Question on Environmental Monitoring Filter Media

[Dale Dusenbury <dale.dusenbury@ncmail.net>]

    Does anyone on the list have experience with the use of 46.2

mm diameter Teflon filter disks in air monitoring for

environmental radioactivity ? One of our sister agencies supplies

us with 47 mm quartz filters collected from PM-10 samplers

throughout the State. Our laboratory counts them for gross beta

activity and performs gamma spectroscopy if the gross beta

exceeds a predetermined level.

    As a result of state budget cuts, some of these PM-10 sites

are being retired and replaced with PM-2.5(2.5 micron particulate

size)filters. This other agency has asked if they could supply us

with the Teflon filters from the PM-2.5 stations instead. I have

three questions:

    1. How can a laboratory acquire a mixed gamma standard for

efficiency determinations that uses a Teflon filter? Can private

companies produce them if you send them the filter disks?

   2. Are there any differences in specific effects between the

Teflon vs. the quartz filters(such as problems with dust loading,

self-absorption,loss of sample from surface etc.)?

   3. Are these Teflon filters strong enough to be collected by

technicians and sent through the mail?



You can reply to the list with my answer or to my personal e-mail

if you'd rather.. Thanks for your help!



Dale Dusenbury, CHP

Environmental Radiation Specialist

NC Division of Radiation Protection

3825 Barrett Drive

Raleigh, NC 27609-7221

e-mail:dale.dusenbury@ncmail.net



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