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respirable criteria -Reply
>NESHAPs sets release limits based on dose. We operate in a dusty
>environment where the dust is visible. It seems reasonable that we
>could justify eliminating non-respirable particles from our release
>values. Does anyone know if this is prohibited? Also, I've seen
>references to respirable cut off values between 2.5 and 5 microns
>although I've seen HP limits at 10 microns. Does anyone know what the
>EPA could live with? ...
Let me take a quick shot at this. The weekend beckons, and its call is
My guess would have been that WIPP was governed by NESHAPS
subpart H, not I. (I also believe subpart I is still with us, but that it no
longer applies to NRC licensees). For the sake of argument, let me
assume NESHAPS applies.
THE NESHAPS limit is based on dose, but not just the dose from
inhalation. Non-respirable particles can still contribute to the dose via
other pathways. As such, I don't see how you could ignore them.
I am not familiar with CAP88, which can be used to demonstrate
compliance with NESHAPS, but I would be surprised if it doesn't permit
the use of site specific AMADs. (I know one version of AIRDOSE had
some flexibility in this area).
WRT what is respirable. You are right when you say that the term is
used in various ways. Respirable sometimes means those particles that
will make it into the pulmonary region of the respiratory system, for
which the cut-off is about 3 um. But, the cut point for particles getting
into the tracheobronchial tree (a legitimate part of the lung) is 10 um. I
suppose you could argue that particles larger than 10 um do not pose an
inhalation hazard but they can lead to a dose via other mechanisms.
Aside from entering the food chain, they can be inspired, end up in the
nasopharynx, and be swallowed.
The only nuclear facility that screens out particles above 10 um that I
have heard of is Argonne in their environmental air sampling. I don't know
the justification (assuming they actually use PM-10 samplers) but I would
guess that they assume that the radioactivity is associated with smaller
particles and that screening out the larger non-radioactive stuff reduces
filter loading - just a guess, likely incorrect.
It would be nice to hear about NESHAPS from some folks who have
actually had to implement it - I ain't got nuttin but book larnin on this one.
Have a good weekend
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