Comparison of Air Pollutants and Air Quality Index using Spatio-Temporal Variation in Chennai City, Tamil Nadu

In recent years, air pollution in Chennai city in India causes some health effects. This study examines the spatial-temporal characteristics of ambient air quality in five stations Adyar, Anna Nagar, Kilpauk, Nungambakkam and Thiyagaraya Nagar from 2017 to 2022. The surface level aerosol pollutants like particulate matters (PM2.5& PM10) and gaseous pollutants Sulfur dioxide (SO2) & Nitrogen dioxide (NO2) were obtained from Tamilnadu Pollution Control Board (TPCB) for five years which includes pre-COVID, during and Post- COVID - period. The results showed that fine particulate matter (PM2.5) and coarse particulate matter (PM10), decreased by 19.49% and 31.91% respectively and gaseous pollutant SO2 and NO2 slightly increased by 7.84% and 1.2 % respectively during 2021 as compared with 2017.The particulate matter (PM2.5& PM10) level exceeded the National Ambient Air Quality Standards (NAAQS) as well as the WHO recommended Air Quality Guidelines during 2017-2019(Pre-COVID) and low during 2020-2021(During COVID and Post-COVID). The average Air Quality Index (AQI), calculated from the date decreased from 120(2018-2019) to 93(2020-2021) in Chennai city. The AQI and PM2.5/PM10showed the highest pollution level in winter and lower in summer. PM10 was the primary pollutant, followed by NO2, PM2.5& SO2with spatial and temporal variations. The proportion of pollutants PM2.5and PM10decreased but increased for SO2 and NO2. This study offers useful data and resources for further research on Chennai's air quality.