Assessment of health risks of exposure to hazardous chemicals by semi-quantitative method in a gas refinery complex

Background: Gas refining is a process in which workers are exposed to different chemicals. This study aimed to assess the health risks caused by exposure to these substances in order to determine hazardous jobs and to present controlling methods. Materials and Methods: This cross-sectional study was performed on the workers at gas refinery in 2015. The sample included all the staff in operational parts and the selection was by census. To determine the risk of exposure to chemical pollutants, the method proposed by the Department of Occupational Safety and Health of Malaysia was used. Following this procedure, first the materials and processes were identified. Afterwards, risk and exposure rates were calculated. Using these two rates and risk rate formulas for individual chemicals, the exposure was calculated. Results: The results showed that employees were exposed to 103 different types of chemicals that collectively were causing 162 types of exposure in different jobs. Of the total exposures, 5 percent were evaluated as “inconsiderable risk rate”, 51 percent as low, 30 percent average, 13 percent high, and 1.2 percent as “very high risk rate”. Conclusions: The highest risk rate of exposure to chemicals in the refinery was related to benzene in stabilizer and topping area shift works (RR = 5) as well as the shift works in feller area and evaporation pools with risk rate of 5, ranking their risk as very high, indicating that corrective actions should start on this hazardous and carcinogenic chemical as soon as possible.