Cover letter enclosing air quality reports, Trinity Place, Jan 2002

NYC 9/11 Public Portal Document

09/28/2001 10:14 6315903195 ENVIROSCIENCEC SLTAN PAGE 03

Arner can Stock Exchange,28 Saptenibr 2001 centimeters) to produce the asbestos air concentration. The NIOSH 7400 or 7402 methods used by OSHA to evaluate worker exposure results in values of fibers per cubic centimeter. Fibers greater than 5 micrometers in length and greater than 0.25 micrometers in diameter are counted. Structures counted in AHERA include the fibers in the NIOSM OSHA approach and includes much smaller structures. So the AHBR.A, air concentration presented in the attached tables are more protective than the NIOSH OSHA approach

Samples that met the U.S. EPA AHERA clearance criteria of 70 structures/square millimeter are considered acceptable and are considered safe for reoccupancy.

The 9* floor has tines samples (Room, 909, Cubical 49, and Cassaleggt room) that exceed the U.S. EPA AJWRA, clearance criteria of 70 •structures/sgaare millimeter and one that approaches the clearance criteria ( Cubical 52). Cubical 39 has a value of 37.88. These results are less than the OSHA PEL of 0.1 fibers per cubic centimeter.

We believe the asbestos in the air in these areas is due to the catastrophe and we do not believe that the asbestos was from the 22 Thames building because of the residue from the explosions and collapse was found in significant quantities on this floor and because the other results in 22 Thames and 86 Tufty Place are so low. Other floors such as the 6e lf oor also had significant quantities of the residue from the explosions and collapse. On September 23, 2001, we recommend that the floors in 22 Thames that had not been tested be tested. This sampling was completed on September 241 2001.

Outdoors samples were collected an the 45' floor, and the 91 floor. These samples were all less than detectable limits. These outdoor samples may be compared with the U.S. EPA collected asbestos air monitoring locations Lower Manhattan that are presented on www.epa.gov/epahome/datarnap02.h!m.

Asbestos bulk samples were collected on September 20x` and September 24x. Dust samples were collected from exterior window ledges and different sites where material was available inside the building. All samples collected are net considered asbestos contaiHug material since they contain less than one percent asbestos. The Asbestos bulk sample results presented in the attached tables. are

The asbestos clean up must be conducted by New York State and U.S. EPA certified asbestos abatement contractors and workers. The general cleaning protocol once gross debris has been removed is to HEPA vacuum, followed by an amended water wash, followed by HEPA vacuuming. Porous surfaces such as carpets, f rniture, ceiling tiles (and support grids), office partitions, and other soft goods must be evaluated for the feasibility of cleaning. If surfaces can not be cleaned they must be discarded. The electrical equipment must be evaluated and specially cleaned or discarded.

The asbestos cleaning started with the floors most needed by the American Stock Exchange and proceeded to other floors on a priority basis. Asbestos fibers from outside the building and from the 9s' floor of 22 Thames have not appeared to migrate to the other floors because the samples collected on later

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