空間性移污分佈與風險分析

Abstract

移動污染(以下簡稱移污)是都巿的主要空氣污染且會危害居民健康，有必要評估其對各區域所造成的影響，然而由於車流、車行里程及人口的不同，導致其對各區域所造成的風險亦因而不同，唯移污的空間分佈並不易計算，過去雖曾有道路密度(RND)法，但RND並不一定能反應車流量大小，易低估高污染區而造成誤差。因此本研究擬發展適當的方法評估移污所造成的空間性影響及風險。 本研究擬探討以車流資料來改善RND法，唯行駛距離不同亦會造成排放量不同，故亦擬以車行里程進一步改善之。本研究擬探討建立一些方法，用以分析移污在都巿中的空間分佈，總污染排放量採用RND法的計算方式，依耗油量估算，空間分佈分析則是將案例區劃分成多個網格，再分別依RND及所建立的方法分配總污染量至各網格，並分析及比較各方法所得的移污空間分佈的合理性。此外，亦配合人口分佈及各方法所得結果比較及分析移污空間性暴露風險。由於街道形式亦會明顯影響移污之分佈，本研究因而擬以OSPM街谷模式模擬街道之移污濃度，同時配合街道旁的人口以探討街道移污對周遭住戶的暴露風險。所建立的方法將應用於台北市，依案例研討結果分析所建立方法的實用性與優劣點。預期所發展的方法可改善移污空間分佈的推估品質，以利於進行相關的決策分析

Vehicle exhaust emission is the main source of air pollution in metropolitan areas in Taiwan and greatly affects citizens and causes health risks. Different traffic flows, spatial mobile pollution distributions, and population distributions can cause different levels of impact and health risk. This study is thus initiated to develop appropriate methods for assessing the spatial impact and risk caused by the mobile pollution. Taipei City is the case study area for this research, and the proposed methods will be applied to evaluate its mobile pollution spatial impact and risk. It is not easy to evaluate the spatial distribution of the mobile pollution. Although a method called the Road Network Density (RND) method had been previously proposed, similar RNDs do not imply similar traffic flows and thus may subsequently underestimate the pollution in high traffic-flow areas, and the error may be quite significant. Therefore, the traffic flow is also analyzed for developing a method to resolve this problem. Furthermore, different traveling distances can cause different emissions, and thus the vehicle miles traveled are to be estimated for establishing another enhanced method. Before implementing these methods, the total mobile pollution (TMP) emission from the entire city is estimated according to the amount of gasoline consumed, based on the approach proposed by the RND method. The entire study areas are divided into numerous grids in the same size. The TMP emission is allocated to each grid according to its ratio determined by the RND and proposed methods. With the pollution distributions determined by the methods and the population distribution of the city, spatial impacts and health risks caused by mobile pollution are estimated. In addition, since similar emission in different types of roads can generate different distributions of mobile pollution, the Operational Street Pollution Model is adopted to simulate air pollutant concentrations on road sides, and the results obtained are to be used to assess the exposure risk on the residents living in the road sides. It is believed that the proposed methods can improve the estimation and assessment of spatial mobile pollution distribution and subsequently facilitate related decision-making analyses.