NYC-WTC_000228415

NYC 9/11 Public Portal Document

104 East 25th St., 10th Floor New York. New York 10010 wwwatc-erviro.com 212.353.8280 Fax 212.353,8306 ASSOCIATES INC.

April 25, 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 March 28, 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 Ser\nces, 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 analytical report is attached.

Tenzin Namgyal and Wagdi Abdelshahid, Industrial Hygienists from ATC’s New York City office, conducted the sampling consistent with accepted industrial hygiene practices. The results represent the conditions on the day the samples were collected.

Results

Silica was found above the limits of detection in two samples. These were Sample #ATC-O328- 89M-S7 collected in Room 232 and Sample #ATC-0328-89M-S8 collected in the Auditorium. The Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) for silica-containing dust is based on the percent of quartz (SiO;) 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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