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

Department of Civil Engineering, Sri Sivasubramaniya Nadar College of Engineering, Chennai - 603110, India

Abstract

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 (PM_2.5 & 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 (PM_2.5) 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 (PM_2.5 & 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 PM_2.5/PM₁₀ showed the highest pollution level in winter and lower in summer. PM10 was the primary pollutant, followed by NO₂, PM_2.5 & SO₂ with spatial and temporal variations. The proportion of pollutants PM_2.5 and PM₁₀ decreased but increased for SO2 and NO2. This study offers useful data and resources for further research on Chennai's air quality.