Air sampling results letter, Dec 2001

NYC 9/11 Public Portal Document

ENVIROSCIENCE CONSULTANTS, INC. 2150 SMITHTOWN AVENUE RONKONKOMA, NEW YORK 11779-7348 PHONE:(631) 580-31 91 • FACSIMILE (631) 580-3195

B. GALLAGHER P. DERMOOY C. GILBERT, PH.D. T. KLUENDER E. DETWEILER G. NEUSCHWENDER 18 December 2001 J . DRISCOLL G. MENEGIO L. SAVARESE

Ms. Carol Hoover, Assistant to the Chairman American Stock Exchange 86 Trinity Place New York, New York 10006-1872

Subject: December 2-3, 2001 Air Sampling Results for the SIAC, American Stock Exchange, New York, NY.

Dear Ms. Carol Hoover:

This report includes the results of air sampling conducted 20:22 hours December 2 through 21:31 hours December 3, 2001. The air sampling locations and results are reported below. Asbestos samples were collected according to New. York State and U.S. EPA standards and analyzed according to U.S. EPA standards using Transmission Electron Microscopy. Other substances were collected and analyzed using the National Institutes for Occupational Safety and Health protocol.

Based on our experience and direction from U.S. EPA and the New York State Department of Labor we recommend that those 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 U.S. AHERA regulations were developed to protect all children, faculty, and staff in schools from asbestos exposure. The two different methodologies, U.S. EPA AHERA methodology, and OSHA used methodology differ from the beginning of the protocol. The U.S. EPA uses 70 structures per square millimeter (s/mm2 ) as the value considered safe for school reoccupancy by children, faculty, and staff after asbestos abatement. The AHERA protocol requires an electron microscope with a magnification of 20,000 times. The electron microscope in our laboratory is capable of measuring up to up to 480,000 times. The NIOSH 7400 method may use a phase contrast light microscope with a magnification of up to 400 times. * The NIOSH 7402 method uses an electron microscope. AHERA allows a blank filter to have up to 70 structures per square millimeter. Structures are fibers, clusters, bundles, and matrixes that contain asbestos fibers greater than 0.5 micrometers in length. If the average work area samples are found to have less than the 70 s/mm2 no further action is required. If the samples are found to be greater work area than 70 s/mm2 then the asbestos air concentration outside the work area is compared with the technique or the work area may be re-cleaned and air concentration and subjected to a Z-Test statistical area and divided by the air volume the air re-sampled. The filter concentration is multiplied by the filter sampled (in cubic 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 NIOSH OSHA approach and includes much smaller structures. Therefore, the AHERA 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. ENVIRONMENTAL & INDUSTRIAL HYGIENE CONSULTANTS WWW.ENVIROHEALTH.ORG

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