Dust deposited on the leaves of trees can be effectively used as the monitors of polycyclic aromatic hydrocarbons (PAHs). The dust deposited on the leaves can be used as an appropriate index for evaluating PAHs in the atmosphere. This research was conducted to determine the origin and health risk assessment of PAHs accumulated on the leaves of trees in the city of Ahvaz. For this purpose, samples were taken at leaves on 10 points with different land uses including industrial, recreational,

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... traffic and residential ones. After preparation, to determine the type and concentration of PAHs, the compounds were analyzed by GC-MS. The results showed that 15 types of PAHs had been identified from 16 important compounds identified by EPA in the dust samples. The concentration of compounds was the range of 3.3-110 microgram per kilogram. The maximum and minimum of PAHs carcinogenic in particles trapped on leaves were in the Kut-Abdolah with 530 ppb and Shahrvand Park Station with 5.13 ppb, respectively. Also, the average relative of LMW/HMW in the aromatics contained in the deposition of particles on trees was 0.5; further the analysis of the main components of aromatic hydrocarbons (PAHs) showed that there was no specific source for these compounds in Ahvaz, and these compounds could be from fossil fuels, urban traffic, natural gas, generally showing a pyrogenic origin.