NYC-WTC_000196722

NYC 9/11 Public Portal Document

104 East 25th St. 10th Fl New York. New York 10010 www.atc-enviro com 212 353 8280 Fax 212 353 8306 ASSOCIATES INC.

September 13, 2002

Mr. Bernard P. Orlan Director, Environmental Health & Safety New York City Department of Education 28-11 Queens Plaza North Long Island City, NY 11101 -4008

Re: Air Sampling for Silica P. S. 126M ATC Project No. 15-19125-0343

Dear Mr. Orlan:

ATC Associates Inc. (ATC) is pleased to provide this report of the results of air monitoring for sihca-containmg dust conducted on August 29, 2002, at the referenced school. The New York City Department of Education (DOE) requested this monitoring prior to the resumption of classes to verify that acceptable indoor air quality is being maintained.

Scope of Work

ATC collected a total of five (5) samples (and one blank) 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 of the samples were collected indoors. The samples were sent to PSC Analytical Services, Inc., an American Industrial Hygiene Association accredited laboratory in Reading, PA. Analysis for silica was performed by x-ray diffraction according to OSHA Method 142. A copy of the analytical report is attached.

Wagdi Abdelshahid, Industrial Hygienist and Jimmy Choy, Environmental Technician of ATC’s New York City office, collected the samples consistent with generally accepted industnal hygiene practices. As with all such sampling, there were inherent limitations created by constraints of time, operational and work practice variability, variations in air contaminant concentrations and sampling and analytical accuracy. The results of the sampling represent conditions found on the dates the samples were collected.

Results

Samples were obtained in the following locations; 1^1 floor Main Lobby, 2nd floor hallway by Room 235, 3’’^ floor hallway by Room 317, 4th floor hallway by Room 435 and 4th floor hallway by Room 405.

The results of all of the samples were below the detection limit for silica (<5 micrograms per sample).

CITY_21MC100_003042516

NYC-WTC_000196722