Airborne polycyclic aromatic hydrocarbons (PAH) in Bangkok urban air I. Characterization and quantification

The behavior of airborne PAH is related to their physical and chemical prop erties. Thus, in a tropical urban environment, they are expected to have ph ase distributions and reactivities which are quite different from those est ablished for temperate areas, Nevertheless, such studies are still scarce i n the tropics. In this study, the characteristics of PAH in Bangkok urban air were investi gated with respect to gas-particle partitioning and dependency on particle size. A sampling system which consisted of an 8 stage size fractionating ca scade impactor (Andersen "low volume" Sampler) and a downstream XAD-2 adsor bent tube was used for sample collection. Nine PAH, classified as carcinoge nic and co-carcinogenic compounds - Pyrene (PYR), Benz(a)Anthracene (BaA), Benzo(e)Pyrene (BeP), Dibenz(a,c)Anthracene (DBacA), Benzo(k)Fluoranthene ( BkF), Benzo(a)Pyrene (BaP), Dibenz(a,h)Anthracene (DBahA), Benzo(ghi)Peryle ne (BghiP) and Trimethylcholanthrene (3MC) - were quantified by ultrasonic extraction and HPLC with fluorescence detection. The quantitative and quali tative compositions of these nine PAH samples are described. It was conclud ed that the sampling system designed in this study is suitable for the inve stigation of airborne PAH (with molecular weights of 202 and above) in the tropical climate since even at sampling temperatures of similar to 35 degre es C, none of the listed PAH was traceable in the second layer of the XAD-2 adsorbent tube.