目標：瞭解我國長期照護機構空氣中細菌菌落濃度的分佈特性，以及影響細菌暴露的環境因子。方法：針對台北市五家長期照護機構進行密集的環境採樣，測量空氣中可培養性細菌菌落濃度及室內空氣品質因子，並利用統計模式評估影響室內細菌濃度的環境因子。結果：五家機構室內總菌落濃度平均值為282-812 CFU/m3，部分機構的平均濃度已超過環保署空氣品質建議值500 CFU/m3。最常出現的細菌類型為球菌及桿菌；革蘭氏陰性菌的濃度皆高於陽性菌。部分機構空調及通風系統出風口菌落濃度高於室內濃度，顯示空調及通風系統為微生物污染的可能來源之一。根據多變項迴歸分析結果，採樣日期(平日、假日)、採樣時段(上、下午)、機構別、有無使用空氣清淨機、二氧化碳濃度、採樣點人數等因素和菌落濃度有顯著相關。結論：各機構由於建築特性、通風量、機構內人數、清潔方式與頻率有所差異，室內微生物濃度的分佈亦不同。若機構能有效控管環境品質，應能大幅降低疾病的發生與傳播。

Objectives: This study investigated the characteristics and determinants of airborne bacteria in long-term care facilities in Taiwan. Methods: We did intensive environmental samplings,including airborne culturable bacteria and major indoor air quality factors, in five long-term care
facilities in Taipei. We used statistical models to evaluate the environmental determinants of the levels of indoor bacterial colonies. Results: The average total bacterial colony concentrations in the study facilities ranged from 282 to 812 CFU/m3. The mean bacterial colony concentrations in several facilities exceeded 500 CFU/m3, the maximum level recommended by the Taiwan Environmental Protection Administration. Bacilli and cocci were the dominant bacteria in the study facilities. The concentrations of Gram-negative bacterial colonies were higher than those
of Gram-positive bacteria. In some study facilities, the bacterial colony levels near the diffusers of AC (air conditioner) or HVAC (heating, ventilating and air conditioning) systems were higher than indoor concentrations in general, indicating that AC and HVAC systems might be potential sources of microorganisms. According to the results of multiple regression models, sampling time, different facilities, using an air cleaner or not, carbon dioxide levels, and number of people were significantly associated with indoor bacterial concentrations. Conclusions: Building characteristics, ventilation rate, number of people, and cleaning method and frequency were essential factors influencing indoor microbial distributions in long-term care facilities. Effective environmental control can reduce disease transmission and protect the health and safety of residents and staff in long-term care facilities.