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This is another great example of read the question
and answer the question. Although I found the dialog interesting, no one
answered the question.
"Do you know of any literature, which
scientifically deals with the question
of radon daughter removals by commercial air filters and especially dose rates to be expected near the filters and during changing the filters and possibly inhaling dust?" Ed Barratta came closest by stating an EPA document
once existed. But everyone else started with assumptions of the capture of the
Radon decay products and went from there.
I personally know of no documentation that has
studied the dose rates and contamination monitored on "Commercial Air filters".
I would like to know if the "commercial air filter" considered is the
over-the-counter type that is sold in bulk vs. a HEPA filter. That being
the wide difference in filtering capability. I have not seen a note
in commercial air filter literature that states its particle size
removal capability. This would greatly influence removal rates.
I do know that in my lab we have a normal over the
counter air filter (3M blue fuzzy- with a cardboard frame) and a HEPA filter
in-line in the exhaust air stream. These filters are routinely monitored for
dose and contamination levels. My lab performs
environmental analysis of soil, water, bioassay, and air filter samples
containing natural uranium and thorium together with their decay products.
The filters in the lab ventilation are surveyed
quarterly with the pre-filters replaced semi-annually. Yes, there are decay
products accumulated in the filter. The filters show levels of contamination,
but NO dose rate problems. The rad levels are routinely less than 25 uR/hr.
The filters are maintained for two weeks and surveyed again. At the two week
mark, the filter is below release levels for contamination and disposed of as
normal trash.
If someone else knows of documentation that
supports or disputes this, I would be interested in seeing it.
Dan Mackney
Technical Director for Radiochemistry
Waste Stream Technology
Buffalo, NY
716/876-5290
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