title: Sterilization efficiency of the photocatalyst against environmental microorganisms in a health care facility.
abstract: The photocatalyst equipment consists of a titanium dioxide membrane and an ultraviolet lamp. The authors studied if the photocatalyst equipment is practically useful in sterilizing environmental microorganisms in the health care facility. The number of microorganisms was compared in the cases of no sterilization (control) and the photocatalyst sterilization. As a result, a statistical difference was observed between control and the photocatalyst sterilization against airborne microorganisms (p < 0.01), but not against surface microorganisms (p > 0.2). The photocatalyst uses an air sucking system, so it may be ineffective against microorganisms tightly attached to surfaces. However, the effectiveness of the photocatalyst to sterilize airborne microorganisms in the health care facility was successfully confirmed. Concerning the humidity effect on the photocatalyst sterilization, the authors compared the number of airborne microorganisms in cases of the control, UV alone and photocatalyst sterilization when humidity was changed. A statistical difference was observed between UV and the photocatalyst sterilization (p < 0.01) when humidity was increased to 60-70%, but not observed between UV and the photocatalyst sterilization (p > 0.2) when humidity was not controlled and was around 10-20%. This indicates that maintaining high humidity levels will present satisfactory sterilization results due to a greater production of OH radicals. From data obtained, no effect of the adsorption on the TiO2 membrane could be observed.
authors.affiliation: National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya, Tokyo 158-8501, Japan.
authors.forename: Hideharu
authors.initials: H
authors.lastname: Shintani
authors.forename: Sinobu
authors.initials: S
authors.lastname: Kurosu
authors.forename: Akiko
authors.initials: A
authors.lastname: Miki
authors.forename: Fumie
authors.initials: F
authors.lastname: Hayashi
authors.forename: Shigekazu
authors.initials: S
authors.lastname: Kato
mesh_terms: D000327:Adsorption; D000391:Air Microbiology; D001419:Bacteria / Q000302:isolation & purification / Q000528:radiation effects*; D002384:Catalysis; D003428:Cross Infection / Q000517:prevention & control*; D004783:Environmental Microbiology; D006761:Hospitals / Q000592:standards; D006801:Humans; D006813:Humidity; D010777:Photochemistry / Q000295:instrumentation; D013242:Sterilization / Q000295:instrumentation / Q000379:methods*; D014025:Titanium / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: C009495:titanium dioxide; D014025:Titanium