|摘要: ||本研究旨在探討都會區及營建工地不同型態街塵中微粒之含量、特性、負荷及洗街作業對街道揚塵可產生之減量效益。針對南部某都會區六種不同市區型態地區道路(郊區、工業區、工商區、商業區、住商區及住宅區)與四個營建工地周邊道路進行街塵採樣分析與研究，探討不同區域之道路及營建工地周邊道路街塵特性及細微粒徑，以了解因交通工具夾帶、磨損、輾壓及其捲揚致街塵飛散或沉降後之分布特性，以及工地周圍大型車輛所帶入及帶出的塵土對道路的影響，進而分析不同砂土粒徑，並推估都會區受空氣污染衝擊，及細微粒徑之粒狀物對人體健康所造成影響。由於營建工地涵蓋範圍甚廣，施工期間所產生之揚塵嚴重影響附近空氣品質，對附近居民感受最於直接，藉此探討營建工地周邊道路之街塵負荷及洗街效率，觀察營建工地管理人員是否有落實周邊道路之洗掃作業。研究結果顯示，都會區不同背景區域之洗街前塵土負荷平均為0.83 g/m2，洗街後塵土平均負荷為0.34 g/m2，平均塵土洗街效率為56%，道路髒污等級皆有所提升，但洗街作業二天後鋪面道路因交通工具排放及掉落亦或者人群之活動期道路街塵負荷皆有回覆至洗街前塵土負荷之趨勢，郊區及工商區之道路髒污等級由洗街後的A級再回覆降為B級道路。而營建工地周邊道路洗街前塵土負荷平均值為10.6 g/m2，洗街後塵土負荷平均值為1.46 g/m2，塵土洗街效率平均值為83.4%，洗街後各路段之塵土負荷皆有效減少，道路等級皆有所提升，整體而言營建工地周邊道路與都會周邊道路相較，洗街前之平均總街塵，塵土及坋土負荷分別為6.06、12.8及33.4倍，洗街後之平均總街塵，塵土及坋土負荷分別為2.43、4.29及10.8倍，若能有效控管都會區與營建工地之洗掃作業，對周邊區域之空氣品質皆會提升許多。 同時，經由MOUDI細微粒徑之分析，可顯示出經由洗街作業的進行，無論是都市區域道路亦或者營建工地周邊道路，小於3.2μm之細微顆粒皆有些微降低之趨勢，並留下較大之顆粒(大於18μm以上之顆粒)，由於都市區域周邊道路的影響因素較多，所以洗街前後之細微粒徑下降之百分比相較營建工地並不明顯，同時洗街後街塵之回覆情形，經由二天內之交通工具之輾壓、大氣中微粒之沉降現象，原道路中更細微顆粒增加之趨勢，亦值得關注。|
This study investigated dust emissions from construction sites in urban areas in terms of their contents, characteristics, and loads of particulates. The benefits of street sweeping on dust reduction were considered. Six local roads in six types of zoned land (suburban, industrial, industrial–commercial, commercial, residential–commercial, and residential zones) and four roads surrounding construction sites in an urban area in southern Taiwan were sampled in this study. The street dust on these 10 roads was sampled and analyzed to examine the variations in characteristics and particle sizes.Subsequently, this study explored the characteristics of street dust distribution caused by transportation equipment (e.g., carrying, wearing, mangling, and winding) and the effects of dust carried in and out by large vehicles on the roads surrounding construction sites. Furthermore, through an analysis of silt particle sizes, we surmised the environmental impacts of urban air pollution and the health hazards of particulates.Because a construction site covers a massive area, dust emissions during construction severely affect the air quality and the quality of life of residents in surrounding areas. This study examined the street dust loads and street sweeping efficiency levels on roads surrounding construction sites by observing street sweeping as implemented by construction managers. The results revealed that the average presweep and postsweep dust loads in variously zoned land areas were 0.83 and 0.34 g/m2, respectively, showing an average street sweeping efficiency of 56% and an improvement in dirtiness rating. However, because of dust emissions from transportation equipment or human activities, the dust loads on the paved roads reverted to the presweep levels after two days. The street dirtiness ratings in suburban and commercial–industrial zones reverted from level A to level B. The average presweep and postsweep dust loads on roads surrounding construction sites were 10.6 and 1.46 g/m2, respectively, demonstrating an average street sweeping efficiency of 83.4%. Both the street dust loads and street dirtiness ratings were improved in all four sampled areas. In summary, the average presweep street dust, dust soil, and silt loads on the roads surrounding construction sites were 6.06, 12.8, and 33.4 times their respective baselines; whereas the average postsweep street dust, dust soil, and silt loads were 2.43, 4.29, and 10.8 times their respective baselines. Therefore, effectively monitoring the implementation of street sweeping in urban construction areas may significantly improve air quality in surrounding areas.Through a microorifice uniform deposit impactor, the particle size analysis revealed that the postsweep distributions of particulates smaller than 3.2 μm on both urban or construction roads were slightly reduced, and only particulates larger than 18 μm remained. Because more factors affected the street dust loads of urban roads than construction roads, the percentage drop of particle size on urban roads from presweep to postsweep was not as significant as that on construction roads. In addition, the trend of increased particulates of relatively small sizes after two days of vehicular mangling and sedimentation was noteworthy.