Effectiveness of a Portable, Large-Area Ultraviolet Germicidal Device

Effective disinfection of the hospital environment is a key component in the prevention of healthcareassociated infections. The objective of this project was to evaluate the effectiveness of an ultraviolet germicidal device in reducing the concentrations of culturable bacteria on indoor surfaces. The ultraviolet germicidal device was installed and operated in four experimental trials conducted in a microbiology research chamber. Agar plates inoculated with known concentrations of two test microorganisms were placed on benches inside the chamber at two distances, 1.5 meters and 3.0 meters from the machine, for exposure times of 5 minutes, 10 minutes, and 20 minutes. With test agar plates directly exposed to ultraviolet radiation, percent reductions were all >99.9% compared with the laboratory control plates. However, with indirect UV exposure, the edge of the plastic petri dishes provided some protection from the UV source, as indicated by the presence of colonies along the edge of the agar plates. Additional research will be conducted to further characterize the device for optimal use in surface decontamination and to determine its effectiveness in reducing airborne culturable bacterial concentrations.