Volatile organic compounds are one of the most important air pollutants in cities that are caused by cars, chemical and petrochemical industries. A very important component of volatile organic compounds is PAHs, which have an aromatic structure and are formed by many natural processes and human activities. These compounds are widely used in petroleum and petrochemical products and industries, as solvents in paint and adhesive industries and have important health effects on humans, such as cancer. The aim of this study was to investigate the amount of Poly Cyclic Aromatic Hydrocarbons (PAHs) in indoor and outdoor air during the hot and cold seasons.
Materials and methods: Sampling of this study was performed by selecting 12 stations from Tehran in a one-year period using absorbent tubes and individual sampling pump with a flow rate of 200ml / min at a distance of 1-2.5 meters from the ground. From each station, three samples were taken in dry period and three samples in wet period (72 sample). The collected samples were stored in the refrigerator and then transferred to the laboratory and after extraction from the adsorbent surface were read by Gas Chromatographic.
Results: The results showed that during the sampling period in dry in ambient air, the average concentration of PAHs was equal to 20.2 ppb and in wet outdoor environment( ambient air), the average concentration of PAHs was equal to 23.6 ppb. Also, in the sampling period in dry (indoor air), the average concentration of PAHs was equal to 20.6 ppb and in wet (indoor air), the average concentration of PAHs was equal to 23.8 ppb.
Conclusion: In general, the average concentration of PAHs in the cold season(wet) is more than the hot season (dry), which is due to pollution of domestic and commercial canters with the creation of inversion in Tehran in the cold season and increased photochemical reactions in the hot season and become faster This material is to other materials. The amount of these compounds in high-traffic areas and the city centre is more than other places, and by moving away from these high-traffic points, the concentration of these compounds is gradually reduced.