A sudden drop in temperature on Sunday led to a significant worsening of the air quality in Kolkata, pushing readings into the unhealthy zone across major parts of the city. The cooler conditions triggered a phenomenon that trapped pollutants close to the ground, resulting in a visible haze enveloping the city in the morning.
Monitoring Stations Show Widespread Deterioration
Data from the active Continuous Ambient Air Quality Monitoring Stations (CAAQMS) revealed a concerning trend. Out of the seven stations in operation, four recorded air quality in the 'poor' category (AQI between 201 and 300). This marked a clear decline from previous days and indicated a city-wide issue.
Interestingly, the data showed a role reversal between two key locations. The Salt Lake station, which had maintained 'moderate' air for most of the past week, slipped into the 'poor' category. In contrast, the Victoria station, which had been stuck in the 'very poor' bracket for much of December, showed some improvement to 'moderate'.
Identifying the Major Pollution Sources
Officials from the West Bengal Pollution Control Board (WBPCB) pinpointed specific local causes for the pollution at different sites. The prolonged 'very poor' air at the Victoria station was largely attributed to dust emissions from construction work for a metro station on the Purple Line.
WBPCB Chairman Kalyan Rudra stated that the board had reached out to both the Army authorities and the Metro Railway authorities, requesting them to take remedial measures to improve air quality in the area.
For Salt Lake, the decline in AQI was primarily linked to extensive dust resuspension from damaged and uneven roads. Other stations, including Fort William and Jadavpur, recorded persistently high AQI readings throughout the day. Ballygunge remained on the borderline of the 'poor' category. Rabindra Sarobar was the only area that provided some relief, maintaining a 'moderate' air quality level consistently.
Winter Inversion Sets In, Experts Caution
Air quality experts have cautioned that the meteorological conditions typical of Kolkata's winters are now firmly in place. The city is experiencing winter inversion conditions, where cooler air near the ground acts like a lid, trapping pollutants due to significantly reduced vertical mixing in the atmosphere.
This natural phenomenon, combined with local emission sources like dust from construction and roads, creates a perfect storm for poor air quality. Residents, especially those with respiratory conditions, are advised to take necessary precautions as these conditions are likely to persist during the winter months.
