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Pollution Bouncing Back In Odisha, Bihar and West Bengal: Study

New Delhi: Odisha along with Bihar and West Bengal is now feeling the sting of increased winter air pollution, a new analysis of regional pollution trends by the Centre for Science and Environment (CSE) has revealed.

The winter smog that engulfs North India during early November begins to extend eastwards during late December and early January. Bihar, West Bengal and Odisha are affected mostly during this time when winter inversion and the cool and calm conditions trap the local pollution that is already high.

“This analysis of real-time air quality data for the period 2019-2021 shows that the downward dip in the pollution that was induced by the hard lockdown phases of the pandemic in 2020 is threatening to bounce back with the levels in 2021 already rising. But in many cases, the levels are still lower than in 2019. This underscores the urgency of scaling up action across all sectors to prevent further worsening and to arrest the trend in this region,” said executive director, research and advocacy at CSE, Anumita Roychowdhury.

“Even though real time air quality monitoring has begun to expand in these states to provide more up to date and real-time information on air quality, there are serious concerns around missing data and gaps that makes proper risk assessment difficult. In some stations of Bihar and Odisha, data availability is so low that the trend cannot be assessed. Quality control of data is necessary,” said programme manager at Urban Data Analytics Lab, CSE, Avikal Somvanshi.

This new analysis of real-time pollution data by CSE is a part of the air quality tracker initiative of the Urban Data Analytics Lab of CSE. The objective is to understand the trend and magnitude of pollution in different regions that have real-time air quality monitoring systems. This is an assessment of annual and seasonal trends in PM2.5 concentration for the period January 1, 2019, to January 4, 2022. This analysis is based on the real time data available from the current working air quality monitoring stations. A huge volume of data points have been cleaned and data gaps have been addressed based on the USEPA (United States Environment Protection Agency) method for this analysis.

This analysis covers 29 continuous ambient air quality monitoring stations (CAAQMS) spread across 12 cities in the three states: West Bengal — seven stations in Kolkata, three stations in Howrah, and one station each in Asansol, Siliguri, Durgapur, Haldia; Bihar – six stations in Patna, three stations in Gaya, three stations in Muzaffarpur and one in Hajipur; Odisha — one real-time station each in Talcher and Brajrajnagar.

Since Odisha has very limited real-time monitoring, the data is indicative of the current status of air quality and seasonal variation in particulate pollution in medium and smaller cities.


Most cities show a rising trend in annual PM2.5 levels after an initial drop during 2020 with more pandemic related lockdown phases

Except for Bajrajnagar and Talcher in Odisha,

Nearly all cities in the region show a drop in annual average PM2.5 level in 2020 that was also the year with maximum lockdown phases. There was a rebound and 2021 saw a rising trend once again though in several cases the levels are lower than in 2019.

Durgapur, a big industrial hub of West Bengal that is also designated as a critically polluted area by CPCB, has the most polluted air in the region with a 2021 average of 80 ug/m3. This is followed by Muzaffarpur and Patna with a 2021 annual average of PM2.5 at 78 ug/m3 and 73 ug/m3 respectively.

If the real-time data is taken as an indicator, in West Bengal, Durgapur needs to reduce annual average PM2.5 by 50 per cent to meet the annual PM2.5 standard, Howrah 34 per cent, Asansol 32 per cent, Siliguri 32 per cent, Kolkata 28 per cent. Haldia met the standard in 2021.  In Bihar, Muzaffarpur needs a reduction in the annual average PM2.5 level by close to 49 per cent to meet the standard, Patna 45 per cent, Hajipur 33 per cent, Gaya 18 per cent.

Odisha is the only state where Bajrajnagar and Talcher have met the annual standard with average.

Winter pollution can be a toxic cocktail of particulate and gases

There is a significant increase in the amount of nitrogen dioxide (NO2) in the air of all cities of eastern states during December compared to the previous months of November, October and September.

Brajrajnagar registered 3.6 times jump in monthly NO2 level, Kolkata registered a 2.8 times increase while Patna, Talcher, and Asansol registered a 2.5 times increase.

In absolute concentration term, Patna registered the highest monthly average of 51 µg/m3 for December. It is followed by Kolkata (50 µg/m3) and Talcher (44 µg/m3). Muzaffarpur, Howrah and Hazipur showed an increase in the amount of NO2 in the month of November as compared to December.