Kolkata air quality improves with the dip in number of vehicles Updated: Updated: Share Article AAA There is a dip in the number of vehicles plying on the roads due to restriction in Kolkata. A worker seen on May 1, 2021. | Photo Credit: PTI Kolkata's air quality has significantly improved with the dip in the number of vehicles plying on the roads due to restrictions imposed two days ago to check the spread of coronavirus, an official of West Bengal Pollution Control Board said on Friday. There is far lesser emission of sulphur, nitrogen, carbon particulates in the air as number of vehicles have dwindled while commercial activities have come down significantly resulting in less air pollution, he said.