Abstract
We developed 222 nm-UVC lamps for disinfection in occupied space. Since these lamps require an operation
lifetime of several thousand hours, such critical characteristics as radiation spectra must be investigated
after long-term operation. In this study, we investigated the output, spectral changes, and filtering
characteristics after long-term operation of filtered 222 nm-UVC lamps and confirmed just minimal changes
in the lamp spectrum even with continuous operation over 8000 h. We found no changes in the harmful
ultraviolet ratio: 235 ~ 320 nm integrated intensity/200 ~ 230 nm integrated intensity. Lifetime tests
continue, and a longer life expectancy is expected. We also explained the light distribution and dimming
functions of next-generation lamps. This new source has a wider light distribution, and dimming will
enable continuous operation. We anticipate that this will allow more effective infection control.
