经排风系统传播SARS可能性的示踪气体实验研究

目的 测定和分析某医院住院部病房楼空气流向及其与排风管道分布的关系并探讨和验证严重急性呼吸综合征(SARS)在医院感染可能的传播途径和影响因素。方法 在某医院住院部SARS输入病例所在病房卫生间燃放植物油熏香(示踪气体);为控制病房卫生间排风扇的开启、顶层抽风机的状态和病房新风系统等主要影响因素,共设计了6种实验状态。由4组实验员分别盲法到各楼层的4、5号病房采集、测量空气样本,并分别按10等分记分法评估其气味浓度。结果 在医院住院部8～13层的各病房均检测到示踪气体,在不同实验状态下,气体弥散的方向和浓度不尽相同。结论 医院目前的建筑结构和通风系统具备了病原体气溶胶自下而上经排风管道垂直传播的通道和空气动力学条件,示踪气体的分布与发病分布有一定的关联性。提示SARS存在气溶胶或其他载体形式长距离传播的可能性和证据,而在现有设施条件下,针对性的预防管理措施可在一定程度上阻断病原体经排风系统的传播。

Hypothesis on generating and tracer gas study regarding transmission of severe acute respiratory syndrome through ventilation system in a general hospital

OBJECTIVE: By measuring airflow and ventilation distribution of ward building, to explore and verify the hypothesis of airborne transmission and risk factor of severe acute respiratory syndrome (SARS) nosocomial infection. METHODS: Tracer gas (perfume of plant oil) was emitted to the bathroom of wards when SARS index patient lived. Six different experimental situations were designed to control the status of exhaust fan in bathrooms, exhaust fan in the top of building and fresh air exchange system. The concentration of perfume was separately measured by 4 groups of lab workers and recorded blindly by the scores of "tenth degree". RESULTS: Tracer gas was detected from the wards of 8th to 13th floor. CONCLUSION: Architecture and ventilation system of the inpatient building in the hospital contributed to the aerodynamic condition of SARS nosocomial infection through airborne transmission. The distribution of tracer gas in the wards was associated with SARS patients in this building. It was possible that SARS could have been transmitted to for distance by aerosol or other carriers.