Using Exposure Risk Assessment of VOCs to Evaluate Reasonable Density And Management Criteria of Gasoline Service Stations Around Urban Areas

Abstract

[[abstract]]本計畫以揮發性有機物染物的暴露風險為觀點，特別針對因加油站運作所導致揮發性有機污染物的排放情形，加以分析，希望藉由現場空氣品質的採樣分析與空氣污染物暴露量的估算，分析加油站鄰近大氣空氣品質在空間與時間上之差異，藉以建立加油站鄰近區域民眾之有害空氣污染物暴露量基本數據，以探討都會區中加油站設置距離規範之合理性，並研擬建議相關之空氣污染管制標準與減少暴露風險的策略。研究結果顯示，所測定之五種VOCs(benzene, tolulene, ethylbenzene, xylene, MTBE)，以MTBE濃度較高，其次為苯與甲苯蒸氣，乙苯與二甲苯的濃度較低，尤其是在部份加油站的周界區域，MTBE的濃度有時可高達200~300 ppb，大氣中MTBE的來源，主要來自於加油過程中所揮發的油氣。另外，針對本研究所調查的結果顯示，鄰近加油站大氣VOCs濃度在空間上的分佈，視加油站鄰近空氣污染物之擴散情形，除了加油站本身為VOCs濃度較高之處外，部份結果也顯示，有時在離加油站周界25~50公尺處，也可能會有一個尖峰濃度值，至於大氣VOCs濃度恢復為背景濃度的距離，約需要距離加油站100-200 m以外範圍，經暴露風險模擬顯示，建議約需要距離加油站100-150 m外範圍，其致癌風險才可降低至10-6水準。本研究也建議將相關之加油站管理規範，應增加距離加油站周界100公尺內，不適於住家或公共場所的設置，且加油站應設置在較空曠通風理想處，另外也建議應設定加油站之揮發性有機物「總逸散量」管制規範。[[abstract]]The major objective of this investigation is to establish the basic exposure information of hazardous VOCs for the citizens who are living nearby gasoline service stations. Several topics at least including to collect and analyze the exposure information of VOCs in the gas service stations, to monitor the chemical compositions in the stations and their surrounding area, to compare the difference in concentration of VOCs between service stations and its neighbors, to analyze the reasonable distance for gas service stations in metropolitan areas based on risk assessment, and to propose the prevention policies for reducing the exposure to VOCs. The investigation results indicate that MTBE is the VOC with higher concentration than other compounds such as benzene, toluene, ethylbenzene and xylene. The results also indicate that a distance of 100-150 m of living houses from gas stations is suggested to prevent the exposure of high-concentrated VOCs. A limit for total VOCs emission form gas stations is suggested for regulating the operation of the stations.[[note]]NSC93-EPA-Z327-00