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Post-Diwali air quality data reveals severe pollution in Maharashtra's inland cities like Pimpri Chinchwad, while Mumbai maintained better levels due to favorable sea winds. Meanwhile, the CPCB has capped PM2.5 readings at 1,000 μg/m³ for AQI calculations, citing a focus on prolonged exposure over momentary spikes.
The Post-Diwali Air Quality Crisis in Maharashtra
The aftermath of Diwali has once again brought the critical issue of air pollution in Maharashtra into the spotlight. While national attention often centers on Mumbai’s air quality, recent data from the Central Pollution Control Board (CPCB) reveals that inland cities in the state experienced significantly more severe conditions. On November 9, thirteen cities across Maharashtra were classified within the ‘poor’ or ‘very poor’ air quality categories, signaling a widespread environmental challenge that extends far beyond the coastal metropolis.
Inland Cities Bearing the Brunt
The disparity between coastal and inland air quality was stark this year. Pimpri Chinchwad, in particular, recorded an Air Quality Index (AQI) exceeding 300, placing it at the top of the list of the most polluted cities in the state. Pune also saw a dramatic deterioration, with pollution levels reaching 2.5 times higher than the figures recorded during the same period last year. This trend is further evidenced by the fact that among the ten worst-hit cities this year, only Nanded had reached the ‘poor’ category during the previous Diwali, whereas all ten cities fell into that bracket this year, indicating a systemic decline in air quality.
The Mumbai Exception: A Meteorological Shield
In contrast to the deteriorating air in the hinterlands, Mumbai managed to maintain a relatively better status, staying within the ‘moderate’ zone with an AQI of 172. While the city did see a sharp rise from 131 at 1 p.m. to 278 by 10 p.m. on Diwali—affecting regions like Bhandup West, Borivali, and Chembur—it avoided the extreme levels seen elsewhere. Professor Gufran Baig of the National Institute of Advanced Studies (NIAS) attributed this to favorable meteorological conditions, specifically an increase in sea breeze speed and a shift in wind direction over a 48-hour period, which helped disperse pollutants.
Methodology Shifts and CPCB Policy
Amidst these observations, the CPCB has introduced a significant shift in how air quality is reported. The board announced that it has capped the upper limit of readings from all continuous ambient air quality monitoring stations at 1,000 μg/m³. Consequently, any PM2.5 readings exceeding this threshold will be excluded from the National Air Quality Index (NAQI) calculation. The CPCB justifies this by stating the index is intended to reflect 'prolonged exposure' rather than 'momentary readings' caused by localized events like firecracker bursts.
Implications of Data Capping
This policy change comes under scrutiny following reports that a large portion of the capital's air-quality monitoring stations went offline during the night of Diwali. By capping the data, the CPCB aims to standardize the index based on international practices and advances in monitoring technology. However, this adjustment raises questions about how the public interprets extreme, short-term pollution spikes. The board maintains that its methodology remains under constant review to ensure the index remains a reliable tool for public health policy.
Future Trends and Environmental Governance
Looking forward, the contrast between inland and coastal pollution highlights the need for region-specific environmental strategies. While meteorological factors provided a temporary buffer for Mumbai, the consistent decline in air quality across Maharashtra’s inland cities suggests that firecracker usage and local industrial emissions are creating a cumulative burden. The CPCB’s move to refine its monitoring methodology represents an attempt to modernize data interpretation, but it must be balanced with transparent public communication to ensure that citizens are aware of the risks associated with both sustained and peak pollution levels.
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