This demands urgent and aggressive scaling up of the multi-sector action plan to control pollution
The last winter (2022-23) turned out to be the most polluted one for Maharashtra and Gujarat in the previous four years, revealed a new analysis by the Delhi-based non-profit Centre for Science and Environment (CSE).
The air quality (PM2.5) analysis for October 1, 2022 to February 28, 2023 has been carried out by CSE’s Urban Lab. In these states, winter pollution typically sets in during late November and early December, when the cooler and calmer conditions trap local pollution.
Also read: Delhi is India’s most polluted megacity, but others are catching up: CSE report
The average winter pollution level in the cities of Maharashtra rose by 13 per cent compared to the mean of the previous three winter seasons. Winter pollution has been rising in Maharashtra on a yearly basis and stood at 66 micrograms per cubic meter (µg/m³) this winter, the study found.
Fifteen cities that have been considered from the western states for assessment of the regional trend include Ahmedabad, Ankleshwar, Gandhinagar, Nandesari, Vapi, Vatva, Mumbai, Navi Mumbai, Pune, Aurangabad, Chandapur, Kalyan, Nasik, Nagpur and Solapur.
“The fact that the big cities as well as smaller towns have experienced the rise in winter PM2.5 levels points to the rapid spread of the air pollution problem in this region,” said Anumita Roychowdhury, executive director, research an advocacy, CSE.
Winter pollution has been on a decline in Gujarat since 2019, but it spiked up this winter. In absolute terms, Gujarat was the more polluted of the two states, with a winter average of 73 µg/m3. Gujarat registered an increase of 6 per cent compared to the mean of the previous three winters.
Avikal Somvanshi, senior programme manager, Urban Lab, CSE, told Down To Earth:
While in absolute terms, Gujarat has a higher pollution level, it is rising faster in Maharashtra. The region’s most polluted locations are Mumbai and Navi Mumbai. Vapi and Surat are among the most polluted locations in Gujarat. Nagpur registered the highest increase in pollution, with 105 per cent rise compared to the previous winter.
The regional influence of pollution is sharply evident in the synchronised spread of winter pollution across the cities. Worsening of air quality starts mid-October across western India in a synchronised fashion as the weather starts to cool down and winds slow down. But the analysis is hampered by poor data quality from the regional stations. Data for 96 days is missing from stations in Pune, while in Nandisari, data for 68 days is missing. There are large gaps in data from other stations as well.
Also read: This winter was the cleanest in NCR since 2018, finds CSE; Delhi air most toxic
“Even though there are multiple real time monitors in a few cities of these states, many could not be considered for long term analysis due to data gaps and lack of quality data. In several cases, the real time monitors have been set up recently and, therefore, long term data is not available,” said Somvanshi.
While local pollution is increasing in these rapidly motorising and developing cities, the regional influence further aggravates the challenge. This is overpowering the advantage of natural ventilation of the coastal climate. This demands an immediate roadmap to control pollution from the key sources across the region, Roychowdhury added.
Daily peaks of PM2.5 pollutants are growing faster in Gujarat, but it is a problem in Maharashtra as well, the analysis pointed out. Navi Mumbai and Vapi are the most polluted cities in these states.
Gandhinagar in Gujarat was the least polluted city with a PM2.5 average of 45 µg/m³. Solapur in Maharashtra also has a seasonal average of 45 µg/m³, but due to excessive gaps in data (36 days of missing data), this cannot be said with certainty. The same goes for the cities of Nandesari and Pune, which have a high quantum of missing data.
Nagpur, followed by Navi Mumbai, registered the highest increase in winter pollution, the document noted. Nagpur was the worst performer in terms of surge in pollution. The city registered an increase of 105 per cent compared to the preceding winter. Navi Mumbai followed it with 59 per cent increase. Winter pollution level in Vapi this season has been 38 per cent higher than the mean of the previous three winters.
However, Kalyan in Maharashtra showed the most improvement in air quality this season (23 per cent) compared to the corresponding period in the previous year. Pune follows it with 19 per cent, Ankleshwar with 18 per cent, Ahmedabad with 10 per cent and Vatva with 5 per cent improvement in PM2.5 levels compared to the previous year.
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Navi Mumbai’s Sector 19A monitoring station was the most polluted location among the cities of the two states with PM2.5 averaging 164 μg/m³.
Mumbai’s monitoring stations at Deonar, Bandra-Kurla Complex, Mazgaon, Navy Nagar, Chakala and Vile Parle West comprise six of the 10 most polluted locations in the two states. Surat in Gujarat also features among these 10 locations.
In 2022, there was a significant increase in the amount of NO2 concentration during November and December compared to October. NO2 comes entirely from combustion and significantly from vehicles. Kalyan in Maharashtra registered the greatest increase — three times the maximum build-up of NO2 between October and December.
In absolute concentration, Ahmedabad registered the highest average of 104 µg/m³. The pollution levels on Diwali night (8 pm-8 am) shot up by 1-5.9 times the average level recorded seven nights preceding Diwali.
Ahmedabad experienced 5.9 times higher PM2.5 level on Diwali night. Chandrapur in Maharashtra follows it. Mumbai and Nagpur had the least polluted Diwali night in the region, with 70 and 75 µg/m³, respectively, followed by Nashik with 85 µg/m³.
This analysis is part of the third edition of Urban Lab’s Air Quality Tracker Initiative, which started in the winter of 2020-21. It is based on the real-time data available from the current working air quality monitoring stations in these two states. The analysis covers 58 continuous ambient air quality monitoring stations spread across 17 cities in two states.
“The rapidly growing cities of the western states of Maharashtra and Gujarat that were hitherto not so much under the scanner for growing air pollution problem, are increasingly coming under the spotlight. Winter pollution is indicative of the growing local problem. As soon as the weather turns adverse with cool and calm conditions, the high local pollution gets trapped and spirals,” Roychowdhury said.
This demands urgent and aggressive scaling up of the multi-sector action plan to control pollution from vehicles and transport, industries, open burning of waste and landfill fires, use of solid fuels in households, construction and dust sources, she added.
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The average winter pollution level in the cities of Maharashtra rose by 13 per cent compared to the mean of the previous three winter seasons. Representative photo: iStock..png)
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