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Ultraviolet germicidal irradiation (UVGI) systems have been considered as a possible solution to prevent microbial contamination in air handling units (AHUs) which are known to be a potential cause of respiratory diseases for building occupants. However, as it would be time-consuming and costly to verify the germicidal effect of UVGI systems using conventional culture media method in the field, this study used a fungal biosensor developed from a biosensor originally developed to assess indoor climate. The experiments were performed to verify that UVC radiation on the fungal spore of the biosensors at various doses led to measurable differences in spore hyphal length after subsequent spore incubation. The retardation of hyphal length growth can be taken as a measure of fungal susceptibility to UVC radiation exposure. The results showed that Eurotium herbariorum produced no hyphal growth after 1,400 J/m2 of UVC exposure, and that hyphal length for Alternaria alternata was significantly reduced. The same experiment was then repeated for done for Cladosporium herbarium and Fusarium solani – fungal species frequently detected in AHUs. The results showed that UVC levels of approximately 10,000 J/m2 were needed to retard C. herbarium hyphal growth, though even a comparatively low UVC dose was enough for F. solani. To demonstrate the applicability of the fungal biosensors to AHUs in the field, they were attached to the coil and the drain pan of an AHU with a UVGI system installed and then exposed to UVC for one hour. After incubation for three-days, the hyphal lengths observed, especially those of F. solani, corresponded with UVC doses of 468-1,620 J/m2 at each sampling point. Since fungi are usually more resistant to UVC irradiation than otherinfectious microbes or viruses, it can be assumed that fungal biosensors are an effective index of evaluating the overall germicidal effect of UVGI systems.
Citation: IAQ Conference: IAQ 2010: Airborne Infection Control
Product Details
- Published:
- 2011
- Number of Pages:
- 7
- File Size:
- 1 file , 440 KB
- Product Code(s):
- D-IAQ2010-C136-10
