The goal of this study was to investigate the ambient concentrations and dispersion patterns of SO₂ originating from a gas refinery located in Asaluyeh, Iran, to determine the refinery’s contribution in emitting SO₂ in the region and also to assess SO₂-associated health risks in the study area. First, SO₂ emissions from the stacks and ambient SO₂ concentrations at 10 receptors in and around the refinery were measured from summer 2014 to spring 2015 using a Testo 350XL analyzer and a portable device (LSI-Lastem Babuc A). The amounts of SO₂ concentrations due to flaring were also calculated using the emission factors. Then ambient concentrations and dispersion patterns of SO₂ in the study area at 1-hr, 24-hr, and annual mean values were simulated on a scale of 10×10 km², using an AERMOD model. Moreover, a non-carcinogenic risk assessment was performed using a U.S. Environmental Protection Agency procedure. The results indicated that about 64% of ambient SO₂ concentrations were due to this refinery and the remaining concentrations were due to contributions from neighboring sources. The values of maximum simulated ambient SO₂ concentrations at average periods of 1-hr, 24-hr, and annual for the scale of 10×10 km² were 24,588, 1,366.1, and 498 μg/m³, respectively, which were higher than the U.S. EPA standard limits. There was also a potential health risk for short-term exposure (HQ = 1.4), but in long-term exposure an acceptable level of concentration (HQ = 0.28) was created.