A Household Air-conditioner Adopting Low-Temperature Atmospheric Plasma (LTAP) for Sterilization of Airborne Microbes

Household air conditioners are widely used for conditioning air temperature and dehumidification in the cooling season. However, the airflow created by the air-conditioner may promote airborne transmission of microbes. To minimize indoor microbiological pollution, this investigation proposed integrating a low-temperature atmospheric plasma (LTAP) module into a household air-conditioner. To evaluate the sterilization of the airborne microorganisms, the integrated air-conditioner and LTAP module was installed to a test room. Escherichia coli (E. coli) was adopted as a surrogate of airborne microbes. Both the natural decay of the E. coli when switching off the LTAP module and the sterilization of the E. coli when switching on the LTAP module were measured. The ozone concentrations were monitored to evaluate the possible ozone exposure risk. The study found that the air-conditioner integrated with an LTAP module together with the natural decay sterilized 98.9% of E. coli in one hour. The averaged ozone emission rate was 2.5 mg/h and the resulted ozone concentration rise in a room with an infiltration rate of 0.7 air changes per hour was approximately 21 ppb. Notably, deposited dusts on electrodes can cause the ozone emission rate to increase remarkably.