Nowadays, remarkable attention is being devoted to the issue of air pollutants like NO2, SO2, and CO emitted from refineries. Such contaminants have hazardous effects on people's health. They are regarded as the main contributors to lung cancer, heart disease, pulmonary lesions, etc. Hence, it is essential to provide basic solutions for reducing the effects of air pollutants or preventing their emission. For this purpose, the related studies considered risk assessment of air pollution in cities with high concentrations of pollutants. The current paper models the dispersion of NO2, SO2, and CO emitted from flares and chimneys of Phase 12 of the South Pars refinery, considering risk assessment for the citizens of Kangan, Iran. CALPUFF software was employed for simulating the conditions of the considered case study, and the outcomes were compared with those presented by Iran's air quality monitoring system. An acceptable agreement was observed between the results, while the difference could not be ignored. According to the modeling results and risk assessment, there is no risk for CO and NO2. Nevertheless, there is a risk for SO2 based on the modeling and results of Iran's air pollution monitoring system. Thus, the essence of taking preventative actions and reducing SO2 emissions is required. The novelty of this paper lies in the heart of the accuracy and authenticity of the numerical results achieved for the citizens of Kangan, Iran. Additionally, the results of the other works confirm the findings of this paper which is evidence for the validation of the findings.