Expert: Michael Anisfeld - 7/16/2007

Question
Dear Sir,

Our company design and manufactures Pass Boxes for Cleanrooms.  Recently we have been asked to produce chambers for Decontamination in Level 3 BSL Labs.  These chambers have been designed to work with VHP systems, and so far the results have been very positive.

We have just recevied a request to provide a Pass Box for a BSL Lab, using UV lamps as the method for decontamination.  The unit is being designed with UV lamps on the top and bottom of the chamber.  The internal surface will be #8 mirror finish to provide a reflective surface for the UV radiation.  The specimens (whcih we have no information on) will be suspended from a rack, so in theory the specimen will be exposed on all sides.  

My concern is that there is little penetration from the UV, so if there are any hidden surfaces on the specimen, the UV affect will not acheve the expected result. Cost may be factor in the request for UV as a decontamination source.

Do you have any recommendations as to how we may be able to supple an alternatice to UV without the high cost of a VHP system.

Regards
Steven Sewell  

Answer
Steven:

UV lamp pass-throughs have been long ago abandoned in the US and Europe as effective sterilization for materials in the pass-through (Indian companies still seem to believe in it!). It's not just "hidden" surfaces that are a worry, but any shadow or other interference with 'line-of-sight' hinders the process. Additionally it is almost impossible to validate UV lamps in this usage.

VHP is great, but seems to be just as effective as surface sanitizing with swabs (70% IPA).

I hope this helps.