Aim: To study air quality of Chennai city by comparing the air quality index (AQI) with the National Ambient Air Quality Standard (NAAQS) values. Methodology In urban area, a major straddling problem is air pollution. Analyses was conducted during Jan 2016-Dec 2017 for PM2.5, SO2, NO2 and CO at different seasons in Manali, Chennai. Fine particulate sampler and Lutron CO meter were used to estimate PM2.5 and CO levels. Results: Due to different climate changes in India, higher concentration of pollution occurred during summer and monsoon season. The commercial and residential area experienced lower pollution compared with industrial areas. Case-control study showed that the result of odds ratio was significant. Interpretation: Commercial and traffic may have significant influence on air quality in Chennai.