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Materials of many types are degraded by ultraviolet light from the Sun. UVA and UVB energy at the Earth’s surface is the subject of field of weathering testing, for which standards have existed for decades. UVC energy, however, is filtered out by the Earth’s atmosphere and therefore has not been studied as extensively in material studies. UVC energy has been extensively studied for its disinfection properties. Due to its short wavelengths and high absorption, the UVC band severely damages living cells by attacking DNA and RNA. Relatively small amounts of UVC energy kill viruses, bacteria, and fungal spores, and this is of obvious interest in the pandemic era. UltraViolet Germicidal Irradiation (UVGI) devices are being implemented at a rapid pace, and this raises concerns about material degradation from UVC exposures.
UVGI devices primarily use low pressure mercury lamps, which emit about 90% of their energy at a very narrow band centered around 254 nm. These lamps are often called UVC or germicidal lamps, and they are not a new technology. Fluorescent lamps of all types are low pressure mercury lamps with a phosphor coating on the inside of the glass tube which absorbs the 254 nm energy band and “fluoresces” or emits light at higher wavelengths. Depending on the phosphors used, the emitted light can be in the UVB, UVA, or visible regions of the spectrum. UVC lamps simply omit the phosphors, and this has no effect on the electrical properties or requirements to operate the lamps.
Materials designed to withstand natural sunlight, direct or through window glass, may not perform as well when exposed to UVGI devices. There is growing concern that everyday products may fade, turn yellow, become brittle, or experience other unexpected degradation in locations that are frequently disinfected by germicidal lamps. This webinar will define the problem, discuss two standard tests for UVC exposures, and explore potential standardization around an adaptation of a common weathering device, fluorescent UV weathering chambers such as the QUV. These devices have utilized fluorescent lamps to simulate terrestrial UVA and UVB exposures since 1970, and a new model, the QUV/uvc has been designed to simulate UVGI exposures of materials. The discussion will include initial thinking on correlating tests in a QUV/uvc with the effects of repeated UVGI exposures over weeks, months, or years.
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This webinar will be presented in English. A recording of the webinar and the slides from the presentation will be made available at the conclusion of the event. Please register for the event to ensure you receive the notification when these materials are available.