Delhi lockdown pollution higher in 2021: Study

NEW DELHI: The lockdown imposed this year on account of the second wave of Covid-19 was not as effective in bringing down the pollution levels in the national capital as it was last year, showed an air quality analysis conducted by the Delhibased think tank Centre for Science and Environment (CSE).

“Lockdowns were effective in bringing down PM2.5 levels this year as well. But given the shorter duration and lesser stringent lockdown this year, the levels are not as low as summer 2020,” read the analysis by CSE.

The think tank said that the imposition of a partial lockdown (from April 6 to April 19) lowered PM2.5 levels by 20% in Delhi, while the complete lockdown (from April 20 onwards) brought the average pollution levels further down by 12%.

“Meteorology would be partly responsible for this elevated level but this could also be a reflection of weakening of pollution control measures and efforts in the city and region during the pandemic phase. Traffic intensity was also comparatively higher,” the analysis added.

The report said the monthly average level of PM2.5 in April and May this year, which was the phase when hard lockdown was imposed in the Capital, was higher compared to April-May 2020 -- a period which was marked by a strict nationwide lockdown.

It said the evening peak of the hourly cycle of NO2 was 29% higher during this year’s lockdown as compared to the lockdown last year. However, it was still 57% lower than the regular evening peak noted in May of 2019.

“The key highlight is that during spring time, January to March, when pollution level begins to subside after winter, PM2.5 this year has recorded the highest seasonal levels compared to the corresponding period in preceding years, including 2019 which was a normal year,” said Avikal Somvanshi, programme manager in CSE’s urban lab team of the sustainable cities programme.

“...despite the partial restrictions, pollution levels have increased. While the reason needs investigation, it is important to understand that there would be a rebound effect with the full opening of the economy,” said Anumita Roychowdhury, executive director (research and advocacy), CSE. The CSE analysis also showed that there were 27 ”very poor” days in terms of air quality this February-March compared to 17 last year and 12 in 2019.