NYC-WTC_000208082

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.

August 5, 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 report of air sampling for silica-containing dust conducted on May 2, 9, 16, 23 and 30, 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

On each day, ATC collected ten (10) samples of 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 per day. Silica analysis was performed by x- ray diffraction according to OSHA Method 142. Copies of the analytical reports are 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 days the samples were collected.

Results

The Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) for silica-containing dust is based on the percent of quartz (SiO2) 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

The silica sample results of May 2, 9,16, and 23,2002, were below the limits of detection.

On May 30, 2002, silica was found above the limits of detection in only one location, This was Sample #ATC-0530-89M-S2, collected in 1“ Floor Hallway South.

CITY_21MC100_003019094

NYC-WTC_000208082