While it was expected that pollution levels would be under control during the 2020 and 2021 lockdowns owing to the pandemic, a recent climate analysis shows that it increased year-on-year in Mumbai during March, April and May from 2019 to 2021. However, the pollution levels remained above permissible limits in cities like Lucknow and Delhi. A part of the study reveals that Kolkata was the only city to show improvement in air quality.

Researchers compared the Central Pollution Control Board (CPCB) air quality data for Delhi, Lucknow, Mumbai and Kolkata over three months from 2019-2021. The study revealed that except Mumbai, all cities showed a dip in the average PM 2.5 levels during the three months in 2020.