In the socio-economic development of Ba ria-Vung tau province, industrial development plays an important role, including the heavy industry of producing steel and steel billets from scrap. Currently, in the province, there are 6 steel factories that produce steel from scrap and operate in Phu My town. During the production process, although factories installed exhaust gas treatment facilities, the treatment has not been effective, leading to air pollution from steel factories becoming one of the issues that have received local attention recently. The study calculated air pollution emissions and used the TAPMAERMOD model system to simulate the dispersion of air pollution from a steel factory to surrounding areas, of which one factory was selected for a case study (in Phu My town). Simulation results showed that the highest 1-hour, 24-hour, or 8-hour average concentrations of SO₂, NO₂, CO, PM₁₀, and PM_2.5 all reached QCVN 05:2023/BTNMT in both seasons (dry and rainy). Meanwhile, the highest 1-hour average concentration of TSP exceeds 2.3 times (in the dry season) and 2.0 times (in the rainy season) in QCVN 05:2023/BTNMT. The study also simulated in the case of problem with exhaust gas treatment systems. In addition, the study calculated the environmental safety distance for the surrounding area and proposed measures to reduce air pollution from steel factories.