E-mails 2002 M. Gilsenan

NYC 9/11 Public Portal Document

• Final Report 125 Cedar Street, NYC, NY

AIR MONrromNc

Sample Collection

ATC collected samples of air on 25 millimeter, mixed-cellulose ester filter membranes (0.45 micron pores) contained in manufacturer pre-assembled, three-piece cassettes with electrically conductive, extended cowls. Pump flow rates were determined (both at the start and at the end of the sampling period and periodically by a representative of the NYCDEP) with a secondary standard (rotameter) that is calibrated quarterly against a primary standard (Gilian Instrument Corporation primary flow calibrator "Gilibrator"). Fibers from ambient air were collected with the filter cassette open-faced and positioned between three to five feet above the floor.

Sample Analysis

PCM ambient and clearance samples were analyzed by ATC's New York City laboratory utilizing the PCM method of analysis. The microscope used for sample analysis was equipped with a phase contrast condenser. Sizing and fiber counts were performed at 400X magnification. Samples were analyzed by the National Institute of Occupation Safety and Health (NIOSH) Method 7400 using method "A" counting rules. Method "A" rules count only those fibers that have a length greater than five microns and a length-to- width ratio greater than three-to-one. All air sample results are reported in fibers per cubic centimeter of air (f/cc).

TEM ambient air samples were analyzed by ATC's New York City laboratory under strict AHERA protocol. TEM with Energy Dispersive X-ray analysis (EDX) involves subjecting the prepared filter media to a stream of electrons. The returning diffraction pattern is a signature for the elemental composition of the material. This allows for precise asbestos quantification.

Quality Assurance

Analysis was performed by personnel who have completed the NIOSH 582 Sampling and 'Evaluating Airborne Asbestos Dust course or an equivalent course.

Personnel also participate in the NIOSH/AIHA (American Industrial Hygiene Association) Proficiency Analytical Testing (PAT) Program to ensure consistency in methodology. All laboratory technicians involved in air sample analysis have received applicable EPA training.

Air Sample Results

Final air clearance samples reported concentrations of airborne fibers less than the concentrations required by the EPA for this project. The attached appendices contain all laboratory analysis information.

ATC Project No. 15.22906.0002 Page 5

NYC-WTC 000162625