Asbestos testing summary letter, Feb 2002

NYC 9/11 Public Portal Document 02/20/2002 09:34 FA% 075

Summary ofAsbestos Sampling Results Page2of3 Address,100 John Street Date sampled:Dec 3, 2001

Results ofPhase Contrast Microsco testing ofair at 100 John Street Dec. 3 2001 Sampled Outside Common Residence A Residence 2 ple Numbers A-O27 A-C-27 A R1-27 A R227 ofFibers(f/cc)* at <0.001 <0.001 <0.001 <0.001 r

John Street Concentration of Fibers (flee) in <0.001 to .001 <0.001 to 0.002 <0.001 to 0.003 <0.001 to 0.003 canspa=ison locations NYC Re-occupancy Standard 0.01 0.01 0.01 0,01 (f/ce)•* • flee Is fibers in each cubic centimeter (cc) of air. This is calculated from the number of fibers seen on the air filter and the volume of air pulled through the filter measured in cubic centimeters of sir. ** New York City Department of Environmental Protection asbestos clearance criteria for post-abatement work (Rotes of the City of New York, Title 15, Chapter 1)

ASBESTOS DUST TEST RESULTS

In general, the dust and debris samples were examined by two different laboratory methods for asbestos fibers, Polarized Light Microscopy (PLM) and Transmission Electron Microscopy (TEM), PLM is used to define asbestos containing material in dust and debris. A material is considered to be asbestos containing material if it contains more than 1% asbestos using the PLM method. The PLM method only counts the larger asbestos fibers. Therefore, if results by PLM were not greater than 1% asbestos, the sample was then analyzed by the TEM method that does count the smaller fibers. However, TEM analysis is not used for regulatory purposes for dust samples.

No asbestos fibers were found in the dust samples by the PLM laboratory method. Further analysis by the TEM method detected asbestos at levels of less than 1% in the dust outside, the common area, and one of the residences.

Fibrous materials in dust found by PLM analysis: Polarized Light Microscopy identifies asbestos fibers by shape and optical characteristics. Other fibers such as fabric (synthetics), paper (cellulose) and fiberglass may be identified in the analysis. The laboratory analyst counts the fibers present to give an estimate of fiber content. PLM is used for regulatory purposes for dust samples.

-15

NYC-WTC 000123872