NYC 9/11 Public Portal Document
dvanced Environmental Corp.
September 17, 2001
Mr. William Dacunto
Managing Director of Operations
Silverstein Properties
140 Broadway
New York, New York 10005
Re: Asbestos Air Monitoring, 120 Wall Street, New York, NY
Dear Mr. Dacunto:
On September 16, 2001, Advanced Environmental Corp. performed air monitoring within various tenant
floors within the above referenced building. Samples were collected within these floors to document the
asbestos fiber concentration levels of the ambient air.
A total of eight (8) samples were collected and analyzed using the Transmission Electron Microscopy
(TEM) method according to the EPA AHERA protocol. TEM with energy dispersive X-ray analysis is an
analytical method that enables a fibers chemical composition to be identified.
At the present time, there are no non-industrial indoor air quality standards, or permissible exposure limits
for airborne asbestos. This fiber specific protocol is generally utilized to determine clean air following a
"large" abatement project. TEM sample analysis detects filter loads (the number of structures detected per
square millimeter of collection media surface) which, if less than or equal to EPA-AHERA release criteria
of 70 structures per square millimeter (s/mm2), determine whether or not the area is safe for re-occupancy.
A review of the analytical data shows, no structures were detected on all samples collected within 120
Wall Street, which is well below the EPA-AHERA release criteria of 70 s/mm2.
In conclusion, the TEM sample analysis data show acceptable concentrations of fibrous materials in the
am Tent air.
If ou ave any questions or need further clarification on air sampling methodology, please call me.
Sincerel
Robert uorro
Principal
1018.003
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