Delhi's smoggy winter: 64% fine-particulate pollution comes from outside

Delhi contributes no more than 36 per cent to its fine-particulate (PM 2.5) pollution during winters, with 64 per cent 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 Organization’s (WHO) tighter standard of 10 μg/m3 , said the study, released on August 16, 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).

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.