NYC 9/11 Public Portal Document
From: DeVoney, Danielle
Sent: Monday, April 01, 2002 11:58 AM
To: '[email protected]’; [email protected]:
[email protected]: Rodenbeck, Sven; [email protected] :
[email protected]: DeVoney, Danielle; [email protected] :
[email protected]: [email protected]: [email protected]:
[email protected] : [email protected]: Randi J.
Walker; Patricia M. Fritz
Cc: [email protected]: [email protected] :
[email protected]
Subject: draft screening levels for asbestos, FG and silica in indoor
air and settled dust
Importance: High
Hi-
Main points of discussion on these issues for today’s call are outlined below. I’ve tried to identify
the main technical issues, so we can reach consensus, or identify additional information we need
to consider on each point. I have included tiered screening values for fibrous glass which take
into consideration both dust and air levels. There are two versions of these screening levels
which take different approaches as outlined below. I thought this would be useful for the
discussion.
1) Sampling methodology for fibers. The microvac technique seems to be the most well
developed method. It is a written and approved ASTM method which would give us surface
loading information.
2) Use of K factors, or other techniques to extrapolate from settled dust to air screening values.
Questions:
a) Does the group feel Millette’s K factors are well enough supported to apply in this case?
b) What other options exist? (see “Dust Ideas 1 April.wpd” below)
c) Can K factors be applied to non-fibrous dust components?
3) What risk estimate should be used for asbestos screening values?
A straight 1 year continuous exposure scenario gives a screening values of 0.028 f/cc.
However, if this is based on sampling during daily activity, it may underestimate due to
episodic higher exposures.
Earlier screening level for this tier was set at 0.01 f/cc.
One option would be to use non-aggressive air sampling in conjunction with settled dust levels
and modeling of activity based episodic exposures for a combined risk assessment.
4) Sampling methodology and screening values for silica. We are still working on determining a
dust sampling method for silica. The sampling method should be defined prior to determining
a screening value for these data.
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AsbScreenDrlApril.wp
d
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AsbCalcslApril.xls
NYC-WTC_000164456
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