This story is from October 23, 2021

Delhi: Average PM2.5 level for monsoon, pre-winter season lowest in 4 years

An analysis done by Centre for Science and Environment (CSE) says the average PM2.5 concentration of monsoon and pre-winter season (July 1 to October 15) was lowest in 2021 compared with the last four years.
Delhi: Average PM2.5 level for monsoon, pre-winter season lowest in 4 years
It can be expected that smog might have higher peak pollution this year if special steps are not taken to reduce the pollution from the sources. (File photo)
NEW DELHI: An analysis done by Centre for Science and Environment (CSE) says the average PM2.5 concentration of monsoon and pre-winter season (July 1 to October 15) was lowest in 2021 compared with the last four years.
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However, a delayed start of winter with multiple spurts of rain, as seen in 2019-20, is similar to the conditions prevailing this year. It can be expected that smog might have higher peak pollution this year if special steps are not taken to reduce the pollution from the sources.

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As Delhi recorded excess rainfall, it resulted in the cleanest monsoon in the last four years. The city-wide average for the monsoon and pre-winter season this year stood at 41 micrograms per cubic metre (ug/m3), with 96 days meeting the 24-hour standard for PM2.5. There was a progressive increase in the number of cleaner days with an average 6% annual improvement since 2018, said CSE.
Though winter began on October 15 at a cleaner level, CSE’s analysis stated that 2021-22 might have higher peak pollution. “On average, the 2020-21 winter season was 5% worse among the major NCR cities and Delhi compared with last year, but the peak pollution on average was 13% lower,” it added.

“Even though the average level during 2019-20 was lesser than other winters, the peak daily pollution was considerably higher across all major NCR cities. This can be attributed to September and October rainfall that pushed and concentrated the farm stubble burning towards the end of October and start of November when winter conditions were turning more adverse,” CSE’s report further stated.
Anumita Roychowdhury, executive director, research and advocacy, CSE, said, “The winter of 2021 is starting with a cleaner threshold compared with the previous years, largely due to the intense and prolonged effect of the monsoon. While winter pollution cannot be predicted at this moment, the evidence of rising summer pollution in 2021 despite the lockdown and the evidence of a synchronised effect of winter pollution across the Indo-Gangetic Plain add to our concern. How soon and intensely the winter pollution will hit us will depend on the scale and speed of action across the region and leveraging it for more sustained air quality gains.”
However, summer 2021 was more polluted as the seasonal average rose to 79 ug/m3 and the number of days meeting the prescribed standard was 51, as against 90 in 2020. “PM2.5 levels this summer have almost returned to the 2019 levels despite the partial lockdowns,” mentioned the report.
The report also said that particulate pollution dominated the daily pollution in Delhi during pre-winter season (September 1 to October 15), but other gaseous pollutants, like ozone and carbon monoxide, had become the lead pollutants along with particulate pollution of the day due to washout effect of rain.
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