Air Quality 'moderate', but nearly 'poor' in some city pockets

The overall air quality in the city and its surrounding areas hovered in the "moderate" category on Monday, the day after Kali Puja and Diwali, but degraded to nearly "poor" in areas under two air monitoring stations.

The Air Quality Index (AQI) reached 196 (PM 2.5), a little less than 201 (poor) at Fort William automated air monitoring station at 7 pm, a West Bengal Pollution Control Board official said.

He said the AQI was 139 at the same monitoring station at 11 pm on Sunday, the day of Kali Puja and Diwali.

An AQI between 0-50 is considered "good", 51-100 "satisfactory", 101-200 "moderate", 201-300 "poor", 301-400 "very poor", and 401-500 "severe". Above 500 it is in "severe-plus emergency" category.

PM 2.5 is particulate matter 2.5 microns and below. Those are small particles floating in the air.

He said the AQI was 186 at the automated air monitoring station at Rabindra Bharati University compound, B T Road at 7 pm on Monday. The figure was 173 there at 11 PM on Sunday.

The AQI was also high in the moderate category on Monday registering 177 at Rabindra Sarobar and 175 at Victoria monitoring stations, the official said.

The AQI at Bidhannagar was 155 at 7 pm, higher from yesterday's 111, the official said.

Air Quality Index in two monitoring stations located in residential areas in south Kolkata was, however, lower a compared to others - 124 AQI at Ballygunge and 128 at Jadavpur at 7 PM, the official said.

Asked if the degradation of AQI at some stations on the day after Diwali could mean that the WBPCB and the police had relaxed vigil their as the festival is over, the official said, "It is in Moderate category. We haven't slackened our vigil. The rise in AQI can be attributed to various factors including weather conditions."