台灣南部地區室內空氣中生物氣膠特徵之研究

室內環境中存在著許多會對人體健康產生危害之物質，懸浮於空氣中的生物氣膠為其中之一。生物氣膠泛指氣膠化之生物體或由其產生之物質，其包括細菌(如退伍軍人菌、大腸桿菌)、真菌(如黴菌)、病毒(如禽流感病毒、SARS病毒)與花粉等有生命之物體，以及不具生命之植物與動物之毛髮、皮屑等都是致病源及致病過敏源。台灣地處亞熱帶氣候區，年平均相對濕度高達80％以上，且夏天室外溫度高，造成室內長時間使用冷氣，而冬天因寒冷又緊閉門窗，易產生細菌和真菌等生物性污染物的滋生。台灣地域上之差異，也導致國內室內生物氣膠濃度分佈不同，南部的熱帶氣候區真菌濃度明顯較北部高，尤其以秋冬季節為甚。本研究篩選39家場所(包含醫療院所、學校、辦公大樓、大賣場、圖書館、車站及戲院)，先以簡易直讀式儀器進行區域性巡檢，各測定之場所依巡檢之結果，選擇一處具代表性之室內空間，以環保署公告之方法進行檢測。檢測結果顯示，第一類場所之二氧化碳濃度699~1022ppm(建議值為600ppm)、細菌958~3025CFU/m3 (建議值為500CFU/m3)，兩項檢測超標比例為100%；第二類所之二氧化碳為518~1182 ppm (建議值為1000ppm)，超標比例為14%、細菌為178~3183CFU/m3 (建議值為1000CFU/m3)，超標比例為43%及真菌為107~4500CFU/m3 (建議值為1000CFU/m3)，超標比例為29%。而二氧化碳濃度過高之原因，主要為室內人員過多而導致換氣率不足；細菌主要來源為室內人員本身、通風與空調系統中之濾網以及廚餘和垃圾之收集處；真菌主要來源為室外所影響。此外，為進一步了解二氧化碳與細菌是否有其相關性，本研究針對前述場所進行二氧化碳與細菌之相關統計分析，結果顯示為中高度相關(r=0.71)，統計之醫療院所也呈現中高度相關性(r=0.72)，意謂著室內人員密度越高則室內空氣細菌也會越高。另因南部秋冬季節之外氣真菌高於室內，本研究亦對高濃度超標外氣之真菌樣品進行菌種鑑定，四株優勢菌種三株為芽枝黴菌屬(Cladosporium)，另一株為鐮胞菌屬(Fusarium)。

關鍵字

細菌；真菌；室內空氣品質

並列摘要

The indoor environment is full of materials that are harmful to human health, and one of them is bio-aerosol. Bio-aerosols are aerosolized suspensions of organisms or organic matter, such as bacteria (Legionella pneumophila, E.Coli), fungi (molds), viruses (avian influenza virus, SARS virus), organic particles like pollen, dead plant, animal furs and hairs; these matters may become sources of lethal pathogens and allergens in some cases. Taiwan is situated in the sub-tropical climate zone with an average annual humidity of 80% and above. The high outdoor temperatures of summer seasons resulted in long term indoor usage of air conditioning, and coldness in winter produced poor ventilation due to closing of the doors and windows, all of which may contribute to growth of biological contaminants such as bacteria and fungi. The geographical differences in Taiwan also contributed to variations in the distribution of indoor bio-aerosol concentrations; the tropical climate regions in Southern Taiwan have significantly higher concentrations of fungi than Northern Taiwan, and the effects are even more pronounced during fall/winter seasons. This study has selected 39 locations (including medical institutes, schools, office buildings, supermarkets, libraries, train stations and cinemas) for data collection, starting with sectional readings taken from simple direct-measurement meters. Subsequently, a representative indoor space from each location was chosen for further testing, based on the initial results collected. The tests were then conducted in accordance with methods promulgated by the Environment Protection Agency. The test results showed that the concentration range of type 1 CO2 was between 699~1022ppm (recommended value: 600ppm), and the bacterial concentration was 958~3025CFU/m3 (recommended value: 500CFU/m3). The standards exceeding the ratio of these two tests was 100%; the Type 2 CO2 concentration was 518~1182 ppm (recommended value: 1000ppm) and the standard exceeding ratio was 14%; bacterial concentration was 178~3183CFU/m3 (recommended value: 1000CFU/m3) and the standard exceeding ratio was 43%; the fungal concentration was 107~4500CFU/m3 (recommended value: 1000CFU/m3), and the ratio was 29%. The main reasons for the overtly high CO2 concentration were due to excessive indoor personnel and inadequate ventilation; the sources of bacterial and fungal concentrations were from the indoor personnel, filters in the ventilation and air conditioning systems, kitchen waste and garbage collection areas. Additionally, to further investigate the relationship between CO2 and bacteria, the current study conducted statistical analysis on the CO2 and bacterial concentrations in the aforementioned locations. Our results showed a medium to high degree of correlation (r=0.71); similar statistical result was also obtained in medical institutes (r=0.72). Our results suggested that indoor airborne bacterial concentration may be positively correlated with indoor personnel density. In addition, because the outdoor fungal concentrations outdoors during fall/winter seasons in Southern Taiwan were often higher than those indoors, the current study have also performed initial strain identifications on the samples collected from outdoor sources of excessively high fungal concentrations. Out of the four dominant fungal species tested, 3 strains were indentified to be Cladosporium, and the remaining strain was the Fusarium.