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

He, Yao; Xing, Yu-bin; Ni, Bin; Jiang, Yong; Suo, Ji-jiang; Zhong, Guang-lin; Chang, Qing; Jiang, Bin

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.