How does UV sterilizes fume hood

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Apr 18, 2011
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Is that true that there is a tendency not to use UV light anymore for hood sterilization because of low efficiency (would not sterilize hidden places not reached by the UV rays) and hazard to users? Is 70% EtOH and turning on the blower in advance enough?

Thanks,

Eduardo

8 Comments

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mchlbrmn 10 months ago

I've read that recommendation, but haven't noticed anyone following it. The reason I heard cited was that the bulbs over time lose their intensity and effectiveness, and also the safety. I can't see ethanol reaching more surfaces than UV, but I think technique and a good hood are the main factors. Ethanol (or other disinfectant) should be used in addition to UV also to get surfaces covered by any stuff in the hood and to back up the UV.
Years ago I once tested a hood (not in the TC room) by spreading E coli on a plate and shading portions of the plate for progressive times. For that strain of E coli, and that bulb that day, the UV was very effective and killed everything within a few minutes.

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mediaflak 10 months ago

Wait... how harmful is the UV to the lab technician? I'm normally only exposed at most 5 seconds when I walk into the Tissue Culture Room to turn off the UV lights.

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relaxin 10 months ago

Five second exposure to UV light should not be a big problem, since you wear long sleeve labcoat and gloves.

I once knew a graduate student who looked at the ethidium bromide-stained agarose gel on the UV transilluminator (without a face shield!!!) for such a long time that he got sunburn on his face. He did have safety goggle for protecting his eyes.

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relaxin 10 months ago

The UV light is inside the hood, and the switch is on the outside. You hands are not exposed to UV light.

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Roberto Rosati 10 months ago

I don't know if it's MediaFlak's case, but some facilities have ceiling UV lights.

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relaxin 10 months ago

Even if the UV light is on the ceiling, the light switch should be outside of the culture room. It will be stupid to have someone to walk inside the room to turn off the UV light.

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mchlbrmn 10 months ago

In my lab when the hood is not in use the UV is always on and the hood open about 20 cm even when people are in the room. The UV light falls directly on a chair and the floor (and bleaches the chair and discolors the floor wax (tragic)). The glass should be UV opaque, but light could reflect off the metal of the hood surface upward(?). I doubt it does much, but I remember hearing that you can get sunburn at the beach from light reflected off the sand. Also, if one leans over under the hood to turn off the vaccuum line from the valve under the hood, one is exposed to the UV briefly.
Does MediaFlak and others' labs turn off the UV inside the hoods when people are in the room?

I think a main complaint I read about UV was that the lamps get weak later in their lifespan and the sterilizing ability is weakened.

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arpitkakkar1 10 months ago

You should try to prevent your self from uv rays because it bring skin diseases.