NYC-WTC_000208125

NYC 9/11 Public Portal Document

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104 East 25th St.. 10th Floor * New York. New York 10010 www.atc-enviro.com 212.353.8280 Fax 212.353.8306 ASSOCIATES INC.

April 4,2002

Mr. Bernard P. Orlan Director, Environmental Health & Safety New York City Board of Education 28-11 Queens Plaza North Long Island City, NY 11101

Re: Air Sampling for Silica P.S. ISOM 334 Greenwich Street New York, NY 10013 ATC Project No. 15-19125-0289

Dear Mr. Orlan:

ATC Associates, Inc. (ATC) is pleased to provide this report of air sampling for silica- containing dust conducted on March 18, 2002, at the referenced school. The New York City Board of Education (BOE) requested this sampling at the recommendation of Environ Corp., the consultant to the parents association.

SCOPE OF WORK

ATC conducted this sampling to determine the concentration of silica in respirable particulates within the building.

ATC collected four (4) samples for respirable dust using pre-weighed 37mm PVC filters connected to size-selective cyclones to remove the larger (non-respirable) particles prior to deposition on the filters. All four samples were collected indoors. The samples, plus one blank filter, were sent to PSC Analytical Services, Inc., an American Industrial Hygiene Association accredited laboratory in Reading, PA. Analysis was performed by x-ray diffraction according to OSHA Method 142. A copy of the analytical laboratory report is attached.

Tenzin Namgyal and Wagdi Abdelshahid, Industrial Hygienists of ATC’s New York City office, conducted the sampling consistent with generally accepted industrial hygiene practices. As with all such assessments, there were inherent limitations created by constraints of time, operational and work practice variability, variations in air contaminant concentrations and sampling and analytical accuracy.

CITY_2IMCl00_0 03020158

NYC-WTC_000208125