ABSTRACT
This study was conducted to assess noise pollution in one of the petrochemical complex and take practical measures to reduce it. The companyis located in site 4 of Mahshahr Special Economic Zone. In the first phase of the research, environmental noise was measured to determine the noise levels in the different sections of the plant and also identify the main sound sources.Then, using the basic acoustic knowledge, a formula has been proposed as an index of noise control priority to select one section of the plant as the first priority for controlling noise. The main sound source of the selected section was known by referring to noise maps and contours and finally its acoustic properties were analyzed. The results showed that safety; caution and danger areas of the plant under study were 16.7%, 74.5% and 8.8% respectively and a major part of the danger zone [about 54%] was related to unit Air. Noise level in 24 percent of the caution zone ranged from 80 to 85 dBA and also it was above 90 dBA in 33.4% of danger areas. Compression section which was located in unit Air was known as first priority based on Noise Control Priority Index. Dryer machines were the main sound source in this section