Tehran University of Medical Sciences International Journal of Occupational Hygiene 2008-5109 13 1 2021 03 03 38 48 Mohsen Jamshidi Angas Department of Environment, North Tehran Branch, Islamic Azad University, Tehran, Iran Seyed Ali Jozi Department of Environment, North Tehran Branch, Islamic Azad University, Tehran, Iran Rokhshad Hejazi Department of Environment, North Tehran Branch, Islamic Azad University, Tehran, Iran Sahar Rezaian Department of Environment, Shahrood Branch, Islamic Azad University, Shahrood, Iran 2021 03 02 2021 05 22 Air dispersion modeling is an important tool to improve air quality. The main objective of this research was focused on the simulation of CO emission from stacks at the Tehran Oil Refinery Complex, Iran. The AMS/EPA Regulatory Model (AERMOD) was developed to simulate the CO dispersion from stacks between the years 2018 and 2019. The results of the model on the maximum volume of CO concentration at 1hr and 8hr for hot and cold temperature were equal to 109 μg/m3, 32 μg/m3, 360 μg/m3, 254 μg/m3, respectively. Simulated values of CO emissions were compared to those obtained area measurement campaign at 4 receptors. Maximum concentration of CO in cold period of times was more than hot period of times. This can be attributed to low air turbulence. Our analysis demonstrated that the AERMOD modeling system is applicable for air quality simulation in the near future for CO. Simulation output showed that were all centered in against mountain and  the middle of simulation area where the emission sources concentrated, and it is probably because the air pollutions were topography and source oriented. Finally, study results indicate that the simulated concentration of CO based on AERMOD, does not exceed concentration limit, set by the Iranian Ambient Air Quality Standard. It verified that CO release from oil refinery stacks don't have any significant impact on nearby communities. https://ijoh.tums.ac.ir/index.php/ijoh/article/view/499 https://ijoh.tums.ac.ir/index.php/ijoh/article/download/499/731