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The winter of 2022-2023 was the cleanest for Delhi-National Capital Region (NCR) since 2018, when large-scale air quality monitoring started, according to a new analysis by New Delhi-based non-profit Centre for Science and Environment.
This winter was the first in the last five years when both Diwali and late December (around Christmas) did not experience a smog episode. Delhi-NCR saw the lowest particulate matter (PM) 2.5 average in the last five years — but still has a long way to go to meet clean air benchmarks.
Delhi was the most polluted out of all five major NCR cities, CSE found. There were 10 days of city-wide average in “severe” or worse AQI category, which was much lower compared to 24 such days in the previous winter and 33 in 2018-19 winter.
The report said:
A comprehensive analysis of PM2.5 trends during the entire winter season (October 2022-January 2023) in Delhi-NCR shows a bending of the winter pollution curve and lowering of peak levels.
The Urban Lab at CSE found a continuous drop in average seasonal levels of air pollution, although elevated levels prevailed at city stations. Meteorology and emergency action based on pollution forecasting helped improve air quality. Heavy and extended rainfall in the early phases of the season also prevented smog episodes.
The winter also saw fewer stubble-burning episodes — 43 per cent according to United States National Aeronautics and Space Administration’s VIIRS satellite and 49 per cent lower according to NASA’s MODIS satellite — than last year.
“This downward trend will have to be sustained with much stronger action on vehicles, industry, waste burning, construction, solid fuel and biomass burning to meet the clean air standard,” said Anumita Roychowdhury, executive director-research and advocacy at CSE.
Delhi and the neighbouring cities of Faridabad, Ghaziabad, Gurugram and Noida were relatively more polluted than other NCR towns, though not significantly.
Delhi was the most polluted city in NCR followed by Greater Noida this winter. But Dharuhera and Baghpat, much smaller towns, were next on this worst polluted list, placed above the much larger cities of Faridabad, Gurugram and Ghaziabad.
Mandikhera and Palwal were the least polluted towns in the NCR with their winter average settling below 40 microgramme per cubic metre (µg/m³).
Likewise, Delhi registered the highest peak city-wide pollution with a 24-hour average at 401 µg/m³, followed by Gurugram at 385 µg/m³ and Baghpat at 368 µg/m³. Palwal’s peak of 78 µg/m³ was the lowest in NCR.
The city-wide winter average for Delhi stood at 160 µg/m³ for October-January. The national capital’s pollution levels peaked at 401 µg/m³ on November 3, 2022. This was 26 per cent lower than the highest recorded winter peak — 546 µg/m³ in the winter of 2019-20.
Even though peak pollution levels showed a downward trend, the air pollution is is above the permissible levels.
There was just one smog episode this time, lasting January 6-9, 2023. There was also an improvement in 32 out of 36 Continuous Ambient Air Quality Monitoring Stations in their seasonal averages over the average of the last three years. However, pollution levels still remained very high across all stations.
“The only way to prevent the high peaks and smog episodes during winter is to ensure sustained improvement in air quality to meet the national ambient air quality standard across the region,” CSE said.