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Integrating On-line And Off-line Measurement For Assessment Of Potential Human Exposure To Particle-bound Polycyclic Aromatic Hydrocarbons (pPAHs) In Bangkok, Thailand


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T. Chetwittayachan, D. Shimazaki & K. Yamamoto


Integrating on-line and off-line measurement for assessment of potential human exposure to particle-bound polycyclic aromatic hydrocarbons (pPAHs) in Bangkok, Thailand T. Chetwittayachan1, D. Shimazaki2, K. Yamamoto3 1 Department of General Science, Chulalongkorn University, Thailand. 2 Engineering Research Institute, The University of Tokyo, Japan. 3Environmqtal Science Center, The University of Tokyo, Japan. Abstract A photoelectric aerosol sensor (PAS), which provides continuous signal in relation to the total particle-bound polycyclic aromatic hydrocarbons (pPAHs) concentration, was used to measure the real-time concentrations in the vicinity of road in Bangkok (Thailand). The measurements at roadside and general areas were carried out for approximately seven consecutive days in March and in August 2001. Potency equivalency factors (PEFs) of classified carcinogenic PAHs, which have been developed by the California EPA, was applied to assess the lifetime cancer risk of potential human exposure to these substances from the real-time measurement. A satisfactory linear correlation was obtained between the total amount of pPAHs detected by the PAS and the total PEF-weight concentration of seven carcinogenic PAHs determined by gas chromatography/mass spectrometry (GCMS). At roadside, no large difference in average pPAHs concentration were observed between both periods studie4 whereas larger difference was found at the general are giving the ratio of the average concentration of the former to that of the latter a value of 2:l. This suggests that pPAHs more dispersed during the second campaign, due to stronger wind flow observed. As a result, the background cancer risk estimated at the general area of the second period was about 1.5 times higher than that of the first period. At roadside areas, including at ground and 4- storey height levels, an additional cancer risk due to road traffic was 1.2 x 10-6 and 7.1 x 10-7, respectively. In addition, the additional risk of the motorized road user during workday was estimated as 1.8 x 10-6. This approach could then give a simpler way to assess the potential risk associated with human exposure to pPAHs.