In this study, the author measured the frequency of symptoms and/or alterations in respiratory functions in workers of the sour gas refining industry. All workers (n = 62) were employed in the most-exposed units of the Kangan Sour Gas Refinery. The refinery is approximately 250 km east of Bushehr Port along the Persian Gulf. This cross-sectional study involved a comprehensive health questionnaire, standardized clinical examinations by physicians blinded to subjects' symptoms and concerns, and multiple spirometric values. Although gas refinery workers experienced more respiratory symptoms than the 30 controls (i.e., 37.7% vs. 23.3%, respectively), who were matched for age and smoking status, pulmonary function data were not statistically different (p > .05) between the groups. The authors concluded, therefore, that in Kangan Sour Gas Refinery workers there were no respiratory or spirometric values associated with chronic low-dose exposure to sour gas plant emissions, including hydrogen sulfide.