Comparison between Hospital Single Air Unit and Central Air Unit for Ventilation Performances and Airborne Microbes

Ventilation performance in two units equipped with a single, hanging air conditioner having no filter, and another two units equipped with a central air conditioner with HEPA filter were compared for the air change rate, air velocity profile, and microbe concentration in a 814-bed public hospital from February to May 2006. It was found that microbe concentrations in units using a single air conditioner were about two times higher than those in central air conditioner units. Within the same type of air conditioner, increasing ventilation rate resulted in decreased microbe concentrations.