title: Impact of Room Location on UV-C Irradiance and UV-C Dosage and Antimicrobial Effect Delivered by a Mobile UV-C Light Device.
abstract: OBJECTIVE To evaluate ultraviolet C (UV-C) irradiance, UV-C dosage, and antimicrobial effect achieved by a mobile continuous UV-C device. DESIGN Prospective observational study. METHODS We used 6 UV light sensors to determine UV-C irradiance (W/cm2) and UV-C dosage (µWsec/cm2) at various distances from and orientations relative to the UV-C device during 5-minute and 15-minute cycles in an ICU room and a surgical ward room. In both rooms, stainless-steel disks inoculated with methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and Clostridium difficile spores were placed next to sensors, and UV-C dosages and log10 reductions of target organisms achieved during 5-minute and 15-minute cycles were determined. Mean irradiance and dosage readings were compared using ANOVA. RESULTS Mean UV-C irradiance was nearly 1.0E-03 W/cm2 in direct sight at a distance of 1.3 m (4 ft) from the device but was 1.12E-05 W/cm2 on a horizontal surface in a shaded area 3.3 m (10 ft) from the device (P4 to 1-3 for MRSA, >4 to 1-2 for VRE and >4 to 0 log10 for C. difficile spores, depending on the distance from, and orientation relative to, the device with 5-minute and 15-minute cycles. CONCLUSION UV-C irradiance, dosage, and antimicrobial effect received from a mobile UV-C device varied substantially based on location in a room relative to the UV-C device. Infect Control Hosp Epidemiol 2016;37:667-672.
authors.affiliation: 1Quality Improvement Support Services,Yale-New Haven Hospital,New Haven,Connecticut.
authors.forename: John M
authors.initials: JM
authors.lastname: Boyce
authors.affiliation: 3Department of Laboratory Medicine,Yale-New Haven Hospital,New Haven,Connecticut.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Farrel
authors.affiliation: 3Department of Laboratory Medicine,Yale-New Haven Hospital,New Haven,Connecticut.
authors.forename: Dana
authors.initials: D
authors.lastname: Towle
authors.affiliation: 1Quality Improvement Support Services,Yale-New Haven Hospital,New Haven,Connecticut.
authors.forename: Renee
authors.initials: R
authors.lastname: Fekieta
authors.affiliation: 1Quality Improvement Support Services,Yale-New Haven Hospital,New Haven,Connecticut.
authors.forename: Michael
authors.initials: M
authors.lastname: Aniskiewicz
mesh_terms: D016360:Clostridioides difficile / Q000528:radiation effects; D004203:Disinfection / Q000379:methods*; D004307:Dose-Response Relationship, Radiation; D055624:Methicillin-Resistant Staphylococcus aureus / Q000528:radiation effects; D010362:Patients' Rooms; D011446:Prospective Studies; D014466:Ultraviolet Rays; D065507:Vancomycin-Resistant Enterococci / Q000528:radiation effects