The rapid growth of population in urban regions is considered a point of interest concerning car ownership. Increasing car ownership leads to traffic congestion and large amounts of emissions in urban networks. The existence of toxic pollutants and particulates in the air is one of the main reasons for diseases in humans and other living beings. In this paper, the problem of traffic congestion is presented using several scales of models to explain the impact of various characteristics (road, traffic, and vehicle) on traffic flow and air pollution. Furthermore, different techniques implemented to mitigate congestion and amounts of emitted pollutants. The adopted models vary from macro-simulation, which estimates the pollutant quantity for each vehicle, to micro-simulation, which depends on several parameters affecting the vehicle and driver behavior. The overview also includes different methods of emission measurements that are performed in the field or laboratory. Air quality evaluation is presented by a numerical index (i.e., Air Quality Index) which depends on the estimated pollutant. Air Quality Index (AQI) is categorized from good to severe effect.