NYC-WTC_000214990

NYC 9/11 Public Portal Document

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

February 26, 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. 150M ATC Project No. 15-19125-0289

Dear Mr. Orlan:

ATC Associates, Inc. (ATC) is pleased to provide this letter report of air sampling for silica-containing dust conducted on February 11, 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 evaluation to assess the concentration of silica (total quartz) in the respirable particulates within the building.

Wagdi Abdelshahid, Industrial Hygienist of ATC’s New York City office, collected the samples.

ATC collected four (4) samples for respirable particulates 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 report is attached.

The assessment was performed consistent with generally accepted industrial hygiene assessment 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_21MC100_002853728

NYC-WTC_000214990