ABSTRACT
The lockdown was implemented by the government of India during the pandemic period due to Covid-19. This paper presents the effect of lockdown on the air quality index and various pollutants in five major locations in the Chennai city of Tamil Nadu. The air pollutants such as PM10, PM2.5, SO2 and NO2 from the monitoring stations were analyzed from 2018 to 2019 (pre-Covid period) and from 2020 to 2021 (during-Covid period). The results demonstrated that the concentration of PM10 and PM2.5 reduced about 48% and 39% respectively. Similarly, significant reduction in the pollutants SO2 (-25%) and NO2 (-10%) has been observed. In the same way, AQI level before and during lockdown in Chennai city was observed satisfactory to moderate categories. The maximum reduction in AQI was observed in Adyar (-50.38%), followed by Nungambakkam (-44.18%), TNagar (-40.31%), Anna Nagar (-39.98%) and Kilpauk (-30.74%). Overall study implies that regulatory measures in a certain location in a suitable time period control the pollution and protects the environment.