Background and objectives: Tehran is one of the most polluted cities in the world in terms of air pollution. Modeling is a useful tool in air pollution management. The objectives of this study are to determine the distribution of the main air pollutants concentration in Tehran and to construct a photochemical model appropriate to the geography and natural characteristics of Tehran.  
Methods: In this research, by using the WRF / CAMx modeling system, the concentration of all pollutants from moving sources in a 60-day episode (22 November 2015 to 20 January 2016) is calculated in Tehran, and concentration contour has been plotted for , CO, and . In this regard, the emission inventory for moving sources has been calculated with coding in the FORTRAN and the outputs of the WRF meteorological model was prepared for air quality modeling and then, by using the CAMx model, the air quality of Tehran was simulated during this 60 day period.
Results: The results of the meteorological simulation have been compared and validated with the measured values at the Mehrabad station. Also, for the purpose of validation, the results of the simulation of pollutant concentrations of the particle matters with the measured concentrations of air pollution monitoring stations have been compared. In this study, the concentration contour and the distribution of pollutants have been drown for , CO, and . According to the concentration contours, the center of Tehran is more polluted. The Normalized Mean Bias for Sharif, Shadabad, Shahrery, and Golbarg stations is 41%, 24%, 37.8% and 37.2%, respectively. Which are acceptable in the simulation of air pollution.
Conclusion: This study shows that the amount of air pollutions is higher in the areas where moving sources are more in traffic, and it can be said that the majority of Tehran's air pollution is generated by moving sources.