高速公路收費站揮發性有機物濃度特徵之研究

Characteristics and Contents of Volatile Organic Compounds in the Atmosphere of a Toll-way Station

本研究探討高速公路收費站收費亭揮發性有機物（Volatile Organic Compounds，VOCs）濃度與車流率之相關性。研究發現小型車回數票、小型車找零和大客車／貨車等三種車道收費亭苯（＝1.91～ 6.81ppb） 、甲苯（＝7.35～24.42ppb）、乙苯（＝0.98～4.04ppb）、二甲苯（＝2.38～10.52ppb）、甲基第三丁基醚（＝1.57～6.24ppb）及五種主要 VOC 之總和（＝14.29～52.17ppb）濃度均小於石油煉製廠、汽車修理廠及加油站，但約略與小汽車與公共汽車內濃度相仿。就各類型車道收費亭之五種主要 VOC 之總和濃度（Y：ppb）與車流率（X：103 輛／班次）進行線性迴歸分析，可發現小型車回數票、小型車找零和大客車／貨車車道收費亭迴歸分析結果分別為：Y=7.92X+1.59，R2 ＝0.50，n＝32； Y=11.28X+3.92，R2 ＝0.74，n＝27；Y=9.50X+2.94，R2 ＝0.48，n＝22。由以上結果可知車流率可有效解釋各類車道收費亭各 VOCs 濃度。由於收費亭之 VOCs 濃度除受車流率影響外，亦可能同時受到現場風速及溫度之影響，因此本研究結果對是否應用在其他季節仍有進一步研究之必要。

The objective of this study was set out to assess the correlations between the concentrations of volatile organic compounds (VOCs) in the atmosphere of a toll-way station lane booth and its vehicle flow rates. Results show the concentrations of the five target VOCs (benzene=1.91～6.81ppb, toluene=7.35～ 24.42ppb, ethylbenzene=0.98～4.04ppb, xylene=2.38～10.52ppb, MTBE=1.57～6.24ppb) and the sum of the above five VOCs (= 14.29～52.17ppb) found for the three types of lane booths (car/ticket-collecting, car/cash-collecting, and bus/truck) were lower than those found for the petroleum refinery, car repairing, and gas station workplaces, but was comparable with those for the bus stations. By using linear regression analysis, results show that the sum of the above five VOCs concentrations (Y: ppb) can be effectively explained by vehicle flow rates (X: 103 vehicles/shift) for the three types of lane booth. This study yielded the regression equations of Y=7.92X+1.59,R2 ＝0.50,n＝32；Y=11.28X+3.92,R2 ＝0.74,n＝27； Y=9.50X+2.94,R2 ＝0.48,n＝22 for the car/ticket-collecting, car/cash-collecting, and bus/truck lane booth, respectively. Yet, it is true that the concentration of VOCs for a lane booth could be also affected by its on-site wind speeds and temperatures. Based on this, whether the results obtained from this study are applicable to other seasons required further investigations.