Objectives: Investigating and determining the share of urban sources of air pollutants is an essential step in pollution control management. Studies indicate the main source of air pollution in Tehran is the indiscriminate use of energy, while vehicles produce more than 85% of air pollution. Thus vehicles have the most important role in Tehran’s air pollution.

Methods:  The present study investigated the share of different types of vehicles in Tehran according to fuel consumption and emission factors and based on output data from the EMME/2 software of Tehran Comprehensive Transportation and Traffic Studies in a morning peak hour in 2013.

Results: The emissions of criteria pollutants (CO, HC, NO_X, SO_X, and P.M.) vary in different types of gasoline and diesel vehicles according to emission factors, type and number of vehicles, fuel consumption, and car mileage. Generally, in a traffic peak hour in a morning in 2013, the share of a variety of sedans, taxis, motorcycles, pickups, minibuses, public buses, trucks, and school buses in pollutants emission was 48.36, 18.87, 16.02, 10.35, 1.50, 2.49, 1.28, 1.13 percent, respectively.