Winter air poor despite rain

Despite its wettest winter in several decades, the Capital only saw a marginal reduction in pollution this time around as compared to last year, according to the Centre for Science and Environment (CSE).

Despite recording its wettest winter in the last several decades, Delhi only saw a marginal reduction in pollution this time around as compared to last year, found an analysis released by the Centre for Science and Environment (CSE) on Wednesday.

Delhi recorded 217mm of rainfall during this winter period -- nearly double of the 114mm recorded in the previous winter. (HT Photo)

Analysing a five-month period from October 1, 2021, to February 28, 2022, the city-wide average PM 2.5 level was found to be 172 microgramme per cubic metre (μg/m3) -- over four times the national annual standard of 40μg/m3 and the daily standard of 60μg/m3.

This is 9% lower than the seasonal average during the corresponding period in 2020-21 (189μg/m3), and similar to the pollution level in 2019-20 (173μg/m3).

The 2018-19 winter saw an average PM2.5 level of 190μg/m3.

The analysis also found the seasonal peak PM 2.5 level (516μg/m3) to be 5% lower than in 2020-21 (542μg/m3) and 2019-20 (549μg/m3).

“Meteorologically, this winter was the wettest in recent years with almost two-three fold more rainfall compared to previous winters, bulk of which happened in January, making it the least polluted January since real-time air quality monitoring started in the city. But, this meteorological advantage did not give much reprieve to the city as a rapid build-up in between rainy spells and formation of smog episodes during the rainless periods kept overall seasonal average very high,” said the analysis.

The Capital was 74mm during the 2019-20 winter and 86mm in 2018-19 winter.