NYC-WTC_000202083

NYC 9/11 Public Portal Document

TC 104 East 25th St New York, New York 10010 www.atc-enviro.com 212.363.8280 Fax 212.353.8306 A S S 0 C I A T E S INC.

February 26, 2002

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

Re: Air Sampling for Silica P. S. 89M ATC Project No. 15-19125-0297

Dear Mr. Orlan:

' ATC Associates, Inc. (ATC) is pleased to provide this letter report of air sampling for silica- containing dust conducted on February 7, 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 collected ten (10) samples 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 samples were collected indoors. The samples were sent to PSC Analytical Services, Inc., an American Industrial Hygiene Association accredited laboratory in Reading, PA One blank filter was also submitted. Silica analysis was performed by x-ray diffraction according to " OSHA Method 142. A copy of the analjlical report is attached.

Tenzin Namgyal and Wagdi Abdelshahid, Industrial Hygienists of ATC’s New York City office, collected the samples.

Results

Silica was found above the limits of detection in one sample. This was Sample #S4-ATC-0207- 89M collected in the Gymnasium. The Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) for silica-containing dust is based on the percent of quartz (S1O2) found in the dust, the higher the percentage of quartz, the lower the PEL. The formula for calculating the PEL is found in 29 CFR 1910.1000, Table Z-3. The formula is:

lOmg/m^ %SiO2 + 2

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NYC-WTC_000202083