[ RadSafe ] HEPA filters for radioisotope fume hoods

[Raymond Ilson]

Hi Peter:

We also have HEPA filters in the exhaust train of most of our laboratory "fume" hoods. In the great majority of cases they serve no purpose, as you have noted.
Many years ago I approached each of our safety functions (envir/hygiene/rad) about this and  all agreed that they serve no purpose with the possible exception
of some geology labs. Perhaps a few hoods in a building could be dedicated to any work requiring such a filter.

Biological cabinets/laminar flow hoods are a different matter.

Regardless of this, the Facilities and Services management would not remove them. They cited the need to rebalance the systems etc - despite the obvious cost
savings of removing the filters and cutting back on the power demands of the exhaust fans. They even quoted the famous "we've always done it this way".

My other concern is with the safety of the staff who must remove these filters when they become so dirty that the exhaust becomes inefficient. At that point,
some poor building engineer must climb a ladder and remove the filthy filter with considerable difficulty and some danger because this is overhead work. At that
time, PPE must be worn because the layers of dust and other materials (kimwipes etc) on the filter may have become contaminated with condensates and the filter
is thus an exposure and waste problem! In spite of this, the filter is then replaced (~$80 each?) and so on and so on  ......

Common sense seems to elude us on this one!

Ray



Peter.Vernig at med.va.gov wrote:

> Somebody not too long ago, say 1 to 3 years informed me why so many places
> have HEPA filtration of fume hoods where radioisotopes are used.  In
> virtually all research situations dispersible powered radioactive material
> is not used so HEPAs make no sense.  I have seen them at NASA's Ames
> Research Center and UC Berkeley both institutions should know better.
>
> My recollection is that it was a building code or "best practice" that some
> ill advised agency put into place.  If the person that sent me the
> information or anybody else knows about it I would greatly appreciate
> getting it retransmitted to me.  I have just discovered such an arrangement
> and in order to kill it, it would be very helpful to know the source of the
> practice.
>
> Any opinions in this e-mail are solely those of the author, and are not
> represented as those of the VA Eastern Colorado HCS, the Dept. of Veterans
> Affairs, or the US Government.
>
> Peter G. Vernig, Radiation Safety Officer, MS-115, VA Eastern Colorado
> Health Care System, 1055 Clermont St. Denver, CO 80220,
> peter.vernig at med.va.gov, Phone= 303.399.8020 x2447; Fax = 303.393.5026,
> alternate fax, 303.393.5248
>
> "...whatever is true, whatever is noble, whatever is lovely, whatever is
> admirable, if anything is found to be excellent or praiseworthy, let your
> mind dwell on these things."
>
> Paul of Tarsus
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