大臺北地區氮氧化物空間分佈特性之探討

Spatial and Indoor/Outdoor Distributions of Nitrogen Oxides Concentrations in Taipei

翁瑞昭(Jui-Chao Weng)

指導教授 ： 詹長權

國立臺灣大學/公共衛生學院/職業醫學與工業衛生研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.00590

摘要

背景－研究指出室內氮氧化物同時受到室內與室外污染源的影響，但大部分的研究多以探討家戶室內外濃度的關係為主，其他室內微環境的研究則相對較少。因此本研究將針對氮氧化物在室外水平及垂直的三維空間分佈狀況，以及家戶、辦公室與運動中心的室內外氮氧化物濃度比例進行研究，並探討潛在影響因子與氮氧化物濃度之間的關係。

方法－本研究以大臺北地區的人口密度為基礎，建立高空間解析度之細部監測網絡，包括21個都市背景監測點與19個交通監測點，並從中選出11個監測點作氮氧化物在垂直剖面的濃度分佈探討。此外，同時也從40個室外監測點中選出19個家戶、23間辦公室以及7家運動中心進行室內外氮氧化物濃度的監測。研究時間為2009年6月至10月，所有樣本均以Ogawa被動式採樣器進行為期14天之採樣，並以直讀式儀器在潛在污染附近連續量測二氧化氮的濃度，另一方面也針對各個監測點完成室外環境調查表與室內污染源及通風狀況之問卷。

結果－本研究在19個交通監測點所量測的NOx濃度顯著高於21個都市背景監測點，但NO2濃度僅達邊際顯著差異。NOx之平均濃度在交通監測點與都市背景監測點分別為39.7 ppb與26.4 ppb，而NO2的平均濃度則分別為21.2 ppb與18.4 ppb。垂直分佈方面，結果顯示氮氧化物濃度隨著垂直高度的增加而下降，四至六樓（11.1-17.5公尺）的NOx與NO2濃度分別是一至三樓（1.5-7.9公尺）的0.79倍與0.75倍；而七至八樓（20.7-23.9公尺）的NOx與NO2濃度則分別是一至三樓（1.5-7.9公尺）的0.64倍與0.67倍。室內外濃度分佈方面，總共完成了19個廚房、14個臥室、9個客廳、23個辦公室、7個健身房、7個綜合球場、7個溫水游泳池及各場所室外之採樣，其中廚房的NOx與NO2濃度分別是38.0 ppb與22.8 ppb，而溫水游泳池的NOx與NO2濃度分別是48.0 ppb與24.0 ppb，均顯著高於室外濃度。相較之下，辦公室室內的NOx與NO2濃度分別是18.7 ppb與12.0 ppb，顯著低於室外濃度。Indoor/outdoor ratio方面，NOx在廚房與溫水游泳池的平均indoor/outdoor ratio分別為1.47與2.03，而NO2的平均indoor/outdoor ratio分別為1.28與1.54。此外，本研究同時也發現在臥室開窗會顯著提高室內的NO2濃度，而在廚房使用液態瓦斯燃料進行烹調時，NOx濃度與使用非液態瓦斯之廚房達邊際顯著差異。另一方面，NO2濃度在溫水游泳池附近的鍋爐機房之中以熱水鍋爐周圍最高，呈一明顯的濃度梯度，表示鍋爐為一室內污染源。

結論－室內與室外的氮氧化物污染源，諸如在廚房使用瓦斯爐、在運動中心使用熱水鍋爐以及交通源的排放，均會使室內微環境的氮氧化物濃度上升。

關鍵字

氮氧化物 ； 二氧化氮 ； 室內空氣品質 ； 交通排放 ； 空間分佈

並列摘要

Background－Previous studies have demonstrated indoor air quality of nitrogen oxides (NOx) is related to both outdoor and indoor emission sources but most of them focused mainly on homes in Taiwan. There are relatively few studies on indoor NOx issues in other indoor microenvironments. The purpose of this study is to characterize spatial and indoor/outdoor distribution of NOx in homes, offices and sports centers in Taipei and investigate factors affecting their distributions.

Methods－We used a population density based sampling strategy to select 40 sites in Taipei, including 21 urban background sites and 19 traffic sites for our field sampling. Among them, 11 sites were selected to study vertical profiles of NOx in Taipei. In addition to outdoor monitoring, we also selected 19 homes near these sites, 23 borough-matched offices and 7 sports centers for investigation of indoor/outdoor relationships. Air samples were collected for 14 days by Ogawa passive samplers indoors and outdoors simultaneously in each location. Indoor and outdoor NOx emissions sources and activities were collected by questionnaire survey and continuously monitoring on potential hot spots of emissions. The study was conducted during June-October, 2009.

Results－Mean outdoor NOx concentrations at 19 traffic sites were significantly higher than 21 urban background sites. The NOx concentrations at traffic sites and urban background sites were 39.7 ppb and 26.4 ppb during the study period. On the other hand, the NO2 concentrations at traffic sites and urban background sites were 21.2 ppb and 18.4 ppb respectively. On the aspect of vertical profile of NOx, a decrease in both NOx and NO2 concentrations with increasing height was found. The NOx and NO2 concentrations at 4th-6 th floors of 11.1-17.5 m high were 0.79 times and 0.75 times lower than the concentrations at 1st-3 rd floors of 1.5-7.9 m high, the NOx and NO2 concentrations at 7th-8 th floors of 20.7-23.9 m high were 0.64 times and 0.67 times lower than the concentrations which at1st-3 rd floors of 1.5-7.9 m high, respectively. We also completed air sampling at the location of 19 kitchens, 14 bedrooms, 9 living rooms, 23 offices, 7 gyms, 7 courts, 7 swimming pools, and their matched outdoor locations. Mean NOx and NO2 concentrations in kitchens (38.0 ppb and 22.8 ppb) and swimming pools (48.0 ppb and 24.0 ppb) were significantly higher than outdoor concentrations. By contrast, the concentrations in offices (18.7 ppb of NOx and 12.0 ppb of NO2) were significantly lower than outdoor concentrations. Mean indoor/outdoor concentration ratios were 1.47 in kitchens and 2.03 in swimming pools for NOx and 1.28 in kitchens and 1.54 in swimming pools for NO2. We identified indoor NO2 concentrations were significantly increased by opening windows in bedrooms. We also found NOx concentrations were marginally increased by using LPG as a cooking fuel in kitchens. There is a concentration gradient of NO2 away from boilers near swimming pools.

Conclusions－NOx emissions from outdoors and indoors, such as stove in kitchens and boilers near swimming pools, contributed to elevated NOx concentrations in all indoor microenvironments of homes and sports centers respectively.

並列關鍵字

Nitrogen oxides (NOx) ； Nitrogen dioxide (NO2) ； Indoor air quality (IAQ) ； Vehicle emissions ； Spatial distributions

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