New Delhi (NVI): Most polluted cities this winter were in Delhi-NCR and Uttar Pradesh, according to the Centre for Science and Environment (CSE) analysis of winter air pollution levels and trends.
In fact, eight of the top 10 were UP cities with Ghaziabad and Bulandshahr taking the top spots. Delhi at number five and Bhiwadi in Rajasthan at number 10 were the only exceptions, says the CSE report.
The analysis indicated that smaller towns saw higher winter pollution levels than mega cities. CSE carried out extensive analysis of real time data from cities in different regions to throw light on the difference between 2020-21 winter and the previous winters. This has been a special winter that coincides with the unlocking of the economy post pandemic linked hard lockdown phases, as per the report.
Cities otherwise with lower annual average level of PM2.5 can experience ugly spikes due to the trapping of pollution at a regional scale during winter, the analysis found.
It also indicated that uneven rise and fall across monitoring locations within a city and between contiguous cities and towns indicate higher impact of local pollution sources when meteorology turns adverse during winter.
A new focus of this analysis was on cities of the north-eastern region that showed lower averages but higher toxicity as the share of PM2.5 in PM10 is considerably high.
The CSE report said that winter pollution is only an indicator of what is going wrong across regions. To curb it, overall annual average levels have to reduce substantially on a year-on-year basis. This demands clean air action at scale and speed across all regions, it said.
“Winter is a special challenge when inversion, and cool and calm weather traps and spikes daily pollution. While the northern Indo Gangetic Plain is most affected, other regions also experience a rise, but with lesser intensity. But this year even though the average level of PM2.5 during summer and monsoon months was considerably lower than the previous year due to the summer lockdown, the winter PM2.5 concentration has risen compared to 2019 winter in many cities across regions.
“This bouncing back of pollution post-lockdown unmasks the high impacts of local and regional pollution. This demands quicker regional reforms to curb pollution from vehicles, industry, power plants and waste burning to curb the winter pollution and also sustain annual improvement at a regional scale with speed,” says Anumita Roychowdhury, CSE’s executive director in charge of research and advocacy.
“This analysis has considered 99 cities where data availability for two consecutive winters meets the minimum criteria of 75 per cent of data completeness requirement. This analysis has helped to understand the regional differences in regional profile of winter pollution. Even though there is considerable regional variation, peak pollution episodes increased and synchronized within the regions during winter. At the same time, uneven rise across monitoring locations and contiguous cities bring out the impact of local pollution,” says Avikal Somvanshi, programme manager in CSE’s Urban Lab team of the Sustainable Cities programme.
The analysis is part of the air pollution tracker initiative of CSE. It is based on publicly available granular real time data (15-minute averages) from the Central Pollution Control Board’s (CPCB) official online portal Central Control Room for Air Quality Management, CSE said in a statement.
The data is captured from 248 official stations under the Continuous Ambient Air Quality Monitoring System (CAAQMS) spread across 115 cities in 22 states and union territories. CAAQMS has many more cities in its network than included in the analysis, it said.
The CSE analysis of PM2.5 data shows that while some cities have witnessed arresting or stabilisation of trends with small variation, others have experienced either increase or decrease. North Indian cities are on average the most polluted in the country, over three times the average of South Indian cities, it said.
-ARK
