AQI slips to ‘very poor’ category after season’s 1st notable temp dip in Kolkata
Times of India | 6 December 2025
Kolkata: The air quality in Kolkata deteriorated on Monday as the season's first notable dip in temperature coincided with a surge in pollution levels across the city.
Real-time monitoring data from multiple stations showed the Air Quality Index (AQI) slipping into ‘poor' and ‘very poor' categories in most neighbourhoods, raising fresh concerns about winter-time respiratory risks.
The worst pollution spike occurred during the early hours of the day when the combination of low temperatures, calm winds, and high moisture levels trapped pollutants close to the ground. PCB scientists said this was an early sign of the winter inversion phenomenon — a meteorological condition in which a warmer air layer prevents cooler air below from rising, effectively sealing in smog and particulate matter. "This inversion acts like a lid over the city. Whatever emissions we generate — from vehicles, roadside dust, construction, or industry — remain suspended near breathing level," said atmospheric scientist, Abhijit Chatterjee, of Bose Institute. Data recorded at 7 am revealed the scale of the pollution surge. Victoria Memorial topped the charts with an AQI of 329, firmly in the ‘very poor' range. Fort William, Jadavpur, and Ballygunge followed with readings of 283, 282, and 233, respectively — all in the poor category. Even traditionally greener pockets such as Rabindra Sarobar and RBU (BT Road) showed AQI levels above 140, falling in the moderate category but still unsafe for prolonged exposure. Although air quality showed marginal improvement by late afternoon, readings remained high throughout the day, with major locations continuing to report pollution levels above permissible limits. Health experts issued a strong advisory, asking residents to limit outdoor physical exertion during morning hours.
"People should avoid brisk walking, jogging, or open-air workouts in the early hours," said a city pulmonologist, Dr Arup Halder.
"Children, senior citizens, and those with respiratory or cardiac conditions are particularly vulnerable. Indoor exercise is advisable," he advised. Doctors also recommended wearing N95 masks while stepping outdoors, keeping windows shut during peak pollution hours, and using air purifiers. The elderly and people with asthma were urged to monitor symptoms over the next few days.
Urban planners warn that the seasonal worsening of air quality may persist through Dec and Jan unless emission sources are controlled. .