Around 64 per cent Delhi’s pollution comes from outside: CEEW


New Delhi: The number of “sever” plus “very poor” air quality during the winter has not decreased in the last three years, said the new study revealed by the public policy think tank Council on Energy,Environemnt and Water, (CEEW) on Friday.

During the three months of winter of 2021 (15 October 2021 – 15 January 2022), about 75 per cent of the days, air quality were in the ‘Very poor’ to ‘Severe’ category.

“Interestingly, despite more farm fire incidents in Punjab, Haryana, and Uttar Pradesh in 2021 compared to 2020, Delhi’s PM2.5 concentration during the stubble burning phase (i.e 15 October to 15 November) was lesser in 2021” the report said.

This was primarily due to better meteorological conditions like higher wind speed and more number of rainy days during this period.

The report talked about Regional influence predominant; Transport, dust, and domestic biomass burning are the largest local contributors to air pollution.

“We find that about 64 per cent of Delhi’s winter pollution load comes from outside Delhi’s boundaries. Biomass burning of agricultural waste during the stubble burning phase and burning for heating and cooking needs during peak winter are estimated to be the major sources of air pollution from outside the city”.

Locally, transport (12 per cent), dust (7 per cent), and domestic biomass burning (6 per cent) contribute the most to the PM2.5 pollution load of the city.

It added that the transport and dust are perennial sources of pollution in the city, the residential space heating component is a seasonal source.

However, this seasonal contribution is so significant that as the use of biomass as a heat source in and around Delhi starts going up as winter progresses, the residential sector becomes the single-largest contributor.

“This indicates the need to ramp up programmes to encourage households to shift to cleaner fuels for cooking and space heating” the report said.

The report stressed upon the need to focus on to focus on improving air quality forecasting systems, pointing out that these helped prevent extremely severe air pollution episodes in Delhi last winter.

Based on the forecasts, short-term emergency measures, such as halting operations of power plants, construction activities and plying of trucks, were introduced.

However, the report said to further reduce high air pollution episodes next winter, such systems would need to provide more accurate predictions of PM2.5 concentration levels.

“The findings reinforce the need for strengthening long-term and emergency actions aimed at curbing emissions. Additionally, with multiple forecasting systems, efforts should be made to encourage dialogue between various scientific groups and reconcile differences in varying estimates,” said Tanushree, programme lead, CEEW.

The report said the forecasts picked up the pollution trend but could not predict high pollution episodes.

“The availability of multiple forecasts provides decision-makers with a range of options. At the same time, this is an obstacle to effective on-ground action. To streamline the flow of information from forecasters to decision-makers, it is important to analyse the forecasts and assess their reliability. We found all the forecasts identified pollution trends accurately but accuracy decreases over time,” it said.

On the implementation of Graded Response Action Plan (GRAP) the report said it must be based strictly on modelled source contributions obtained from forecasts and timed accordingly.

This will eliminate the need for ad-hoc emergency directions to restrict various activities. For instance, restrictions on private vehicles can be brought in when the air quality is forecasted to be ‘Very poor’ as transport is a significant contributor.


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