Atmospheric concentrations of particle-bound polycyclic aromatic hydrocarbons (PAHs) were measured at two roadside sites in Bangkok, where severe health problems have been caused by traffic air pollution, in order to investigate their atmospheric behavior and to assess the health risk. Comparing the different road configurations of the two sites with or without an elevated highway above, it was suggested that under the elevated highway air becomes stagnant, which leads to higher PAH concentration levels. The diurnal variation of PAH compositions were also examined in relation to the traffic flow and its profiles. Most of ambient PAHs existed adsorbed to submicron particles, which are fine enough to be inhaled to human respiratory organs easily. The lung cancer risk was estimated at 6.4E-05 and 4.3E-05 at respective site, and those risk levels are not negligible.
PAHs, PM, Particle size, Health risk, Roadside atmospheric environment, Bangkok