Air pollutants from iron and steel making operations have historically been an environmental concern. The factory located at Ahwaz, Iran, has two production lines namely, 630 and 650, which produce iron parallel edge. The objective of the study is to determine indoor respiratory particulate matter (RPM) and FeO concentrations and their comparison with NIOSH standards. This is a crossâ€“sectional study of personnel working in different environmental conditions. There were significant differences in mean concentrations of RPM (P< 0.05) in line 650 but not in line 630 as compared to NOISH standard (3 mg/m3). The FeO concentrations in line 630 and 650 are significantly lower than the NIOSH standard (5 mg/m3). There is maximum FeO concentration in station 7 (0.8 mg/m3), due to remains of iron on the billets. In other words, after cutting the beam by saws, carried out with water pressure of 150 Bar and immersing in cooling beds, the temperature decreases from 550 Â°C to 150 Â°C. As the result, airborne iron oxide concentrations decrease in the respiratory air zone of workers. There is maximum RPM concentration in station of Billet rejecter for line 630 (7.645 mg/m3), because this station carries out peel action on metal. The primary form of RPM is not directly related to the iron handling but may be related to improper ventilation and exhaust system.