Very little commercialactivity during the over one-month-long lockdown and the spells of rain have improved the air quality in Kolkata, an official of the West Bengal Pollution Control Board (WBPCB) said on Wednesday.The Air Quality Index monitoring station at Ballygunje in south Kolkata recorded an AQI of 33 (PM 2.5) at 2 PM on Wednesday, which is 'good' in environmental parlance.At the same time, readings at the AQI stations of Bidhannagar, Jadavpur, Rabindra Sarobar and Victoria Memorial were 28, 29, 36 and 33 respectively.An AQI between 0 and 50 is considered 'good', 51-100 'satisfactory', 101-200 'moderately polluted', 201-300 'poor', 301-400 'very poor' and 401-500 'severe', while the AQI above 500 falls in the 'severe plus' category.The AQI hovered between 100 and 260 across different air monitoring stations before the lockdown began on March 25, the official said."This is better than the national standard of 60 (PM 2.5). It happened because of very little commercial activity during this (lockdown) period, which has pushed pollutants like sulphur dioxide, nitrogen dioxide, carbon monoxide to a very low level," the WBPCB official said.The readings at other monitoring stations of the city were also 'good' 46 in the BT Road campus of the Rabindra Bharati University and 50 at Fort William, he said.The WBPCB official said the average air quality reading across Kolkata was 20 (PM 2.5) on Tuesday due to the lockdown and rain for two consecutive days since Monday. This figure was even below the World Health Organisation (WHO) standard of 25.Last year around this time AQI hovered between 100 and 300 in different air monitoring stations in the city and neighbouring areas like Baranagar and Ghusuri.
