Number of days with severe or worse air quality bounced back to pre-Covid levels in Delhi: CSE report

An analysis of winter air pollution trends, released by CSE, highlighted that despite the stabilised trend in average levels, Delhi still had the highest number of 'severe' or 'worse' air quality days compared to other big cities in NCR. Details here.

Number of days with severe or worse air quality bounced back to pre-Covid levels in Delhi: CSE report

Photo: @CSEIndia

Though there has been a minor drop in the seasonal level of air pollution compared to previous winters, in Delhi-NCR, the level is "extremely high, and far from meeting the safety standard," an analysis of winter air pollution trends in Delhi-NCR by Centre for Science and Environment (CSE) pointed out.

"Even though there is considerable variation in seasonal averages across the region, winter pollution episodes are alarmingly high and synchronised in the region despite large distances. This is the challenge of this landlocked region. Despite being the wettest winter, the overall winter average of PM2.5 has stayed elevated and the overall contribution of the local and regional sources are higher than that from stubble-smoke," said Avikal Somvanshi, programme manager, Urban Lab Analytics, CSE.

The analysis that was released on March 30 by the Delhi based research and advocacy organisation also highlighted that the contribution of stubble smoke intensified post-Diwali due to concentrated burning but no-stubble sources accounted for almost 80 per cent of the seasonal average levels.

The analysis was based on real-time data from monitoring stations in Delhi-NCR for the entire winter period, from October 1, 2021 to February 28, 2022. It noted that despite heavy and prolonged rains in different phases this winter, long smog episodes and elevated levels have prevailed in the capital.

Also Read: Severe peak in winter smog expected in Delhi, quick action required to counter this: CSE Report

"Marginal improvement in Delhi's air quality despite the wettest winter in over a century"

The analysis also added that the region had recorded a few days of satisfactory air quality in January which has not happened in the previous three seasons. This change was attributed to unprecedented heavy rainfall and the lockdown imposed on the city to control the Omicron-wave of the pandemic in January.

The city-wide winter average for Delhi stood at 172 microgramme per cubic metre (μg/m3), which was identical to the seasonal average of the winter of 2019-20 but is 9 per cent lower than the seasonal average of the 2020-21 winter. The seasonal peak was about 5 per cent lower than both preceding winters, the analysis said.

According to CSE, 25 days of the 2021-22 winter had the city-wide average in 'severe' or 'worse' AQI (air quality index) category -- up from 23 such days in the previous winter and at par with 25 days in the winter of 2019-20. The city also saw two days of 'good' air and seven days of 'satisfactory' air this winter, which is an improvement from the last winter season when no such low pollution days were recorded, the analysis observed.

Also Read: 'Air pollution shortening lives by about 10 years in Delhi and UP'

As per the Central Pollution Control Board (CPCB), an air quality index between 301 and 400 is considered 'very poor', and can cause 'respiratory illness upon prolonged exposure.'

Smog episodes

Talking about the smog episodes that the capital witnessed, the analysis pointed out that the 2021-22 winter witnessed smog episodes that lasted 10 days -- longer than the longest Diwali smog episodes recorded in the previous three winters. Smog episodes in 2018-19, 2019-20, and 2020-21 lasted six days, eight days, and seven days, respectively. The intensity of this year's main smog episode was about 10 per cent lower than the intensity of the main smog episodes of the previous two winters.

This final analysis of winter pollution in Delhi and NCR concluded that there is a risk of pollution bouncing back with the reopening of the economy and increased traffic intensity post-hard lockdown phases. High winter pollution only indicates the magnitude of local and regional pollution that gets easily trapped when winter conditions turn cool and calm with a deepening of inversion.

Also Read: Environment ministry assures India will revise its air quality standards

"This requires strong action to introduce clean energy across all sectors, transformation of urban commuting with upscaled public transport, walking and cycling infrastructure and vehicle restraint measures and long distance freight management, and complete recycling of all waste streams through a strong infrastructure for material recovery," said Anumita Roychowdhury, executive director, research and advocacy, CSE.

She also added that the region needed performance-based action to ensure clean air standards are met in a time-bound manner.

delhi pollution #Air quality index #DelhiSmog #story #CSE 

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