<p>Delhi's PM2.5 pollution average for the July-August-September quarter this year stood at 37 microgram per cubic metre, only marginally higher than the five-year low of 36 microgram per cubic metre recorded during 2020, according to an analysis by the Centre for Science and Environment (CSE).</p>.<p>Pollution levels in the July-August-September quarter were preceded by one of the most polluted summers this year, unlike in 2020 when the trimester followed the cleanest ever summer (March-May) due to extraordinary conditions created because of hard <a href="https://www.deccanherald.com/science-and-environment/study-suggests-children-s-eyesight-may-have-worsened-in-lockdown-1031668.html" target="_blank">pandemic lockdowns</a>, the green think tank said.</p>.<p>"Therefore, it is important to understand what aided in cleaning up the Delhi air. Looking at the rainfall data it becomes evident that distribution of rainfall has a relatively higher impact on seasonal air quality than the absolute quantity of rainfall," it said.</p>.<p>There have been 45 rainy days in July, August and September this year as compared to just 39 rainy days in the quarter last year.</p>.<p>"These six extra rainy days helped keep the seasonal average low despite total rainfall this monsoon having been just one-third of the previous monsoon," the CSE said.</p>.<p>These additional rainy days also pushed the regular start of bad air quality days further down the month of October, it said.</p>.<p>The PM2.5 average for the quarter stood at 38 microgram per cubic metre in 2021, 41 microgram per cubic metre in 2019 and 43 microgram per cubic metre in 2018.</p>.<p>The CSE had on Thursday said the average PM2.5 pollution in Delhi in the winter season has declined by about 20 per cent as compared to the pre-pandemic period.</p>.<p>The PM2.5 concentration for winter (October 1 to February 28) used to hover around 180-190 microgram per cubic metre before the pandemic. It has come down to 150-160 microgram per cubic metre since then, it said.</p>.<p>However, the seasonal average is still over 150 per cent above the 24-hour standard (60 microgram per cubic metre) and almost four times the annual standard (40 microgram per cubic metre) despite the improvement, the green think tank noted.</p>
<p>Delhi's PM2.5 pollution average for the July-August-September quarter this year stood at 37 microgram per cubic metre, only marginally higher than the five-year low of 36 microgram per cubic metre recorded during 2020, according to an analysis by the Centre for Science and Environment (CSE).</p>.<p>Pollution levels in the July-August-September quarter were preceded by one of the most polluted summers this year, unlike in 2020 when the trimester followed the cleanest ever summer (March-May) due to extraordinary conditions created because of hard <a href="https://www.deccanherald.com/science-and-environment/study-suggests-children-s-eyesight-may-have-worsened-in-lockdown-1031668.html" target="_blank">pandemic lockdowns</a>, the green think tank said.</p>.<p>"Therefore, it is important to understand what aided in cleaning up the Delhi air. Looking at the rainfall data it becomes evident that distribution of rainfall has a relatively higher impact on seasonal air quality than the absolute quantity of rainfall," it said.</p>.<p>There have been 45 rainy days in July, August and September this year as compared to just 39 rainy days in the quarter last year.</p>.<p>"These six extra rainy days helped keep the seasonal average low despite total rainfall this monsoon having been just one-third of the previous monsoon," the CSE said.</p>.<p>These additional rainy days also pushed the regular start of bad air quality days further down the month of October, it said.</p>.<p>The PM2.5 average for the quarter stood at 38 microgram per cubic metre in 2021, 41 microgram per cubic metre in 2019 and 43 microgram per cubic metre in 2018.</p>.<p>The CSE had on Thursday said the average PM2.5 pollution in Delhi in the winter season has declined by about 20 per cent as compared to the pre-pandemic period.</p>.<p>The PM2.5 concentration for winter (October 1 to February 28) used to hover around 180-190 microgram per cubic metre before the pandemic. It has come down to 150-160 microgram per cubic metre since then, it said.</p>.<p>However, the seasonal average is still over 150 per cent above the 24-hour standard (60 microgram per cubic metre) and almost four times the annual standard (40 microgram per cubic metre) despite the improvement, the green think tank noted.</p>