The growing Urbanization, Industrialization, Institutional, and IT sector development contribute to the exponential growth of motorized road transportation increasing the composition of harmful gaseous pollutants in ambient air. So, it is necessary to analyze and quantify the concentration of pollutants such as CO, NOx, SOx, and PM10 (for calculating the Air Quality Index) in ambient air at traffic signal zones in National Highway 948 across Coimbatore city and to model its dispersion using Quantum GIS. Using a Respirable Dust Sampler, the ambient air samples are collected at various locations based on heavy traffic signals zones during the month of December 2022 – March 2023.Quantified data are compared with National Ambient Air Quality Standards (NAAQS) to know about air quality, i.e., Air Quality Index. The dispersion rate in terms of concentration of CO, NOx, and SOx in the sampling locations of National Highway 948 revealed that; In comparison to other sampling months, the mean NOx concentration was higher in December at SL1 (78 µg/m³).The mean concentration value of SOx was high at SL2 (57 µg/m³) in the month of February 2023, and the mean concentration of CO is relatively high at SL1 (1.93 mg/m3) in NH 948.Sampling Locations such as SL1, SL5, SL7, and SL11 fall under the category of Poor compared to other sampling locations because of improper alignment of roadway, Traffic congestion, Liberty, and Violation of Traffic rules, Lack of vehicular maintenance, and End life vehicles. The lack of implementation of environmental regulations contributes to the bad air quality in most Indian cities.