Comparative study of product contamination rates in class II biological safety cabinets with and without ultraviolet light disinfection

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Apiwat Lapamnouysup
Papon Ganjanasiripong
Anek Kaewpan
Thanaporn Chuen-im


Class II biological safety cabinets (BSCs) are equipment necessary in microbiological laboratories to protect workers from laboratory-acquired infections. The recommendation has dismissed the use of ultraviolet (UV) light in BSCs. Nevertheless, >80% of class II type A2 BSCs manufactured in the U.S. in the past decade were installed with UV light. This study aimed to determine the contamination rates of products in BSC working surfaces disinfected with UV light irradiation for 15 min and subsequently with 70% ethanol, and compared with those disinfected using only 70% ethanol. Results showed that the numbers of contaminated plates with bacterial and fungal colonies after disinfection with 70% ethanol alone were not significantly different from those after disinfection with UV light plus 70% ethanol. No significant difference in the numbers of contaminated plates was observed between BSCs in air-conditioned and window-ventilated rooms. Finally, the benefits and limitations of using a UV light system for the disinfection of working surfaces in class II BSCs were discussed.


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Biological sciences


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