investigation of qualitative and quantitative of volatile organic compounds of ambient air in the mahshahr petrochemical complex in 2009

background: volatile organic compounds (vocs) are human-made chemicals widely spread in the environment and produced by petrochemical industries and petroleum refineries. the aim of this research was to evaluate the distribution of vocs in the ambient air of mahshahr petrochemical complex, iran. methods: this study was a cross-sectional research performed in 2009. we used the method numbered 1501, 1500, 2000, 1003, 1005, 1010, 2555, 1300 and 1400 of the national institute of occupational safety and health (niosh) for the sampling and analysis of compounds in the air. a total of 204 samples were analyzed using gas chromatography-mass spectrometry (gc-ms) and a gas chromatography-flame ionization detector (gc-fid). results: the mean of concentrations of the pollutants in the winter is less than in summer and a strong variation occurred among the sampling site, attributed to the change in meteorology. the results indicated high concentrations of benzene in most factories. in addition, a significant difference occurred between the concentrations of the compounds in the ambient air inside and outside the factories in both seasons ( p <0.050). conclusion: it seems that the atmospheric conditions of the workplace affect the spreading of the pollutants, causing the concentration of the pollutants in the summer to be higher than in the winter. in addition, the frequent prevailing wind speed in the region plays a major role in the distribution of the pollutants from mahshahr petrochemical factories.