Study on Roadside Air Pollution Caused by BTEX Compounds in Beijing

The concentrations of BTEX (Benzene, Toluene, m,p -xylenes and o-xylene) were monitored at roadsides of three kinds of urban road (open road, cross road and street canyon) in Beijing during 2008-2009. Each sampling was taken with the change of traffic volume at 7:30, 11:30, 14:30 and 17:30. Air samples were pre-concentrated on Tenax-TA tubes, which were analyzed by a GC system coupled with FID in laboratory after thermal desorption. This study presents the contamination status, temporal and spatial variations of BTEX in ambient air. During the monitoring period, diurnal average mass concentration of BTEX was 8.8-80.0 μg/m3, and exhibited two peaks. The highest mass concentration of BTEX reached 229.69 μg/m
³
in summer while the lowest appeared in autumn. The air of street canyon had the highest concentration compared to the other two kinds of road. We also chose Guangzhou as the control city, which had a higher concentration of BTEX.