Cities in India’s eastern states are increasingly falling into the pincer grip of toxic particulate pollution during winter season – and the problem is spreading quickly to the smaller cities and towns of the region: says a latest assessment by Centre for Science and Environment (CSE) released on Tuesday.
The assessment also notes that though the bigger cities in the region – like Patna and Kolkata — that are part of the National Clean Air Programme (NCAP), have witnessed a marginal improvement in the winter average of their PM2.5 levels compared to the previous two winters, their levels are still high.
The smaller towns of Bihar — Begusarai, Bettiah and Siwan in particular — have recorded the worst winter air in the region, with their seasonal average exceeding 200 microgram per cubic metre (µg/m³). Nitrogen dioxide (NO2) pollution is also high in the cities and towns of the region, with Arrah in Bihar recording a staggering 113 µg/m³ monthly average for November, notes CSE.
“This analysis is a stark reminder of the rapid spread of pollution. More cities and smaller towns are scaling the pollution height and dotting the pollution map. This once again vindicates the need for a strong state-wide and regional management of air pollution. This is needed to control local pollution sources including vehicles, industry, open burning and construction dust, as well as the impact of upwind pollution sources on downwind cities and towns,” says Anumita Roychowhdury, executive director, research and advocacy, CSE.
“Additionally, data gap is also a challenge in the region. Even though the real time monitors have increased in the region including in Jharkhand, some of these could not be used due to data gaps and quality issues. Some of these are new and therefore long term data is not available. The data, thus, is indicative of the current status and seasonal variation in particulate pollution in medium and smaller cities,” says Avikal Somvanshi, senior programme manager, Urban Lab, CSE.
With the winter season coming to an end, the Urban Lab at CSE has analysed air quality trends during the winter months (October 2022 to February 2023) in cities of the eastern states of West Bengal, Bihar and Odisha. This is an assessment of seasonal trends in PM2.5 concentration for the period October 1, 2022 to February 28, 2023 for 2019, 2020, 2021, 2022 and 2023. Winter inversion and cool and calm conditions trap local pollution that is already high. This is part of the third edition of the Urban Lab’s Air Quality Tracker Initiative since 2020-21.
This analysis covers 50 continuous ambient air quality monitoring stations (CAAQMS) spread across 32 cities in the three states:
- West Bengal: seven stations in Kolkata, three in Howrah, and one each in Asansol, Siliguri, Durgapur and Haldia. Real time monitors in Durgapur and Haldia became operational only by the end of 2020.
- Bihar: Six stations in Patna, three each in Gaya and Muzaffarpur, two in Bhagalpur, and one each in Hajipur, Bettiah, Bihar Sharif, Darbhanga, Motihari, Araria, Arrah, Chhapra, Katihar, Kishanganj, Manguraha, Munger, Purnia, Rajgir, Saharsa, Sasaram, Siwan, Aurangabad, Begusarai and Samastipur
- Odisha: One real time station each in Talcher and Brajrajnagar. Many new stations have been added in November 2022 — one station each in Baripada, Bileipada, Keonjhar, Nayagarh, Rairangpur, Rourkela, Suakati and Tensa.
Only a limited long term trend analysis has been possible for the cities that have added stations and monitors relatively recently (like some of the cities in Odisha). Jharkhand has no working monitoring stations, and hence, offers no PM2.5 data for the last two years – which is why its cities have not been included in this analysis.
This analysis is based on the real time data available from the current working air quality monitoring stations in east India. Somvanshi says a huge volume of data points have been cleaned and data gaps addressed based on the United States Environmental Protection Agency (USEPA) method for this analysis.
