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Does a medical air cleaner require UV Light? According to the U.S. Centers for Disease Control & Prevention (CDC) Guidelines, "The use of UV lamps and HEPA filtration in a single unit would not be expected to have any infection-control benefits not provided by the use of the HEPA filters alone". http://www.cdc.gov/mmwr/preview/mmwrhtml/00035909.htm 1Because the clinical effectiveness of UV systems varies, and because of the risk for transmission of M.tuberculosis if a system malfunctions or is maintained improperly, UVGI is not recommended for the following specific applications: 1. Duct systems using UVGI are not recommended as a substitute for HEPA filters if air from isolation rooms must be recirculated to other areas of a facility. 2. UVGI alone is not recommended as a substitute for HEPA filtration or local exhaust of air to the outside from booths, tents, or hoods used for cough-inducing procedures. 3. UVGI is not a substitute for negative pressure. The use of UV lamps and HEPA filtration in a single unit would not be expected to have any infection-control benefits not provided by use of the HEPA filter alone. The effectiveness of UVGI in killing airborne tubercle bacilli depends on the intensity of UVGI, the duration of contact the organism has with the irradiation, and the relative humidity (66,108,111). Humidity can have an adverse effect on UVGI effectiveness at levels >70% relative humidity for S.marcescens (135). The interaction of these factors has not been fully defined, however, making precise recommendations for individual UVGI installations difficult to develop. Old lamps or dust-covered UV lamps are less effective; therefore, regular maintenance of UVGI systems is crucial.
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