources outside the 56,800-sq-km area of the national capital region (NCR), according to a new study.

During the winter of 2016-17, the average concentration of PM 2.5 in Delhi-NCR was 168 microgram per cubic metre (μg/m3) — about three times higher than the national standard of 40 μg/m3 and about 16 times higher than the World Health Organisation’s (WHO) tighter standard of 10 μg/m3 , said the study released on 16 August 2018.

The average maximum concentration of PM 2.5 during winters was 254 μg/m3, while the minimum average concentration was 92 μg/m3, said the study by The Energy and Resources Institute (TERI) and the Automotive Research Association of India (ARAI).

Representational image. AP

Representational image. AP

Emitted when coal, kerosene, petrol, diesel, biomass (like wood and cow-dung) is burnt, PM 2.5 is about 30 times finer than a human hair. These particles can be inhaled deep into the lungs, causing heart attacks, strokes, lung cancer and respiratory diseases. Their measurement is considered to be the best indicator of the level of health risks from air pollution, according to the WHO.

In 2015, only one in 1,000 Indians lived in areas where particulate pollution did not exceed WHO annual safe levels for PM 2.5 of 10 µg/m3, IndiaSpend reported. In 2015, as many as 1.09 million deaths in India were attributed to PM 2.5 pollution, the report said.

17 percent Of Delhi’s winter PM 2.5 pollution comes from outside India

The NCR (excluding Delhi) — home to 27 million — adds 34 percent and regions outside the NCR (17 percent) India (13 percent) together contribute 30 percent to fine-particulate pollution in Delhi during winters, said the TERI & ARAI study, commissioned by the Ministry of Heavy Industries and Public Enterprises.

Sources Of PM 2.5 Pollution In Delhi, 2016-17
Sources Of Pollution Winters Summers
Delhi Itself 36% 26%
NCR Except Delhi 34% 24%
Upwind Region Outside NCR 17% 17%
Upwind Region Outside India 13% 33%

Source: The Energy And Resource Institute


During summers, however, 74 percent of Delhi’s PM 2.5 pollution is caused by sources located outside Delhi, which contributes only 26 percent to its pollution, the biggest source of which comes from outside India, said the report.

In the summer, the average concentration of PM 2.5 at all monitoring sites across Delhi-NCR was 90 μg/m3, more than two times the national safe levels or eight times higher than WHO levels, with PM 2.5 varying from 65 to 130 μg/m3, said the study.


“It is shocking how low Delhi’s contribution to the pollution is,” Ajay Mathur, director general, TERI, told the Times of India. “It shows that action is required not just in Delhi but in the entire NCR region and even beyond, particularly areas upwind of NCR.”

Data for the study were derived from 10 days of air-quality monitoring in the winter and summer of 2016-17 at nine stations in Delhi, four in Uttar Pradesh and seven in Haryana.

58 percent of Delhi’s PM 2.5 could be cut

In a business-as-usual scenario, which assumes all current policies–such as more efficient vehicle- and industrial-emission norms, more use of gas instead of cookstoves, cleaner brick kilns–are not strictly implemented, average PM 2.5 concentration in winter and summer seasons will rise by 8.25 percent over 14 years to 2030, from 109 μg/m3 to 118 μg/m3, according to the study.

Delhi can reduce 58 percent of its PM 2.5 pollution by 2030 if the government stops the use of biomass in NCR, and replaces high-ash coal in industries with agricultural stubble, the burning of which worsens pollution.

These steps would mean the end of biomass use in the NCR by greater use of gas in rural households, use of agricultural residues in power plants and other industries to replace the use of high-ash, polluting coal and enforcement of new, stricter PM 2.5 standards for industries, using solid fuels and more electric and hybrid vehicles.

The author is a principal correspondent with IndiaSpend. is a data-driven, public-interest journalism non-profit/ is fact-checking initiative, scrutinising for veracity and context statements made by individuals and organisations in public life.

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