a b s t r a c tAs the viral diseases such as Severe Acute Respiratory Syndrome (SARS) and Influenza A (H1N1) occur in many countries recently, the epidemic of those influenza viruses causes many human casualties. Moreover, the second infection from infected patients particularly within general hospitals frequently takes places due to improperly hospitalized and/or quarantined patients. Accordingly, it becomes a great concern to accommodate safer ventilation system in general hospital wards against such airborne transmitted viruses. It is also a recent trend that many urban general hospitals are designed and constructed as high-rises. If a virus is transmitted through uncontrolled air movement within a hospital and then infected other patients or healthy visitors, it might be impossible to control the spread of the disease. Thus research has been preceded scrutinizing stack effect on the indoor airborne virus transmission in large hospitals by conducting both the field measurement and numerical analysis according to the outdoor temperature and the releasing vertical points of the tracer gas assumed as a viral contaminant. In the field measurement of a high-rise hospital, the indoor airflow was affected by the stack effect of vertical chute of the building. The numerical simulation was verified by comparing its prediction results and the field measurement data. In result, very high possibility has witnessed that the airborne contaminant emitted from the infected patients in the lower floors could be transported to the higher floors through the airflow driven by the stack effect.
Expected risk of infection from patients to healthcare workers in an AIIR was found.• We investigated how to remove airborne contamination effectively in AIIRs.• Both full-scale field experiments and CFD simulations were performed. • Transport of gaseous pollutants is indicated by tracer gas.• By changing the exhaust air flow, the exposure pollutant level was significantly reduced.
A B S T R A C TThis study, that is practice-based learning in a real hospital construction project, has evaluated the ventilation performance of three strategies in the protection of health care workers and HVAC control for airborne infectious diseases induced by contaminated exhaled air from patients in a negative pressure isolation room. This paper examines air flow path and airborne pollutant distribution by computational fluid dynamics modeling and field measurement. In hospitals, the risk of virus diffusion mainly depends on air flow behavior and changes in direction caused by supply air and exhaust air locations. An improved isolation room ventilation strategy has been suggested, and is found to be the most efficient in removing contaminants based on the observations and simulation results from three ventilation systems. The results show that ventilation systems utilizing the "lowlevel extraction" technique are very effective at removing pollutants in the human breathing zone. A new clean isolation room ventilation strategy has been developed that employs two exhaust air grilles on the wall behind the bed at low floor level, coupled with a fan filter unit, and is found to have the highest pollutant removal efficiency.
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