To evaluate the effect of the ultraviolet (UV) disinfection system on controlling microorganisms on the surface of medical devices, it is essential to measure the intensity of UV radiation intensity. However, a sensor that can easily measure it has not yet been developed. Thus, we developed a new sensor that can measure the UVC radiation dose, and conducted a study to clarify the detailed UV dose and effective microbial inactivation conditions by the UVC irradiation device that have been practically used. A UV irradiation sensor consisted of a zinc oxide photoconductive element and multi-logger acquisition software was developed in collaboration with a company. The UV irradiation sensors were installed at several locations in the model hospital room including frequently touched areas, environmental surfaces and blind spots. The UVC radiation intensity was measured simultaneously and continuously at multiple locations. Radiation intensity varied with distance and height even in the effective radiation range of the device, and attenuation was significant in blind spots such as upward direction and shadows. Our results indicated that the effectiveness of UV radiation varies depending on the radiation location.
