| Abstract | Road side levels of CO, NO, SO,, Benzene, Toluene, Ethylbenzene, m,p-Xylene, and oXylene (BTEX) were monitored at three streets in Hanoi, Vietnam in November, 2004. Peak hourly traffic volumes were also monitored. The three streets were representative of different characteristics: Tniong Chinh street of high traffic volume (TC), Dien Bien Phil of low traffic volume (DBP), and Nguyen Trai street of high traffic volume located in an industrial zone (NT). BTEX were collected by charcoal tubes at the ground level, while other pollutants, CO, NO, and SO,, were measured by automatic instruments. The BTEX collected in the charcoal tubes were analyzed by GC - FID technique. The geometric mean concentrations of benzene, toluene, ethylbenzene, m,p-xylene and o-xylene were, respectively, 64, 62, 15, 43, and 22 pg/m3 in TC, 31, 38, 9, 26 and 25 pg/m3 in DBP street, and 123, 87, 48, 56, and 30g/m3 in NT. The 24h - average concentrations of CO, NO2 and SO2, respectively, in TC were 5.2, 0.0047 and 0.039 mg/m3, in DBP were 4.5, 0.0007 and 0.025 mg/m3, and in NT were 6, 0.0016 and 0.035 mg/m3, which are all lower than Vietnam ambient air quality standards. Measurements for BTEX in TC were also conducted at 3m, 10m, 30m and 50m downwind of the street, which showed that, toluene, ethylbenzene and xylene decreased with the distance, while benzene concentrations did not follow the same pattern. The Principal Component Analysis showed that pollutant concentrations were correlated with vehicle patterns in Hanoi and that CO and BTEX were mainly emitted from the same sources, though benzene may also come from other sources. The annual mean concentration of benzene in Tniong Chinh street was in the range of 1345pg/m3, which might cause leukemia to the people from life time exposure. |