An analysis of the air quality index (AQI) during Durga Puja showed that Kolkata enjoyed clean air during the festival, but pollution worsened to usual levels almost immediately afterwards.
Traffic regulations were imposed in the city from October 17 to 24 this year; apart from relieving pandal hoppers and daily commuters, and helping to maintain emergency services, this move also reduced air pollution levels. The rainy weather during the festival, when lakhs of people descended on the city, also improved the air quality.
The mean daily AQI dropped steadily from 122.75 on October 18 (moderate) to 74.41 (satisfactory) on October 23 on the eve of Navami, and then dipped further to 44.39 (good) on October 24 on the eve of Maha Dashami. While PM10 levels had been slightly above the 60 ug/m3 permissible limit prescribed the Central Pollution Control Board, the PM2.5 concentration was marginally below the prescribed 40 ug/m3 limit. Both saw a drastic drop on Maha Dashami itself, on October 24.
