NYC-WTC_000197665

NYC 9/11 Public Portal Document

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

July 10, 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 Stuyvesant High School ATC Project No. 15-19125-0246

Dear Mr. Orlan:

ATC Associates, Inc. (ATC) is pleased to provide this report of air sampling for silica-containing dust conducted on April 3, 2002 at the referenced school. The New York City Board of Education (BOE) requested this sampling at the recommendation of H. A. Bader, a consultant to the parents’ association.

Scope of Work

ATC collected twelve (12) 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. One (1) outdoor sample and eleven (11) indoor samples were collected. The samples, plus a blank, 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.

Wagdi Abdelshahid Industrial Hygienists from ATC’s New York City office, conducted the sampling. The results represent conditions on the day the samples were collected.

The sampling locations were: L' Floor Main Lobby, Auditorium, Pool, 2'“* Floor Main Stair, 3"* floor Gym, 3"* floor Hallway center, 5* floor cafeteria, 5* floor Hallway center. Room #511 (South), Room # 701 (East), Room # 836 (North) and Outdoors East.

Results

Silica was found above the limit of detection in one of the samples. Sample # ATC-0403-STY- S4, collected in Auditorium, contained 0.0123 milligrams of silica per cubic meter of air (mg/m^). Silica was not detected above the analytical limit of detection in any of the remaining samples.

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.

CITY_21MC100_003046935

NYC-WTC_000197665